Immunology - Block 4 Tutoring

What does the "Wheal and Flare" reaction diagnose? What is the "Wheal and Flare" Reaction (swelling and redness)? What are the 3 steps to test a "Wheal and Flare" reaction?

"Wheal and Flare" reaction diagnoses positive for HSR Type I. Allergen-induced release of histamine by mast cells causes localized swelling (acute immediate response...the "wheal and flare" symptom) - will present immediately. 1. Subcutaneous Antigen - low dose 2. Mast Cell activation 3. Increased vascular permeability (via histamine from mast cell granule) leads to localized swelling R=ragweed pollen S=saline (negative control) H=histamine (positive control)

Reverse Transcription and Integration

**resting CD4 T cells are non-permissive hosts** 1. Virion binds to CD4 and co-receptor on T cell. - *CD4 & CCR5 or CXCR4* 2. Viral envelope fuses with cell membrane, and viral genomee enters cell - *Fusion at neutral pH* 3. Reverse transcriptase copies viral RNA genome into double-stranded cDNA - *RT: ssRNA to ds cDNA* 4. Viral cDNA enters nucleus and integrates into host DNA - *Integrate into chromosome* Only becomes problematic when these T-cells are activated during OTHER infections....then symptoms will present because the T-cells are replicating.

List 1 of the 4 forms of Immunosuppressive Therapy. What 2 ways can you prevent activation & proliferation of T cells? What are inhibitors of IL-2 production? What are inhibitors of both IL-2/IL-2R signal?

*1. Prevent activation and proliferation of T cells* *- Inhibitors of IL-2 production* *= Cyclosporin A, FK-506 (Tacrolimus)* - Inhibitors of both IL-2/IL-2R signal *= IL-2 antagonist mAbs (anti-CD25 Abs)* = *Rapamycin* (Sirolimus) inhibits IL-2R signaling 2. Remove actively dividing cells - Cytotoxic drugs (*azathioprine, cyclophosphamide - cures pemphigus vulgaris*) 3. Deplete peripheral T cells - Anti-CD3 mAb (OKT3), anti-CD4, anti-CD2 4. Inhibitors of inflammatory responses - Corticosteroids (*TALKED ABOUT THIS BEFORE*) - IL-1, IL-6, IL-8, TNF-, CAMs = Prostaglandins, Leukotrienes

Diagnostic testing algorithm for primary immunodeficiency disease What does the A50 test for? What does the CH50 test for?

*A*50 tests for *a*lternative pathway activity. *C*H50 test specifically tests for deficiencies in the *c*lassic pathway - measures ability of pt.'s serum to lyse ab-coated sheep RBC's

What are the 2 dermal HSV Type I Diseases? Which is transient and chronic?

*ATOPIC URTICARIA (HIVES)* - *TRANSIENT* *DERMATITIS (ECZEMA)* - *CHRONIC* Both are inflammatory skin responses; either transient (hives) or chronic (eczema) = Wheal and Flare reactions

Adaptive Immunodeficiencies - Humoral What is the cause of an adaptive immunodeficiency? What is the result of a Humoral Immunodeficiency? What are the 2 tests for humoral immunodeficiency?

*Adaptive Immunodeficiencies* - *Humoral* Immunodeficieny 1. First: An immunodeficiency caused by *defects in B-cell or T-cell activation and function.* 2. Second: If defects in B-cell development (not T-cell)... 3. Third: ...deficient Ab production... 4. Fourth: ... causing an *Inability to clear EXTRACELLULAR bacteria* Diagnostic testing algorithm for primary immunodeficiency disease - Humoral Immunodeficiency - *1. Lymphocyte phenotyping; immunoglobulin G subclasses Antigen stimulation* (tests which IgG's are present or absent???) --> 2. *Genetic/molecular testing* (see the gene that is causing the IgG deficiency???)

What % of the world population has autoreactive B cells? What are 2 ways of preventing formation or activation of B cells? HINT: Think location of B cell during development and circulation. What is the process for negative selection of B cells? What are the 2 general forms of peripheral tolerance of B cells? Who would autoreactive B cells be prominent for?

*All of us have autoreactive (IgM+; mature) B cells*. (Central Tolerance) Negative Selection of B Cell 1. Immature binds to self-antigen in bone marrow 2a. *Apoptosis* ...or... 2b. *Receptor Editing*: Modify V & J genes of light chain to express new antigen receptor. 2b -> 3. Mature B cell: no longer specific for self-antigen. Enters periphery. Peripheral Tolerance of B Cells 1a. Humoral/soluble self-antigen: *Anergy* ...or... 1b. Cell surface: *Apoptosis* The presence of autoreactive B cells *becomes obvious as one ages and loses T cell-mediated regulation*. - Aging patients, especially females, have low levels of many autoantibodies = Antinuclear antibodies (ANA) = Rheumatoid factor (RF) = Anti-thyroid antibodies etc.

What do all HSR's have in common? What are allergens composed (at least partly) of? Why? What happens during anaphylaxis? What is atopy? What is a commonly proposed hypothesis for atopy? What is hygeine hypothesis? What predisposes hygeine hypothesis? What is the mechanism for hygeine hypothesis?

*Antigens for ALL HSV's must be presented on MHC II (binds CD4 T cells)* Allergens: low molecular weight, *CONTAIN PEPTIDE FOR MHC II PRESENTATION* Anaphylaxis: *SHOCK*; severe hypotension (vasodilation via histamine) & bronchoconstriction (leukotrienes???) Atopy (atopic): *GENETIC TENDENCY FOR ALLERGIES* - present in childhood *Hygiene Hypothesis = Genetic susceptibility + Environment.* - Environment: More environmental exposure = less likely allergic response. = Predisposition: Excessive hygeines, antibiotics (curtail our immune response), & vaccination (prevents proper immune system response). = Mechanism: In sterile environment, immune response doesn't have microorganisms to fight so we have an allergic response to an innocuous substance; *Th2 BIAS (more Th2 than Th1; IgE dominated) STILL MAINTAINED* so exposure to an allergen winds up with allergies due to a Th2 response.

What is dangerous in regards to autoimmune diseases that involve IgG?

*Autoimmune diseases* that *involve IgG autoantibodies* can be *transferred to the fetus* via passive transfer - Transient effects (IgG can be catabolized)

Defect in what lymphocyte can result in SCID? Why are there never really "pure" T-cell deficiencies? When are SCID patients susceptible to infection? What is the most common opportunistic fungal pathogen in SCID?

*Defects in T-cell development* can result in *severe combined immunodeficiencies*. To perform a work-up on these individuals - need to do HIV testing and something testing T-cells (like DTH) - HIV will suppress immmune response - But if HIV Ab is [-] and DTH is [-]...and getting recurrent viral/ fungal/ and bacterial infections...then we know something must be going on... = Probably issue w/ T-cells Never "pure" T-cell deficiencies *as T cells are needed for optimal CD8 & B cell function* - Infections include intracellular organisms that require T cell/mac & CD8 interactions for control. = Listeria, MTB, Toxoplasma, fungi, protozoa and viruses. (DNTK) - *Susceptible* to infections *from birth* - Most common viral infections are cytomegalovirus, Epstein-Barr virus, varicella. = All these viruses can become LATENT (can't control) - Most common *opportunistic fungal pathogen is Pneumocystis jiroveci*. STARRED ON IMAGE: - ADA: Defective gene/protein (ADA; adenosine deaminase). - X-linked SCID: Defective gene/protein (IL2RG/common γ chain). - Complete DiGeorge Syndrome: Functional effect (defective thymus development and T-cell production). - Wiskott-Aldrich Syndrome (WAS): Clinical effect (Antibody deficiency, increased susceptibility to infections; thrombocytopenia with small platelets). = PET the WASP: "P"yogenic infection, "E"czema, "T"hrombocytopenia

What do defects in phagocytic cells allow? What are 3 syndromes that involve defects in phagocytic cells? EXTRA FOR NOW: ...what is the defective gene? ...what is the functional effect? ...what is the clinical effect?

*Defects in phagocytic cells permit widespread or chronic bacterial infections.* *Leukocyte Adhesions Deficiency (LAD)* - Can't adhere to site to kill. - Defective gene/protein: CD18 subunit of CR3, CR4, and LFA-1 adhesion molecules - Functional effect: Defective migration of monocytes and neutrophils to infected tissues. Defective uptake of opsonized pathogens. - Clinical effect: Widespread infection with encapsulated bacteria. *Chronic Granulomatous Disease (CGD)* - Doesn't have the agent to kill. - Defective gene/protein: Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase - Functional effect: Defective respiratory burst. Phagocytes unable to kill pathogens. - Clinical effect: Chronic bacterial and fungal infections. Granulomas. *Chediak-Higashi Syndrome (CHS)* - can't fuse IC vesicles to kill - Defective gene/protein: Lysosomal trafficking regulator protein - Functional effect: Defective fusion of endosomes and lysosomes. Defective phagocytosis. - Clinical effect: Recurrent and persistent bacterial infections. Granulomas. Damaging effects to many organs.

In Type IV HSR Mechanism Delayed Type Hypersensitivity occurs how long until after post-Ag exposure? What are the 2 general phases of HSR Type IV? What occurs during Sensitization phase? What occurs during Elicitation phase? ...cytokines released by memory cells? Describe their actions. ...what does macrophage do? What enzymes are secreted by macrophages? ...end result? Which diseases have a granulomatous formation?

*Delayed Cell Mediated*: - >48 hours post Ag exposure; cannot clear organism so chronic infection results. Sensitization Phase: Effector Th1 cells & memory cells formed = *Macrophage acts as an APC during sensitization* 1. Contact dermatitis: Due to hapten. - Otherwise I think it is just autoantigen presentation via sequestered antigen or molecular mimicry...as long as pathology is T cell mediated (as opposed to HSR II which is IgG pathogenic). 2. APC Uptake: Enters epidermis & binds self-protein forming *haptenated self protein* which ingested *by Langerhans cells (epidermis) & dendritic cells (dermis)*. 3. MHC II Processing: Haptenated protein is cleaved & presented on cell surface with *Class II MHC*. 4. APC-MHC II Presentation: Langerhans & dendritic cells migrate to lymph node, acting as APCs to activate *CD4+ & CD8+ T cells/CTL* (MHC I???); *cross-linking* to memory T cells. - Note nothing is mentioned about IgG formation which is critical in HSR II & III. Effector Phase: CD8+ CTL destroy target APC displaying peptide/Class I MHC, and macrophages destroy cells/tissues - Pathway 1: Contact Hypersensitivity??? (MHC I-CTL) 1. On *2nd exposure* to haptenated protein-Class I MHC, primed *CTL secretes perforin & granzymes*, cytotoxic for cells expressing the complex; targets APC's. - Pathway 2: Delayed Cell Mediated??? (MHC II- Th1) 1. On *2nd exposure* to haptenated protein-Class II MHC, Th1 cells releases cytokines = 1. & 2. INFγ & TNF-α: local tissue destruction = 3. & 4. GM-CSF & IL-3: more monocyte production BM, = 5. IL-8: chemokine = 6. MCAF: macrophage attractor 2. Cytokines recruit monocytes and induce their differentiation to macrophages to release cytokines, chemokines, and *lytic enzymes (hydrolases, oxidases) causing cell & tissue damage*. NOTE: Some type IV HSR will have Abs but they are not causing the damage -> simply damaged cells release their contents which then began a 2nd immune rxn.

What is the diagnostic testing for LAD? For LAD I... ...what is the problem in LAD I? ...what is the defect? ...what is the age of onset? ...what are the 3 (of the 4) signs & symptoms? ...what are the 2 Diagnostic tests? What is wrong in LAD II?

*Diagnosis: High counts (repeat counts) of CD11/18 assay.* LAD I Deficiency: *CD18 deficiency (integrin beta 2 chain) AKA LFA-1 (CD11a/CD18)* for *tight binding* phase (occurs after rolling and before diapedesis). - Defect: *disorder of neutrophil function - NO diapedesis* - Age of Onset: *1-2 months* of age (early onset). - Mode of Inheritance: A.R. - S/s: 1. *Severe periodontal disease (i.e. gingivitis)* 2. *Delayed wound healing - absence of pus* 3. Leukocytosis: *Elevated white blood count* 4. Umbilical Cord - Delayed separation at birth, postnatal redness and swelling (omphalitis) Dx Tests: 1. *Rebuck Skin Window* - skin abraded and cover slip applied to visualize adhered leukocytes 2. Flow Cytometry/*FACS*: *Cell should end up on cover slip - if no cells...LAD+* Treatment: BMT (bone marrow transplant) LAD II: No *CD15 (Sialyl Lewis)* for *rolling* phase FLOW CYTOMETRIC ANALYSIS OF ADHESION MOLECULES ON NEUTROPHILS - LAD II: No CD15 = Sialyl LewisX = defective rolling - LAD I: No CD18 = LFA-1 (Integrin Beta 2 Chain) = tight binding deficiency

Wegener's Granulomatosis (Granulomatosis with Polyangiitis) What is the HSR type? What is the autoantigen & autoantibody? What is the mechanism? What is the clinical manifestation? ...what is the hallmark clinical feature? What are the 3 factors used to diagnose?

*HSR Type III* Predominance: slightly male, onset 45-60yrs, caucasian Initiating Antigen: *Proteinase 3 (PR3)* the target antigen of anti-neutrophil cytoplasmic antibodies *(c-ANCA)* - W (for Wegeners) turned over gives a 3 (PR3). Cut 3 in half to give a c (C-ANCA). Mechanism: - Normal: intracellular PR3 expression on PMN induced by inflammatory cytokines; PMN bind to endothelial cells and degranulate following binding. This results in local endothelial cell lysis and necrotizing vasculitis. - Pathologic: *Autoantibodies (c-ANCA) bind to neutrophils (PR3) and induce a respiratory burst* (degranulation results). Clinical Manifestation: *Inflammation & damage of blood vessels* (esp. *pulmonary vasculitis, URT/LRT, kidney*) Clinical Features: - Airway Symptoms: rhinitis, cough, chest pain, sinusitis, congestion - Kidney disease, due to glomerulonephritis - *Saddle nose*, due to cartilage damage in bridge *Diagnosis*: - Detection of serum *anti-PR3 ANCA (aka cANCA)* - Chest X-ray: - *Cavitary lung lesions*, *lung nodules* - Upper respiratory tract granulomas Treatment: - Both cyclophosphamide + corticosteroids

Pernicious Anemia ...what is the HSR type? ...what is the mechanism? How is Pernicious Anemia diagnosed?

*HSR Type IV = initiates* *Often considered an HSR Type II* Mechanism & Result 1. Type IV effect: T Cell destruction of parietal cells (responsible for secreting IF) (Why destroy???) 2. *H+/K+-ATPase* autoantigen released into circulation and presented by APC in LN to lymphocytes. 3. Type II effect: eAutoantibodies made against gastric parietal cells (*H+/K+-ATPase*) as well as intrinsic factor (IF). - Previously lumenal *H+/K+-ATPase* and IC IF were inaccessible prior to T cell destruction of parietal cell, which released them into circulation. - SECONDARY TO T CELL DESTRUCTION OF PARIETAL CELLS 4. Result: Due to damaged/neutralized IF, vitamin B12 deficiency (uptake blocked by IgA [because IgA is mucosal whereas IgG is circulatory???]) Diagnosis: Detection of *anti-parietal cell & anti-IF antibodies useful for diagnosis (not pathogenic!)* - Evidence for *Type IV HSR* response *against H+/K+-ATPase leading to parietal cell destruction and release of autoantigens*

Multiple Sclerosis Which HSR type? In pathogenesis of MS... ...what generally happens? Be specific on all cells involved. ...what is the pathogenic process of MS? Include autoantigens involved. What is the result of pathogenesis? What is a symptom of MS a patient presents? Why?

*HSR Type IV* MS is a chronic disease of the central nervous system (CNS) Pathogenesis of MS: *CD4 Th1 cells, Th17 cells and B cells* infiltrate CNS. Forms ectopic lymphoid tissue 0. Brain is immunopriviledged site = "Unknown trigger" for permeability & inflammation??? "Reencounter"??? 1. Autoreactive *T-cells target and attack* myelin proteins. - Myelin basic protein (*MBP*) - Myelin oligodendrocyte glycoprotein (*MOG*) 2. *Demyelination is mediated by CNS-resident macrophages (microglial cells)* following their activation by Th1 cells. (What about Th17 cells & B cells???) Result of Pathogenesis: - *Chronic inflammation* leads to *destruction of myelin sheath* (seen as plaques or scleroses) of nerve fibers in *brain & spinal cord* (white matter) due to *autoreactive T cells* = Plaques contain lymphocytes, plasma cells, and macrophages Paralysis: Disruption of neural transmissions as *demyelinated axons cannot effectively transmit APs*. Common cause of chronic neurological disability in young adults.

What does IPEX stand for? Be specific on targets affected. What is the cause of IPEX? What is the treatment of IPEX?

*I*mmune dysregulation *P*olyendocrinopathy: diseases affecting multiple *endocrine glands* *E*nteropathy: disorder of the *intestines*, as well as *skin* *X-linked syndrome* Cause: Inactivating mutation or deletion of Foxp3 so *Tregs absent or non-functional* → immune dysregulation (loss of peripheral tolerance) *TREATMENT*: Hematopoietic stem cell transplantation within the first year of life. EXTRA: Multiple clinical phenotypes of varying severity

What are 2 other factors predisposing to autoimmunity? Explain each.

*Immune senescence* (Aging and Autoimmunity): Associated with *erosion of self-tolerance* - The frequency of autoantibodies increases with aging, attributed to altered T cell and B cell function in the elderly - Example - *Thymic Involution*: Shrinks w/ age = decrease in self-tolerance = mTEC's (neg-selection AKA Self-Tolerance) are replaced w/ fat cells EXTRA: If its an autoimmune or endocrine disorder, it is MUCH MORE COMMON IN FEMALES (there are a few exceptions)

A.R. SCID - many different causes List all 4 of them. Since the title explains what is deficient, what were these supposed to do? What would lab tests show; which would be T-/+ and B-/+?

*JAK3 deficiency: JAK-STAT signaling pathways* •*T-, B+ SCID (CD3+ missing)* •mutation in the JAK3 gene; no signal tranduction through the IL-2R or the common γ chain •*Phenotype similar to X-SCID* CD45 (LCA) deficiency: *Expressed on all WBCs* •*T-, B+ SCID* •mutation in the Protein Tyrosine Phosphatase Receptor Type C (PTPRC) gene locus 1q31-q32. IL-7Rα deficiency: *Signal for V-D-J joining* •*T-, B+ SCID* •Mutation in IL-7Ralpha gene locus 5p13 CD3δ or CD3ε deficiency: *Pre-TCR, TCR signaling pathway* •*T-, B+ SCID* •Mutation in CD3δ or CD3ε gene locus 11q23

Which MHC gene/component is critical in determining MHC mismatch or graft survival? ...why? What is the 2nd? What is the 3rd?

*Mismatch in HLA-DR (an MHC-II) = strongest rejection* - *DR is most polymorphic* - *Match DR 1st, then A, then B*: When matching tissues for transplantation, it is imperative that the physician match DR 1st to avoid rejection. If matched, greatest chance of preventing rejection; want to match that which is most likely to be different and cause problems *HLA-A is the 2nd most polymorphic* *HLA-B is the 3rd most polymorphic*

What are the 2 mediators of Molecular Mimicry? What is the process of T-Cell Mediated Molecular Mimicry? What is the process (via example of Rheumatic Fever) of Antibody Mediated Molecular Mimicry?

*Molecular Mimicry can be mediated by T cells or Abs* T cell Mediated - Self-Peptide Mimic: Combination of self-peptide & foreign peptide. (*This is an accident*) 1. APC Presentation: The same MHC molecule presents both a pathogen peptide and a self-peptide that mimics it. 2. Naive T Cell Activation: Naive T cell is activated by the pathogen peptide presented by the particular MHC molecule. 3. Macrophage Activation: Effector Th1 cell responds to the self-peptide mimic and activates the macrophage, causing inflammation. Antibody Mediated - Rheumatic fever: anti-*strep*tococcal antibodies *cross-react* with heart tissue (because of M protein). 1. Streptococcal cell wall stimulates antibody response 2. Some antibodies cross-react with heart tissue, causing rheumatic fever.

Genes and Autoimmunity: Monogenic Autoimmune Diseases ...what influences monogeneic autoimmune diseases? ...how is this proven in monozygotic twins?

*Monogenic is the exception to the rule!!! —> generally multifactorial* *Concordance rates for monozygotic twins are not 100%* due to epigenetic and/or environmental factors in autoimmune diseases (multifactorial).

Why are all HSR IV antibodies diagnostic?

*Note that Type IV HSR Ab's are all diagnostic* - Cause: *PATHOGENESIS OCCURS PRIMARILY BY BY T CELLS (commonly through macrophages or CTLs, etc.)*. = Type IV over Type II: *Ab's in Type IV form (and damage???) secondary (after) to T cell (primary; first) damage because damage leads to exposure of sequestered Ag's!* Pernicious anemia is HSR Type IV (T-cell mediated): because T cells first destroy the parietal cells then the ATPase pump gets exposed to autoantibodies (HSR Type II).

What is significant about maternal IgG? What significance does maternal IgG have for an immunodeficient fetus? What are the features (common presentation) of patients with B-cell deficiencies? ...Why?

*Passively transferred maternal IgG* - *Healthy infant (despite immunodeficient) until maternal antibodies wane* as maternal antibodies will be present for about first 6 months. Delayed onset of the disease after 6 months. *Features of Patients with B-Cell Deficiencies* - Common Presentation: *Recurrent sinopulmonary infections and septicemias*. = From extracellular pyogenic bacteria *with polysaccharide capsules because of decreased opsonization* (low IgG/IgM and thereby complement; ...C3b in alternative too???) *so little if any phagocytosis* (...or MAC lysis???). - Predominating organisms in the infectious spectrum are = Streptococci = Staphylococci = Haemophilus spp. - Susceptible to invasive disease with enteroviruses entering through the gut (because lack of IgA production???).

Xenotransplantation ...what species is the most likely donor? ...for what anatomical component? ...what causes hyperacute rejection? ...what causes delayed rejection?

*Pigs are the most probable donor (Heart Valves)* Pre-formed antibodies from sensitization???; Humans have *natural (heterophilic - antibodies induced by ext ant.) Abs* to donor Ags resulting in *hyperacute rejections* *Delayed rejection is primarily mediated by NK cells and macrophages* T cells do not mediate profound rejection - Low crossreactivity of the human TCR for the porcine MHC = Our TCR's don't bind well to other species MHC

What is a syndrome of HSR Type III? What is the autoantigen and resulting consequence?

*Rheumatoid arthritis has a Rheumatoid factor that's an IgM auto antibody against IgG (IgM anti-IgG), forming the immune complexes.* - Rheumatoid Arteritis is both Type IV and III as joint damage is Type IV mediated. = Autoantigen: Unknown synovial joint antigen, causing joint inflammation and destruction. = Consequence: Arthritis.

What are 6 (of 10) factors that raise suspicion of an Immunodeficiency in an Infant/Child? What is significant about the resolution of an infection? What are 2 examples of resistant candidiasis?

*Suspicion of an immunodeficiency in infant/child* 1. *Recurrent* and *serious* infections raises 2. *Family hx of an immunodeficiency* 3. *IV antibiotics and/or hospitalization* are needed to clear infections 4. *2 or more* serious sinus infections or *pneumonias within a year* 5. Two or more episodes of sepsis or meningitis (infectious spread) - Can't hold infection at bay / *lack of complete resolution* 6. Recurrent or *resistant candidiasis (fungal infection/ yeast) - its normal flora so it usually does not cause us problems because our immune response can usually control/contain its growth* - *Severe diaper rash or thrush* 7. Infection with an *opportunistic organism*. Kind of related to candidiasis. - *NOT normally a problem..means our defenses are lowered* 8. Recurrent tissue or organ abscesses 9. Complications from a live vaccine i.e. Polio vaccine - not weakened enough - overpowers already weakened immune system. 10. Chronic diarrhea, nonhealing wounds, extensive skin lesions

Pemphigus vulgaris ...which HSR type? ...what is the initiating antigen and what is its significance? ...what is the mechanism? ...what results from the mechanism and what are the clinical features? What is the primary population that suffers from Pemphigus Vulgaris? How would you diagnose Pemphigus Vulgaris?

*Type II HSR* *Initiating Antigen: Desmoglein 3* - component of *desmosomes* (adhesion molecule) that form junctions between keratinocytes. *Mechanism*: *Produce autoantibodies* (usually IgG) *against desomogleins* (EC5 to EC1???), for MAC lysis or C3d-CR1 phagocytosis. Clinical Features: *Loss of cell-to-cell adhesion (acantholysis)*, results in *blistering skin* (skin disorder). Blister may cause loss of fluids, proteins, and electrolytes. *High frequency in Ashkenazi Jewish populations* *Diagnosis*: Immunohistological demonstration of anti-desmoglein; detection of acantholysis Treatment: Aggressive immunosuppressive therapy: high-dose steroids, cyclophosphamide.

Autoimmune Hemolytic Anemia ...what type of HSR is this disease? ...what generally happens? ...how are these cell destroyed? ...what causes production of anti-RBC Abs? What are 3 other forms of hemolytic anemia? What is the initiating antigen for hemolytic anemia involving... ...molecular mimicry? ...alloantigen incompatibility? ...drug-induced? What are 3 clinical features of (drug-induced) hemolytic anemia? How would you diagnose (drug induced) hemolytic anemia? Be specific.

*Type II HSR* Mechanism: Anti-RBC autoantibodies produced & bind to RBC's for lysis. 1. Phagocytosis: C3b-CR1 opsonization or FcR-dependent uptake - Particularly occurs in spleen. 2. Complement-mediated lysis (MAC) (ADCC or just for IC viruses even if complement formation???) *Molecular Mimicry* (an accident) causes production of anti-RBC Abs (...so infection???) - When we're born we make IgM to our normal flora (commensals) antigens that looks a lot like A and B blood group antigens Other forms of hemolytic anemia due to (discussed last session) 1. HDNB - HSR Type II 2. *Alloantigen incompatibility (e.g. anti-RhD)* - HSR Type II 3. *Drug-induced (alters RBC glycoprotein structure) - Penicillin* - HSR Type I??? Initiating Antigen: frequently unknown 1. Molecular mimicry - microbial antigen & RBC antigen 2. Alloantigen incompatibility - i.e. Rh factor/D antigen 3. Drug-induced: Modified RBC becomes "foreign" - penicillin and other drugs coat RBCs/platelets Drug-induced Hemolytic Anemia (RBC's attacked) & Drug-induced Thrombocytopenia (platelets attacked) 1. Hapten-RBC: Penicillin or other drugs bind to surface glycoproteins of RBCs or platelets. 2. Ab Production: Modified RBCs/platelets induce antibody production 3. Hemolysis: Antibodies are specific for drug-modified membrane proteins RBC/platelet lysis or opsonization Clinical Features: *Anemia, thrombocytopenia, hepatosplenomegaly* - either Cold agglutinins (IgM) or Warm agglutinins (IgG) Diagnosis: Detect autoantibodies using direct Coombs test - *Spherocytes* in blood smear

Ankylosing Spondylitis (AS) What is the HSR Type? Who is prone to AS? Be specific. What is the genetic predisposition? What is the clinical manifestation?

*Type IV HSR* *90% male*; onset 15-30 years - Very strong association with *HLA-B27* (95% cases) *Chronic spinal inflammation* (spondylitis) can lead to new bone growth and fusion of vertebrae (ankylosis; bent)

Addison's Disease Which HSR Type? What is the mechanism?

*Type IV HSR* Mechanism - Autoimmune *destruction of the adrenal cortex* via autoreactive CD8 T cells and by Th1 cells (IFNγ-dependent macrophage activation), releasing autoantigen 21-hydroxylase. = Deficient production of cortisol and aldosterone = Associated with autoAbs against *21-hydroxylase* - Not pathogenic

Immunopathogenesis of Hashimoto's Thyroiditis Which HSR Type? What is the cause? Be specific. What does infiltration of lymphocytes result in gross anatomy, as well as continued autoimmunosuppression? How would you diagnose Hashimoto's Thyroiditis?

*Type IV HSR* - *T-cells are the pathogenic mechanism*. Chronic thyroiditis Cause - *DTH (Th1) in Thyroid*: *Innapropriate expression of MHC II* (HLA-DR5 & HLA-DR3) *on thyroid cells* (T cells???) *allows recognition by CD4+ T cells* (Th1). - *Leads to CD8 (CTL's) activation which destroy thyroid cells* for release of autoantigens (*TPO & thyroglobulin*). What about Th1 activation of Mφ's (lytic enzymes)??? Infiltration of lymphocytes (*CD4 & CD8 T cells, B cells*) leads to Goiter (ectopic thyroid tissue)... =...as well as attack mediated by (non-pathogenic???) autoantibodies *anti-thyroglobulin (Tg-Ab) & anti-thyroid peroxidase (TPO)*, causing hypothyroidism. *Diagnosis*: Thyroid histology (well-developed germinal centers) - *Production of non-pathogenic autoantibodies anti-thyroglobulin (Tg-Ab) & anti-thyroid peroxidase (TPO)* = *Autoantibodies are epiphenomena not the pathogenic mechanism*. EXTRA: Usually middle-aged women; 50:1. Treated with synthetic thyroid hormone daily

HIV is a retrovirus that *infects CD4 T cells* and macrophages. What does it exactly bind to on CD4 cells to infect? Is it a lytic or latent virus?

*gp120 & gp41*: - *bind to CD4, Co-receptor on T- Cells* - CCR5 or CXCR4, Integrase associated with *latency* Enveloped, diploid, positive sense single stranded RNA virus, with reverse transcriptase, integrase and protease gp120 binds host cell receptor CD4

What are 2 experimental therapies for immunosuppresive therapy?

1. *Block co-stimulation (CD28)* - Co-stimulatory molecule antagonist - CTLA4-Ig (e.g. *Belatacept*) = Inhibit delivery of signal-2 (CD28-B7) stops T-cell activation 2. *Block CD40L* (no B cell activation/differentiation/production of Ab's???) - *Anti-CD40L Ab*

Which HSR respons do FOOD ALLERGIES fall under? Be specific on timing. Other than common food allergens, which food allergen can be confused as a Type I HSR, but is actually Type 4 HSR? What is the associated disease? Where do initial symptoms occur? What can food allergens in late phase cause? Why?

1. *Food allergies, an IgE-mediated immediate HSR most frequently*. 2. Most common allergens: nuts (especially peanuts), shellfish, eggs, cow's milk and soy proteins, (*gluten not Type I HSR - it's a Type IV - Celiac Disease*). 3. First, symptoms may be *local (GI tract*: lip swelling, tingling and itching in the throat, nausea and vomiting, abdominal cramps, diarrhea). Caused by smooth muscle contraction (lipid mediators; kinin cascade). 4. Food allergens can cause *generalized systemic reactions*, including dermal (itching and rash), diffuse swelling (angioedema), upper and lower respiratory tract symptoms (runny nose--aka rhinorrhea, dypsnea and wheezing, and anaphylactic shock) - *once absorbed into blood*.

List 10 important drugs. Give their functions.

1. *Omalizumab* - mAb to Fc region (FcεRI) of IgE blocks arming of mast cells for hypersensitivity 2. *Rhogam* - Treat Erythroblastosis fetalis, IgG anti-Rh, sends negative signal via FcγRIIB preventing B-cell activation. PREVENTION NOT TREATMENT. 3. *Cyclophosphamide* - immunosuppressive steroid, treat pemphigus vulgaris 4. Rituximab (*Rituxan*) - anti-CD20 Ab to deplete circulating B-cells for rheumatoid arthritis treatment 5. *Infliximab & Adalimumab* - Anti-TNFα, treat RA 6. *Cyclosporine A* (Sandimmune®)- inhibits T cell proliferation by blocking IL-2 production 7. *FK506* (Tacrolimus®) - inhibits T cell proliferation by blocking IL-2 production 8. *Rapamycin* (Sirolimus®) - inhibits lymphocyte proliferation by blocking response to IL-2 9. *Azathioprine* - inhibits cell proliferation (purine analog) 10. *Plasmapheresis* (decrease/remove circulating antibodies) - Think type II & III HSRs 11. Corticosteroids - anti-inflammatory e.g. prednisone, hydrocortisone, dexamethasone 12. Cyclophosphamide - kills proliferating cells (alkylating agent) 13. Etanercept - TNFR-Ig, block TNF in treatment for RA

What is the sensitization phase of HSR Type III? What is the effector-elicitation phase of HSR Type III? During effector-elicitation phase of HSR Type III... ...what do immune complexes do, and what is the result? ...what do basophils do? ...what do neutrophils do? Be specific. (HINT: 2 terms)

1. *Sensitization Phase*: Makes IgG & IgM specific for soluble antigen that form immune complexes - Normally, RBCs transport IC's to spleen or liver for disposal = C3b bound to IC, then binds CR1 on RBC's. 2. *Effector-Elicitation Phase*: Problem phase in which more IC's produced than removed from circulation (*equal antigen and antibody*). 2a. Immune complexes *deposit* in capillary walls 2b. Complement activation: *C5a (neutrophil recruitment + mast cells) and C3b (opsonization)*. 2c. Basophils bind C5a for histamine release, causing *↑permeability for further neutrophil infiltration*. 2d. *Frustrated Phagocytosis*: Neutropils recruited by C5a cannot phagocytose IC (Fcγ-IgG or C3b-CR1 needed), instead releases toxic agents into environment. - *Bystander Damage*: Tissue damage by neutrophil's toxic agents = Frustrated neutrophils secrete inflammatory mediators that damage endothelium -> intrinsic coagulation -> bradykinin -> ↑vascular permeability.

SCID - Severe Combined Immunodeficiencies What is the immune defect and susceptibility of... ...ADA deficiency? ...PNP deficiency? ...X-linked SCID γc chain Deficiency? ...Autosomal SCID DNA repair?

1. ADA Deficiency - Immune Defect: No T or B cells - Susceptibility: General 2. PNP Deficiency: - Immune Defect: No T or B cells - Susceptibility: General 3. X-linked SCID γc chain Deficiency: - Immune Defect: No T cells - Susceptibility: General 4. Autosomal SCID DNA repair: - Immune Defect: No T or B cells - Susceptibility: General

What are the affected genes, immune defect, and susceptibility for... 1. Asplenia 2. APECED 3. IPEX

1. Asplenia - Affected Genes: Unknown. - Immune defect: No spleen. - Susceptibility: Encapsulated extracellular bacteria. 2. APECED: autoimmue polyendocrinopathy-candidiasis-ectodermal dystrophy - Affected Genes: AIRE - Immune defect: Reduced T cell tolerance to self-antigens - Susceptibility: Autoimmune diseases 3. IPEX: immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome - Affected Genes: Foxp3 - Immune defect: Lack of Treg cells and peripheral tolerance - Susceptibility: Autoimmune diseases

What are the 3 targets of allograft (same species) and xenograft (different species) the result in rejection? What are the 2 forms of MHC I & II allorecognition? What is an example of minor histocompatibility antigens?

1. Blood group (ABO) antigens - Blood transfusions (discussed last session) 2. MHC I & MHC II (cross-presentation); presenting alloantigens on transplanted donor organ to the recipient's T cells - *Direct (Donor presents)*: Donor's own APCs migrate to lymph node or spleen and (MHC???) is recognized by alloreactive recipient T cells. - *Indirect (Recipient presents)*: Recipient's APC takes up and processes proteins derived from the graft, and is recognized by recipient T cell receptor. 3. Minor Histocompatibility antigens - *Polymorphic proteins*

What are the steps in Arthus Reaction?

1. IC formation: On 2nd exposure, preformed IgG will bind to *LOCALLY INJECTED ANTIGENS*. - Can occur at *SITE OF TETANUS BOOSTER* 2. C5a: IC activates complement, releasing C5a to sensitize mast cells 3. Mast Cell Degranulation: in response to FcyR-IgG (IgG of IC) (so not just IgE??? Is C5a just for chemotaxis and not binding??? What about basophils???). 4. Local Inflammation: Degranulation recruits neutrophils to promote inflammation (blood vessel occlusion [???], fluid & protein release, phagocytosis [???]). - Lasts for ~4 - 12 hours Note: When mast cells bind both IgG & IgE, the reaction is inhibitory.

Miscellaneous Immunodeficiency Phenotypes List all 4 miscellaneous Immunodeficiency Phenotypes. What is the cause/deficiency of IFN-γR1 deficiency and what is the defect of this deficiency? What is the problem(s) of XLP? What is atypical T-cells are developed in XLP? What is a genetic defect in XLP and why is this gene important?

1. IFN-γR1 deficiency (Supposed to bind to IFN-γ for macrophage activation???). - Normal pathways for host defense against *intracellular bacteria* are pinpointed by genetic deficiencies of IFN-γ and IL-12 and their receptors. - Requires 2 recessive IFN-γR1 alleles - *TH1 impacted = decrease macrophage activity* 2. X-linked LymphoProliferative syndrome (XLP) - *Deficiency: SH2D1A (SLAM associated)* = *SLAM & SAP enhances T-cell activation and cytotoxicity* - *Defect: No T-cell control of EBV infection (can't kill infected B-cells)* = Associated with *fatal infection by Epstein-Barr virus* & with *development of lymphomas*. - Abnormalities in secretory cytotoxic pathway of lymphocytes = uncontrolled lymphoproliferation & inflammatory responses to viral infections. - *Develop atypical T-cells known as Downey cells* 3. Wiskott-Aldrich Syndrome (WAS) - Inability of T cells to reorganize their actin cytoskeleton 4. Ataxia-Telangiectasia (AT) - A defect in double-stranded DNArepair.

Secondary (Acquired) Immunodeficiency - B cell malignancy (myeloma) What are the 2 types and what is the Ig type?

1. Multiple Myeloma - *IgG* 2. Waldenstrom's Macroglobulinemia - *IgM* Trick to remembering: 2 M's cancel out in Multiple Myeloma so IgG myeloma 1 M in Waldenstrom's Macroglobulinemia so IgM myeloma

Hypersensitivity Type I: Diseases - Penicillin/Drug Allergies What is the process in which Penicillin can cause HSR Type I? What is the end result of HSR Type I inolving penicillin?

1. Penicillin-RBC complex - *Penicillin* is a hapten. 2. APC (Macrophage) phagocytose & process Pencillin-RBC complex for MHC II presentation to naive CD4+ T cells. - As opposed to HSR Type II which is mediated by IgG, and Th1. 3. Naïve T cell differentiate to Th2 cells (via IL-4) 4. B cells activation/differentiation for IgE production, specific for penicillin hapten. - Penicillin-RBC complex (bc RBC is also an APC) and Th2 cells (via IL-4 & IL-13???). 5. IgE binds to mast cells 6. RBC-penicillin complex crosslinks IgE, mast cells degranulate. - Histamine for increased vascular permeability 7. Mediators (Eg histamine) circulating in blood can trigger *anaphylaxis*. *Penicillin(Hapten)-RBC* complex cause Macrophage phagocytosis & MHC II presentation, activating Th2 cells, activating B cells for IgE production, causing *Mast cell degranulation -> Histamine -> Increased vascular permeability -> Anaphylactic shock*

For Type III HSRs, the antigen(s) & clinical manifestation(s) in... ...serum sickness? ...Arthus reaction? ...Systemic Lupus Erythematosus? ...Post-Streptococcal Glomerulonephritis?

1. Serum Sickness - Antigen: Various proteins - Clinical Manifestations: Arthritis, vasculitis, nephritis 2. Arthus Reaction - Antigen: Injected (cutaneous) proteins & Fungal antigens - Clinical Manifestations: Local inflammation & Farmer's lung respectively. Systemic Lupus Erythematosus - Antigen: Nucleoproteins, dsDNA - Clinical Manifestations: Nephritis, arthritis, vasculitis, rash 3. Post-Streptococcal Glomerulonephritis - Antigen: Streptococcal antigens - Clinical Manifestations: Nephritis. *Lumpy Bumpy Pattern.*

What are the 3 steps of immunoelectrophoresis of serum from normal or XLA patient - separation by charge? What would be the resulting pattern of a person with XLA?

1. Serum samples: are added to immunoelectrophoresis plate - Serum of person with recurrent infection, and serum from normal individual on other side. 2. Serum components separated: by electrophoresis - Movement by attraction to correct charge (globulins move to the +, or the -). - Separating by CHARGE (not the same as ouchterlony) 3. Anti-human Ab complexes with Human Ag's: Rabbit (*anti-human serum*; *anti-human Ab*): added to the central trough and diffuses into the plate, forming precipitin lines. *RESULTING PATTERN*: All Ig's of XLA are missing, so there will not be a precipitation line. In contrast, a normal person will have precipitation, so there will be a line.

Entry of HIV into cells

1. gp120 binds to CD4 on T cells and macrophages/monocytes 2. gp120 changes conformation (exposes GP41) - and binds CCR5 or CXCR4 (that's why a mutation in this gives immunity because no fusion occurs) 3. gp41 has pH independent fusion activity - fusion w/ host membrane at neutral pH ...dumps genes into cytoplasm..syncytia upon exit

Replication Cycle of HIV What are the 7 general steps?

1.-2.) Entry of HIV into cells 3.) Reverse transcription 4.) Integration 5.) Transcription 6.) Translation 7.) Assembly and budding

What would suggest an immunodeficient disease? What is a primary immunodeficiency disease? What is a secondary immunodeficiency disease?

A history of *repeated infections* suggests a diagnosis of immunodeficiency. Primary immunodeficiency: diseases are caused by *inherited gene defects*. Hematopoietic stem cell transplantation or gene therapy can be useful to correct genetic defects. - Cause: Mutations, polymorphysms, polygenic disorders. Secondary immunodeficiencies: are *acquired* and are major predisposing causes of infection and death.

ADA - Adenosine Deaminase Deficiency ...what is the cause? ...what is the defect of deficiency? Be specific. ...what do labs show? PNP - Purine Nucleoside Phosphorylase Deficiency ...what is the cause/deficiency? ...what is the defect of PNP? Be specific. ...what is the sign? ...What do labs show? ...what pathway is corrupted?

ADA - Adenosine Deaminase Deficiency - Cause: *Adenosine deaminase gene* so no Adenosine Deaminase - Defect of Deficiency: *Accumulation of adenosine, deoxyadenosine, and dATP is toxic for lymphocytes.* - Inheritance: AR mutation - LABS: *T -, B -, NK -; ALL NEGATIVE* - toxicity (high adenosine) killed them all. - TX: PEG-ADA, or haploidentical BMT PNP - Purine Nucleoside Phosphorylase Deficiency - Deficiency: *Purine Nucleoside Phosphorylase gene* - Defect: *Accumulation dGTP* = *Toxic for T-cells moreso than B-cells; neither present* - MoI: RARE - S/s: *Ataxia* (loss of muscle coordination/gait) *w/ deficient cellular immunity* - LABS: = *Decreased # of T-cells* = *Lymphopenia (as usual)* = *T-, B-, NK-, all negative* NOT AS SEVERE AS ADA *Purine salvage pathway messed up*

What is AIRE...for? ...induces? ...in what cell type? ...component of (be specific)? What is the cause of APECED Syndrome? ...cellular effect of the cause of APECED?

AIRE (AutoImmune REgulator) - Transcriptional activator for *ectopic* expression of *peripheral tissue-specific antigens* in *medullary epithelial cells (MEC)* of the thymus. - This is a significant component for a functional *central* T cell tolerance, specifically *negative selection*. APCED (Autoimmune PolyEndocrinopathy Candidiasis Ectodermal Dystrophy) aka Autoimmune Polyendocrinopathy Syndrome (APS) - Cause: Inactivating mutations in AIRE. This *blocks central tolerance and result in autoimmune attack on many tissues*. - Result: T cell-driven autoimmune disorders, as there is no... 1. ...no elimination of self-reactive T cells 2. ...no elimination of defective Tregs (defective Tregs are incapable of stopping/immunosuppressing self-reactive T cells???)

Mutant Proteins in Primary Immunodeficiency Diseases What are the 4 (of 5) mutant proteins in Primary Immunodeficiency of T cells? What are the 3 mutant proteins in Primary Immunodeficiency of B cells?

Activated CD4+ T Cells (Panel A) Only image here - *CD40L* - *IL-2Rγ, Jak3* - *WASP* - *ATM* - SH2D1A B Cells (Panel B) - *Btk* - *BLS I* - *BLS II*

Activation-Induced Cytidine Deaminase (AID) Deficiency ...what is the cause and deficiency? ...what are the 3 defect of deficiency? Why are 1 of these defects important. Selective IgA Deficiency ...what is the defect? ...what symptoms result from this defect? ...why? ...what are 2 important unique things about Selective IgA Deficiency?

Activation-Induced Cytidine Deaminase (AID) Deficiency - Causes *Autosomal Recessive* form of Hyper-IgM Syndrome (*HIGM2*); *DIFFERENT way to get Hyper-IgM* (no CD40L???) - Deficiency: *AID* - Defect of Deficiency: 1.) Lack of Somatic Hypermutation in Ig's - Main role of AID 2.) NO Ig class switch 3.) Lymph node hyperplasia due to *giant G.C.'s* (...due to B cell activation whereas *no G.C. in XHIGM*; differentiate). - Inheritance: A.R. - S/s: same as XHIGM (because only XHIGM) - Dx: Confirm via presence of Hyperplastic LN's (due to *giant G.C.'s*) - Unique: T-cells CAN help B-cells; will see proliferation! Selective IgA Deficiency - Cause: UNKOWN - Defect of Deficiency: *Deficiency or absence of IgA and sIgA* since *B-cells won't mature into IgA producing plasma cells* - *S/s*: *Weakened mucosal defenses*; *GI, Resp, Urogenital infections*. - Unique: Most common primary (inherited) immunodeficiency. = Can be acquired (secondary too) in measles or viral infection. = LARGE variability in presentation: *Some asymptomatic, some symptomatic* = *Anaphylaxis: If blood transfused contains IgA as they have never seen IgA*. - Associated w/ asthma/ food allergies/ Rheumatoid Arthritis & SLE

For IgE-mediated allergic reactions (HSR Type I) what are the common allergens, route of entry, and response for... ...Systemic Anaphylaxis? ...Acute Urticaria (Wheel-and-Flare)? ...Seasonal Rhinoconjunctivitis (Hay Fever)? ...Asthma? ...Food Allergy

All IgE-mediated responses (to extrinsic antigens) involve mast-cell degranulation, but symptoms experienced are different depending if allergen is injected, inhaled, or eaten, as well as the dose of the antigen. *SEE CHART* Shorthand: - Atopic urticaria (hives) - Atopic rhinoconjunctivitis (hay fever): runny, itchy nose and eyes - Asthma: wheezing, cough, chest tightness - Atopic dermatitis (eczema): dry, itchy skin - Food allergies = Acute: Hives, anaphylaxis, flushing, angioedema, oral itching = Chronic: (not all are type I responses) eczema, asthma, diarrhea, vomiting

HSR Type II: Antibody Mediated Hypersensitivity What is the primary mediator of HSR Type II? What 2 things could happen? What are the 3 key factors (...of the many...) of the Classical Complement Activation? What are their functions? What 2 things happen after the IgG-FcγR interaction?

Antibody Mediated Hypersensitivity Type II: Innocuous *Ag's bind to surface of cells -> IgM or IgG* mediated - *Autoreactive Ab's*: Following steps...1) Recruit inflammatory cells. 2) Opsonize. 3) interfere with cell functions. 1. *CLASSICAL COMPLEMENT ACTIVATION*: Opsonize, phagocytose (???), lysis and tissue damage by MAC complex and phagocytes. - Steps: IgG/IgM activates C1 for C4b/C2a adhesion (C4a/C2b leave), then C3b, then C5b (C5a leaves) & C6/C7/C8/C9 for MAC formation. 1a. *C5a*: chemotaxis & activator of neutrophils - C3a also a chemoattractant 1b. *C3b*: opsonin for phagocytosis - I think surplus C3b made after initial MAC lysis opsonizes for phagocytosis. 1c. *MAC*: for osmotic lysis of the cell 2. *IgG-FcγR* Interaction: that leads to... 2a. *Antibody Dependent Cell-mediated Cytoxicity (ADCC)*: by NK cells (via CD 16; Fc) - granzymes and perforins 2b. *IgG OPSONIZES*: mediated phagocytosis

What is Farmer's Lung (Hypersensitivity Pneumonitis [HP])? What form of Farmer's Lung is actually a Type IV HSR? ...what is the presentation of this disease that makes this a HSR Type IV?

Arthus reaction??? 1. Fungal antigen inhaled into lungs of a sensitized individual 2. IC's formed in alveoli (no upper/lower respiratory tract???) 3. Complement fixation leads to cell accumulation, inflammation, and fibrosis. *Chronic Farmer's Lung, where granulomas* are present would be a *Type IV HSR* (bc made by Th1 & macrophages).

Ataxia-Telangiectasia: AT What is the deficiency? What is the defect? What are the 3 signs & symptoms? What are 2 unique factors of AT?

Ataxia-Telangiectasia: AT Deficiency: *ATM gene* Defect: *extreme sensitivity to radiation - because of impaired DNA repair and defective apoptosis* MoI: AR S/S: - *Recurrent respiratory* infections accompanied by *difficulty walking (Progressive cerbebellar ataxia)* - *Oculocutaneous Telangiectasia (abnormal dilation of capillary vessels)* Unique: - *Selective IgA deficiency very common* - *High rate of neoplasia/ leukemia/ lymphoma* - Gene maps to 11q22 long arm that controls a phosphatidylinositol-3-kinase (PI3K) - will be used as a pre-natal test

Atopic Dermatitis (Eczema) = CHRONIC ...what respiratory disease is it compared to? ...what are the allergens? ...what is the primary symptoms? EXTRA: What are symptoms that occur prior to the primary symptom?

Atopic dermatitis (eczema) is the *epidermal equivalent of chronic asthma (TH2 mediated chronic inflammation)*. Allergens: *food and inhalant allergens*, autoantigens; but also frequently, unknown. AD patients may have *other allergic problems* (asthma, allergic rhinitis). Itchy, red (flare???), and often painful areas of skin usually first appear in childhood; lichenification (thickening of the skin) occurs following scratching. During flares, the epidermis swells (spongiosis; wheal formation???) and activated CD4+ memory Th cells are found in the dermis, along with elevated serum IgE. Chronic flares result in *fibrosis (scarring)* of the dermis and thickening of the basement membrane surrounding blood vessels.

What is an Autograft? ...accepted or rejected; immunosuppression)? What is an Isograft? ...accepted or rejected; immunosuppression? What is an Allograft? ...accepted or rejected; immunosuppression? What is a Xenograft? ...accepted or rejected; immunosuppression?

Autogeneic or *Autograft*: a graft from self to self - *Accepted without immunosuppresion* - e.g., skin, stem cell, vein, blood Syngeneic or *isograft*: graft between identical twins - *Accepted without immunosuppresion* *Allograft*: graft between genetically dissimilar individuals; unrelated of the same species - Most common form of transplantation - *Rejected* with immunosuppression - e.g., blood, cornea, heart, lung, liver, kidney, bone marrow *Xenograft*: graft between different species - *Rejected*; our T cells do not do well with other MHC molecules - e.g., pig heart valve

What are the 3 components of an autoimmune disease? Explain each. What is an example of an environmental toxin modifying self-protein to creating a new antigen?

Autoimmune disease *needs 3 components*: 1. *MHC molecules*: Presents the self-antigens 2. No "Tolerances" (and Treg???): *Failure to delete or functionally inactivate self-reactive lymphocytes*. 3. *Additional environmental* and/or *genetic factors*: - Infection: = Ex: Viral (coxsackie—>DM I) or Bacterial infections (Grp A strep—> rheumatic fever) - Susceptibility genes: Few monogenic but most multifactorial - Hormonal influence: Females increased risk - Environmental toxins: Modifies self-protein to create a new antigen. = Ex: Smoking increases peptidyl arginine deaminase (*PAD*) which *citrullinates* Arginine.

What is autoimmunity? What causes autoimmunity? Be specific.

Autoimmunity is a problem of self vs. non-self discrimination (Body attacks Self) Cause: *Failure of tolerance* processes that normally protect the host from the action of self-reactive lymphocytes - *Central* or *Peripheral* tolerance Leads to recognition of autoantigens by autoreactive T cells and/or B cells (autoantibodies)

Scleroderma ...what is the HSR type? What type of disease is scleroderma? (HINT: What is abnormally produced in high quantity in this disease?) What are the autoantibodies in this disease? What are the 2 clinical features of this disease? What are the 2 types of this disease? Be specific on affected areas and their complications.

Both *Type III or IV HSR* - III: *Autoantibodies in immune complexes* Female predominance (4:1); onset 45-65 years Heterogeneous group of *chronic fibrosing diseases* - Macrophages in skin & visceral organs stimulate fibroblasts (via fibroblast growth factor and others) to deposit a lot of collagen. - Fibrosis impairs normal organ function with death resulting from renal failure, respiratory failure, cardiac insufficiency, and/or intestinal malabsorption. - Lower esophageal sphincter tone is due to fibrosis and malabsorption, diarrhea and wasting are due to fibrosis of the small intestine, with decreased motility. Presence of autoantibodies: - *ANA (anti-nuclear antibodies) in 80%* of patients & 30% are RF+ - *Anti-centromere (limited), anti-Scl-70 (Diffuse), anti-Ro, anti-RNP* *Clinical Features*: *Symptoms are highly variable* - Thickening of the blood vessels - Abnormal fibrosis of skin and other organs - *Raynaud's Syndrome* - *Sclerodactyly* Types: 1. *Limited cutaneous*: restricted to skin on hands, arms, face, feet 2. *Diffuse cutaneous*: extensive skin + internal organ(s) - *lung, kidney, heart, GI diseases* = *complications: pulmonary fibrosis; pulmonary hypertension*

XLA: Bruton's Agammaglobulinemia What is the cause of XLA? What is the defect of this cause? What is a sign and symptom of XLA? What is NOT a sign and symptom of XLA and why? What are the serum titers of Ab's of B cells? How would you diagnose XLA? Be specific. EXTRA: What are the limitations? ...treatment? ...unique?

Cause of Deficiency: *BTK gene mutation/ pre-BCR mutation* - FROM BLOCK 2: Pre-BCR signaling via BTK enforces ALLELIC EXCLUSION (one allele expressed, other is silenced); signals good H chain. - Mutation of BTK: X-Linked Agammaglobulinemia - failed signaling (during negative selection?) -> rearrange 2nd chromosome for 2nd H chain but same result -> apoptosis; no maturity as BTK is not present to signal successful H chain made. Defect of Deficiency: *NOT ABLE TO MAKE AB's!* because all the B cell apoptosed during development (couldn't make a viable H chain). Age of Onset: 6-8 months (after mother's Ab's begin to wane) Inheritance: X linked Recessive; XLA FEMALES EXPRESS X WITH BTK- (mutant type), while other X (even if wild type; BTK+) is inactivated. S/s: - Recurrent Staph Pneumonia/ URI's by 2-3 yo - incomplete resolution - *Can handle MEASLES without tissue* (demonstrates ability to clear VIRAL infections) because CTL of the immune response is fine and functional. - *NO tonsils (no B-cell zone) = no lymphadenopathy (which is often seen in infections)* Serum Titers: Low to NO circulating B-Cells - *IgM = [-]*; because a lack of Btk wouldn't even allow Ab's to be made. - IgA = LOW & IgG = low (...what??? I thought Ab's were not supposed to be made???) Dx - *Flow Cytometry/ FACS: Lack of CD19+ cells (pan B-cell)* [know how this would look! - normally to be in middle but in XLA will just take axis of CD3] - But CD3+ intact Limitations: Can NOT receive LIVE vaccines (because cannot control them or build Ab's to them) Treatment: IgIV (not just IgG - all Ig's!) - given weekly to sustain proper Ig levels UNIQUE: female carriers show lymphocytes w/ skewed/ non-random X x-some inactivation (what???)

X-linked Hyper-IgM (XHIGM) What is the cause? What is the defect of deficiency? What are the serum titers? How would you diagnose XHIGM? Be specific.

Cause: *Defect/ missing CD40L (on T-cells)* Defect of Deficiency: *T-cell help is ABSENT* - *NO Germinal Centers* (not giant or not at all???) - because B cells cannot be activated for proliferation *but there ARE B & T-cell zones!* - *NO class switching/ ONLY IgM* and NO ability to signal Macrophages (opportunistic will have easier time infecting) Onset: 10 months old Inheritance: X.R. S/s: increased susceptibility to infections in 1-2 y.o. - Neutropenia (low neutrophil count) - Recurrent upper and lower respiratory infections from opportunistic fungal and viral agents = Pneumocystis Jiroveci, CMV Serum Titers: - *IgM = NORMAL to elevated* - *IgG/ IgA = absent* Dx - *Flow cytometry/ FACS*: CD19+ (B-cells there, just not activated); CD3+ (T-cells there but *not able to bind B-cells due to loss of CD40L*) 1. FACS analysis of activated T cells - *CD25 (= IL-2α*; almost same as IL-2R) is a marker of *activated T cells*; even if there is *no CD40L for B cell activation...T cell met its quota and is still activated*. - *Anti-CD40L* added: CD40L only on T-cells when activating B-cells...triggered by TCR <-> B cell (MHC). 2. Again, there are *no germinal Centers* (not giant or not at all???) in lymph node of patient with XHIGM. Treatment: Ig IV every 3-4 weeks/ BM transplant (sibling???) since defect in T-cell's is life-threatening; passive immunity needed to fight off potential infections. Limitations: NO live vaccines

CHS - Chediak-Higashi Syndrome What is the cause? What is the defect resulting from this cause? What is the sign of CHS?

Cause: *Mutation in LYST (lysosomal TRAFFICKING regulator gene)* Defect: *Impaired chemotaxis, abnormal NK cell activity, giant granules in all cells w/ lysosomes* - NEVER TAKEN UP and DEGRADED - No fusion of cytotoxicgranules w/ membrane= no release of P&G Inheritance: A.R. S/s: recurrent infections bacteria, neurological abnormalities (M.R., seizures) - Oculocutaneous Albinism: *Partial albinism (melanin accumulation inside of giant melanosomes which are related to lysosomes)*

What is the cause of Immediate Transfusion Reaction? Why is blood typing before transplantation/ transfusions is very important? How you can tell who has antibody present?

Cause: *PREFORMED IgM -> complement activation* of blood antigens not compatible with blood type of host. - E.g.: Type A recipient, Type B donor Symptoms of immediate reactions result from massive intravascular hemolysis of the transfused cells. If anti-A binds and causes *AGGLUTINATION* you are positive for the A antigen.

DiGeorge Syndrome What is the cause? What is the defect of this cause? What are 3 symptoms (1 is really a diagnostic test)? What do blood tests show?

Cause: *de novo 22q11 deletion (no 3rd and 4th pharyngeal pouches)* Defect: CATCH-22 - *Hypoplasia or Aplasia of the Thymus gland* abnormal development of fetal cells in neck (face, brain, thymus, heart, aorta) MoI: A.D. S/s: CATCH-22 - Cleft palate, Abnormal facial features, Thymic aplasia, Cardiac defects, Hypocalcemia. - *Valeocardiofacial (small jaw/ underdevelop mouth/ heart problems)* - *Neonatal hypocalcemia* (*tetany/ seizures*): because PTH glands originate from these pouches too, so loss of them means not PTH means decreased calcium reabsorption) - Susceptibility to infection (d/t absence of Thymus) - CXR (diagnostic) shows absent Thymic shadow (no thymus to make a shadow on X-ray) - Recurrent or chronic infection w/ viral, bacterial or fungal organisms Blood tests: - *Low CD3+* (diagnostic) [T-cell response severely diminished (NORMAL B-CELL IMM)] - Mainly normal B-cells...but some may fail to produce high # of B-cells/ no specific - Ab's after vaccination. Tx: Thymic transplant

CGD - Chronic Granulomatous Disease What is the cause of CGD? What is the defect of CGD? What is an example of signs and symptoms? What are the 2 tests used to diagnose CGD? Which test is better? What confirms patient has GCD in a NBT test? Be specific. What confirms patient has GCD in a DHR test? What will neutrophils look like in carrier (mother)?

Cause: Deficiency of *NADPH oxidase* (can't make ROS); neutrophils can't kill anything. Defect: heterogeneous ID - *inability of phagocytes to kill microbes* due to lack of NADPH to make ROS. Mode of Inheritance: X-linked (most common) - mutation in gene encoding gp91 S/s: Recurrent infections (due to lack of active ROS in neutrophils) bacteria, fungi (normal flora *i.e. opportunistic infections*) D/x Tests: 1. NBT test: Activated neutrophils are tested for their ability to phagocytose and reduce NBT. - CGD - Mutant; Unstimulated neutrophils: appear without having *NO BLUE CRYSTALS = Defective NADPH Oxidase = NOT REDUCED = CGD* - Normal (wild-type) - stimulated neutrophils: Reduced NBT seen as dark blue crystals = functional and not CGD. 2. DHR test - *more accurate than NBT*; CGD if no fluorescence. - *Neutrophils must be activated w/ PMA which converts DHR to Rotamine (flourescence confirms reaction complete) (activated to turn NADPH [oxidase???] ON in neutrophils)* = *Goal = should see fluorescence if activated.* - Graph of X-Linked CGD Patient: Same curve post activation = unable to perform reaction; cannot activate neutrophils and remain in resting state. Neutrophils in carrier (mother) has random X-inactivation (some cells mutated and some not).

Complement Activation Pathways What is the classical pathway? What is the MBL pathway? What is the Alternative pathway?

Classical Pathway - C1 & IgG, then C2, C4 - Deficiency: leads to HSR Type III disease (immune-complex disease). MBL Pathway - MBL acts like C1, then into classical pathway (C2, C4); no IgG. - Defiency of MBL leads to bacterial infections. Alternative Pathway - Factor D & Factor P - Deficiency leads to pyogenic bacterial and Neisseria spp. infections but no immune-complex disease. C3 convertase, C3b, C5/6/7/8/9

What are the 2 general classification of autoimmune diseases? Explain each. Again...what distinguishes the different HSR types?

Classification of Autoimmune Diseases 1. *Organ specific*: target a specific organ or gland 2. *Systemic*: target multiple organs HSR Types *Type I* - Allergic response (IgE-mast cell degranulation & eosinophil activity???) to soluble Ag (allergen) (not really seen in autoimmune) *Type II* - Ab specific for cell surface antigens *Type III* - Immune complex disease *Type IV* - T cell-mediated disease

Deficiency in DAF (CD55) and CD59 ...what is the disease? ...what is the normal function of DAF? ...what is the cause of deficiency? ...what is the effect of deficiency? ...what is the sign of this deficiency? C1 Esterase Inhibitor (C1-INH) Deficiency ...what is the disease? ...what is the cause of deficiency? ...what is the effect of deficiency? ...what is the sign of this deficiency?

Defective humoral immune function and continuous tissue damage via a constitutively active complement system due to NO COMPLEMENT-REGULATORY PROTEINS (DAF, CD59, and C1INH). 1. Deficiency in DAF (CD55) and CD59: *Paroxysmal Nocturnal Hemoglobinuria* - *DAF (Delay Accelerating Factor)* Normal Function: *Dissociates C3 convertase*, preventing MAC formation. - Cause of Deficiency: *Mutation in Phosphatidyl Glycan, Class A (PIGA)* so *NO cell surface expression of CD55, CD59* (homologous restriction factor) so it has a *defective GPI anchor* (???). - Effect of Deficiency: *No protective factors on our own RBC's against MAC*; cannot dissociate C3 convertase. - S/s: *Red Urine in morning* (NOT stopping MAC from self- lysis) 2. C1 Esterase Inhibitor (C1-INH) Deficiency: *Hereditary Angioedema (HAE)* - Cause of Deficiency: *Mutation C1-INH (C1-esterase)* - Effect of Deficiency: *No inhibition of C1; not able to stop vasoreactive* ("angio" in HAE) *peptides from causing 'over- exaggerated rxn'* (classical complement pathway???) - Inheritance: A.D. - S/s: *Edema* (literally "edema" in HAE) *in traumatized areas, face, airways, gut, feet, hands. (increased vascular permeability increased fluid out into tissues)*

What do defects in complement problems cause? What are the 3 complement proteins that can be deficient, as well as the effects of deficiencies in the classical pathway? What is the patient more susceptible to with deficiencies in the classical pathway? What happens to the immune-complexes formed due to deficiencies of complement proteins of classical pathway? EXTRA?: What are the 3 complement proteins that can be deficient, as well as the effects of deficiencies in the alternative pathway? EXTRA?: What are the 6 complement proteins that can be deficient, as well as the effects of deficiencies in all complement pathways? ...which is the worst to lose? What are 3 complement-REGULATORY proteins that can be deficient, as well as the effects of deficiencies in all complement pathways?

Defects in complement proteins cause defective humoral immune function and tissue damage Deficiencies in *Classical Pathway*: (Immune-complex. May or may not be on pathogen surface???) 1. Complement Protein: C1, C2, C4 - Effects of Deficiency: Immune-Complex Disease (Ag-IgG/IgM just deposits somewhere???) - Susceptibility to infections with pyogenic bacteria *(pus forming)* - *ICs carried by cells with CRs to spleen and liver for clearance* Deficiencies in Alternative Pathway: (C3b on microbial surface; microbe could be encapsulated) 1. Complement Protein: Factor D, Properdin (FactorP) - Effects of Deficiency: Susceptibility to encapsulated bacteria (which MAC formation would have destroyed) and Neisseria (also encapsulated) but no immune-complex disease. 2. Complement Protein: Factor I - Effects of Deficiency: Similar effects to deficiency of C3 Deficiencies in *all pathways* 1. Complement Protein: C3 (needed in all pathways) - Effects of Deficiency: Susceptibility to encapsulated bacteria (again because no opsonization or MAC to destroy them). - *C3 deficiency is the most serious* and *usually fatal* 2. Complement Protein: C5 - C9 - Susceptibility to Neisseria. Because no MAC (C5 - C9 are the final components that form MAC complex). MAC component deficiencies: - Susceptibility to recurrent meningococcal and gonococcal infection = Neisseria meningiditis = Neisseria gonorrhoeae Defects in complement-regulatory proteins (too much active complement) - Defective humoral immune function and continuous tissue damage via a constitutively active complement immune system. 1. Complement-Regulatory Protein: DAF (CD59) - Effects of Deficiency: Autoimmune-like conditions including *Paroxysmal Nocturnal Hemoglobinuria* 2. Complement-Regulatory Protein: C1INH - Effects of Deficiency: *Hereditary angioedema (HAE)*

Innate Immunodeficiency diseases ...what would a defect in phagocytic cells allow? ...what would a defect in complement components cause?

Defects in phagocytic cells permit widespread bacterial infections. Defects in complement components and complement regulatory proteins cause defective humoral immune function and tissue damage.

BARE LYMPHOCYTE SYNDROME - TYPE I What is the cause? What is the defect from the deficiency? How (Hint: When) is this disease diagnosed? How is MHC II (Th cells)?

Deficiency: *HLA class I deficiency (makes MHC I) due to mutation in TAP1 or TAP2* (no peptides loaded so no endogenous presentation). Defect: *Low to no MHC-I molecules as well as LOW # of CD+ CTL's* Dx: *Not accompanied by particular pathologic manifestations during the first years of life*, although chronic lung disease develops in late childhood. S/S: Chronic infections (starting in late childhood) - Restricted to respiratory tract and extend from upper to lower airway. *Normal expression of MHC class II molecules (normal CD4)*

Wiskott-Aldrich Syndrome: WAS What is the deficiency? What is the defect of WAS? Be specific. What is a sign of WAS? What is the "triad" that occurs in WAS?

Deficiency: *Mutation in Wiskott Aldrich Syndrome Protein (expressed in WBC's and megakaryocytes)* - Facilitates actin polymerization needed for capping and antigen-receptor induced proliferative responses. Defect: *Inability of T-cells to reorganize their actin cytoskeleton* = *Nuclear synapse effected greatly* - *signals are hindered (problems in signal transduction)* MoI: XR S/S: - Defective response to polysaccharides - Susceptible to *encapsulated bacteria (S. Pneumoniae and H. Inf)* *TRIAD*: *PET* THE WASP - *P*yogenic infections - *E*czema: d/t elevated IgE - *T*hrombocytopenia Tx: Bone Marrow Transplant Unique: Hematopoetic stem cells of female carriers exhibit skewed or non-random X- chromosome inactivation.

Omenn Syndrome What is the cause? What is the defect of deficiency? What are the symptoms (3 ~ 4)? What do blood tests show?

Deficiency: *RAG1/2* OR *Artemis (loss of variability)*; VDJ recombinase. Defect: *Development of TCR is upset* (B cells too...How would they even live if they can't undergo tolerances???) - *T-cells* that DO make it WILL expand...but will *all have same specificity!* Inheritance: Autosomal S/s: Papular scaly *rash* covering entire body at 1 mo. of age. - *Eczematic & bright red!* - *No Thymic shadow!* - *LN's enlarged* (...Why if there are no T cells or B cells???) Blood tests: - *IgE elevated (SCID with hypereosinophilia)* (...but BCR's are not effected???) - Neutrophils/ lymphocytes *LOW* - *NO CD19+* (How can there be elevated IgE, and no B cells???) - Few CD3+ (What??? How can there be T cells??? Anergic???) - Mostly see *oligoclonal CD4+ cells* Prognosis: POOR Tx: BM transplant

Bare Lymphocyte Syndrome Type II (BLS Type II) What is the deficiency? Be specific. (HINT: Compare to BLS Type I) What is the defect of BLS Type II? Be specific. What about MHC I molecules? Which is worse, BLS Type I or BLS Type II? Why?

Deficiency: *genes controlling MHC II expression (CIITA or RFX)* Defect: *deficient CD4+ T-cells - Hypogammaglobulinemia* - Since Th2 is affected, *No class switching/no plasma cells* of B cells. - Since Th1 is affected, *Treg deficiency as well* Dx: lack of CD4+ T-cells on FACS/ flow cytometry Serum levels of Ig's is LOW (IgM may be high as seen before) S/S: poor humoral immunity!! *Normal expression of class I molecules!* *MORE Severe than Type I because No T-cell help Ab's with TP*; Th are really the at the center of helping/activating CTL's, B cells, and macrophages.

CVID - Common Variable Immunodeficiency ...what is the problem (...deficiency)? ...what is the defect of the deficiency? When does this disease take effect or become symptomatic? How would you treat CVID? What is unique (didn't sound unique to me) about CVID?

Deficiency: B cells get problematic over time. - *B-cells*: CD19+ normal...but levels *decrease at later pt. in time* (~20 y.o.) - T-Cells: CD3+ ciruclating normal - Fewer switched B-cells and memory cells = can get a response in B-cells but it's NOT a long lasting one. Defect of Deficiency: *Low levels of serum Ig's over time* Onset: *Later on in life - 20s-30s -NOT in infancy!!!!*; "..later on in time" MoI: A.R. S/s: Due to loss of Ig's, increased susceptibility to chronic and recurrent sinopulmonary infections Tx: Antibx/ *IV-Ig* Unique: *Family history of CVID or Selective IgA deficiencies.*

Selective IgG Subclass Deficiency NOT HIGH YIELD What is the deficiency...in title? What is characteristic about the inheritance? What is unique about the disease?

Deficiency: UNKNOWN - *Deficiency in 1 or 2 IgG subclasses* where other immunoglobulin levels are normal and suffer recurrent infections. Defect: *Less severe than XLA and CVID* - Selective IgG1 deficiency: rare - Selective IgG2 deficiency: common in children - Selective IgG3 deficiency: common in adults - Selective IgG4 goes with IgG2 deficiency Inheritance: NO clear pattern (*some family will have IgA Def, or CVID*) Dx: Normal B and T-cell levels; *low IgG for age* (but other Ig's are OK) S/s: - Hx of recurrent ear, sinus, lung infections Tx: Antibx Unique: - **Some children will outgrow this ID** - *IgG2 deficiency*: - *Unable to produce Ab's when immunized w/ polysach vacc's* IgG1 & 3 important for complement activation IgG2 can "fill in" for 1 & 3 and necessary for response to conjugate polysaccharide vaccines

Development of Th1 Cells is associated with which HSR? What are the 4 effector functions of CD4 Th1 cells? Development of Th2 Cells is associated with which HSR? What are the 4 effector functions of CD4 Th2 cells?

Development of TH1 Cells: *Correlates with HSR Type IV - Delayed Type/ Cell-Mediated* - IFNγ (from macrophage...or DC) & IL-12 (from NK cell) differentiates Th0 to Th1. - Gene involved it T-bet. - After Signal 1 (TCR-MHC II) & Signal 2 (CD 28-B7), secretes cytokine IL-2 for (autocrine) self proliferation. - *Effector Functions* 1. Macrophage: activation (IFN-γ), against bacteria. (*HSR Type IV*) 2. B Cell: IgG isotype switch (IFN-γ) to opsonize bacteria. (*HSR Type IV*) 3. CTL: Activation (IL-2, IFN-γ), against IC viruses or bacteria. (*HSR Type IV*) 4. Neutrophil: activation (LT???, and TNF-α) against bacteria. (*HSR Type IV*) Development of TH2 Cells: *Correlates with HSR Type I - Immediate/ Allergic.* - IL-4 (autocrine signal) for differentiation of Th0 to Th2. - Gene is GATA-3. - After Signal 1, and Signal 2, secretes cytokine IL-2 to proliferate. - Effector functions of CD4 Th2 cells 1. IgE production via IL-4 (*HSR Type 1 - Immediate/ Allergic*), (and IL-13???). 2. Eosinophil activation via IL-5. (*HSR Type 1 - Immediate/ Allergic*) 3. Mast cell degranulation via IL-4 (*HSR Type 1 - Immediate/ Allergic*). 4. Suppresses macrophages via IL-4, and IL-10.

Type I Hypersensitivity Reactions What are the 2 reactions required to positively diagnose a patient as having HSR Type I?

Diagnosis 1. "Wheal and Flare" Reaction 2. RAST (RadioAllergoSorbent Test)

What dermal diseases are associated with HSR Type I? What are the immediate, and late-phase symptoms of dermal HSR Type I diseases? For inhaled allergens, what generally happens as a result of HSR Type I? For inhaled allergens, what causes this HSR Type I response during an immediate phase? ...late-phase?

Diseases of HSR Type I 1. *ATOPIC URTICARIA (HIVES)* 2. *DERMATITIS (ECZEMA)* Allergic (dermal???) reactions divided into immediate & late-phase response. 1. Immediate Response - *WHEAL & FLARE*: allergic reaction develops ~1 - 2 mins of superficial injection of antigen into epidermis and lasts ~30 mins. 2. Late-Phase Response - *WIDESPREAD EDEMA*: develops ~8 hrs later & persists for hrs. Similarly, response to inhaled allergen is divided into early & late responses. - *PULMONARY ASTHMA*: narrowing of airways via constriction of bronchial smooth muscle. Measured as *FALL IN FORCED EXPIRED VOLUME (FEV)* of air in 1 second. 1. Immediate Response: *MINUTES* after antigen inhalation and then subsides. Caused by *DIRECT EFFECTS ON BLOOD VESSELS & SMOOTH MUSCLE* by mediators such as *HISTAMINE* released by mast cells. 2. Late-Phase Response: *~8 HRS* after antigen challenge, also results in a fall in FEV. Caused by effects of an *INFLUX OF INFLAMMATORY LEUKOCYTES* attracted by *CHEMOKINES* and *MAST CELL MEDIATORS* released after immediate response.

What other form of testing is RAST similar to? What are the general 3 steps (layers) for this other test?

ELISA 1st layer: Allergen 2nd layer: Patient's serum *3rd layer: Enzyme linked anti-IgE* - Substrate for color change or fluorescence

HSR Type IV What occurs during granuloma formation? What are 4 other examples of HSR Type IV? What occurs during celiac disease? ...what gene is involved? ...antigen formation? What occurs during contact dermatitis? ...antigens? ...clinical manifestations? What occurs during tuberculin reaction - PPD or Leprosy test? ...antigen involved? ...clinical manifestation? ...measuring...? What occurs during autoimmune diseases?

EXAMPLES: 1. Granuloma: Caused by TB, leprosy - Can't clear organism; activated macrophages surrounded by Th1 - *Chronic* - 4 weeks reaction time 2. *Celiac Disease*: Villous atrophy. 2a. *HLA-DQ2/8* genetic susceptibility (just like DM-I); 2b. Gluten (*gliadin*) degrades to resistant fragment, enters gut tissue transglutaminase deaminates (gln—>glu) 2c. *Naive T cell responds to deaminated peptide* Following 3 examples have 48-72 hrs reaction time (unlike HSR Type I)... 3. Contact Dermatitis: Presents as eczema (so like HSR I Dermatitis but due to T cell damage???). - Antigens Involved: Due to haptens (poison ivy), small metal ions (nickel), or synthetic (*rubber, cosmetics*, bandages) - Clinical Manifestations: Vesicular skin lesions, pruritis, rash 4. *Tuberculin Rxn - PPD or Leprosy test*: measuring size of *induration*. - Antigen Involved: TB protein; PPD (Purified Protein Derivative) - Clinical Manifestations: Indurated skin lesion - Measure size of induration: Local skin swelling (erythema, induration, cell infiltrate, dermatitis). Same rxn to insect venom. 5. Autoimmune diseases** - Type I DM, Hashimoto's Thyroiditis, MS

What is an Epitope? What can happen in regards to epitope recognition, during the course of an immune response? Give an example. What are the 2 forms of epitope spreading? Describe each.

Epitope: Part of Ag molecule to which Ab attaches itself During the course of immune responses, including autoimmune responses, the response expands or "spreads"; *different epitopes are recognized at different stages of the disease* - Ex: *Tissue damage releases other Ag's, Ab response to those antigens* *Inter*molecular epitope spreading: *Response spreads to epitopes on different antigens.* *Intra*molecular epitope spreading: *Response spreads to different epitopes on the same antigen.*

What is the normal PEFR? What is FEV during the immunopathophysiology of asthma? What causes the 2 separate FEV drops?

FEV - forced expiratory volume PEFR - peak expiratory flow rate Normally at *PEFR (400 L/min)*, but *FEV DRAMATICALLY DROPS* (<100 L/min) on 2 occasions. (Due to bronchoconstriction by leukotrienes???). 1st. Immediate (~30 mins): *MAST CELL DEGRANULATION* causes FEV drop. 2nd. Late phase (~8 hrs): *Th2 CYTOKINES* (continued???) & *EOSINOPHILS* causes FEV drop.

What generally occurs during Bone Marrow (HPSC) Transplant Graft vs Host Disease - GVHD? What are the 3 steps of GVHD? What are 4 symptoms ("stages") of GVHD? What can exacerbate GVHD?

GVHD (*Engrafted T cells attack host*) 1. Allogneic (alloreactive) hematopoietic cell transplant contains mature & memory T cells. 2. T cells circulate in blood to secondary lymphoid tissue. Alloreactive cells interact with dendritic cells and proliferate. - In this case, the foreign peptide is the host MHC that will be presented by host-dendritic cells (Why would host DC cells do this???). 3. Effector CD4 & CD8 T cells enter tissues inflamed by conditioning regimen (eg radiation) and attack tissue w/ the MHC that it has recognized as foreign, causing further tissue damage. *Four stages of GVHD depending on severity* *1. Rash* *2. Jaundice (rise in serum bilirubin)* *3. Diarrhea* *4. Abdominal cramps* Chemotherapy or radiation: kills sites of rapidly proliferating cells, and exacerbates GVHD (good or bad???). - When alloreactive T cells go there, they kill cells presenting with "foreign" (host) MHC.

Hemolytic Disease of the Newborn (HDNB) -Erythroblastosis fetalis Is the mother RhD + or -? ...the fetus? Why is the 1st child okay? What happens during birth of 2nd child?

HDNB Conditions: *RhD - mother, RhD + fetus* HDNB Sensitization & Activation 1. Sensitization Phase; 1st Pregnancy: 1st baby is okay because mother is *sensitized at parturition of 1st child (sensitization phase).* - Mother's immune response is now primed (*Anti-Rh+-IgG capable of transplacental*) for next child. 2. 2nd Subsequent Pregnancy: with another Rh+ fetus, maternal *Anti-Rh+-IgG's crosses placenta & attacks (lyses) Rh+ fetal RBC's causing hemolytic anemia*. EXTRA (SUMMARY): **need an Rh- mom, carrying a Rh+ baby... 1st baby will be fine, but this is the sensitization phase...now she will make Ab's against the Rh and if she has another Rh+ baby these Ab's cross placenta and kill the baby

Acquired immune deficiency syndrome: AIDS What is HIV? What cell type does it primarily infect? What co-receptor confers resistance to HIV? When does replication of HIV occur? What 2 opportunistic pathogens take advantage of an HIV infection?

HIV is a *retrovirus* Infects *CD4 T cells* and macrophages. A genetic deficiency of the co-receptor *CCR5 confers resistance* to HIV infection in vivo. HIV RNA is transcribed by viral reverse transcriptase into DNA that integrates into the host-cell genome. *Replication* of HIV occurs *only in activated T cells*. Lymphoid tissue is the major reservoir of HIV infection. An immune response controls but does not eliminate HIV. *The destruction of immune function (through T cell infection) leads to susceptibility to opportunistic infection and eventually to death.* - *I.e. Pneumocystis pneumonia and Kaposi's sarcoma* (HHV-8 associated) HIV accumulates many mutations in the course of infection, and drug treatment is soon followed by the outgrowth of drug-resistant variants.

What is an HSR II Non-Cytotoxic disease? What occurs during Grave's Disease? ...agonistic or antagonistic? What occurs during Myasthenia Gravis? ...agonistic or antagonistic?

HSR II Non-Cytotoxic Diseases: Abnormal physiologic responses due to interference with cellular functions (stimulate or block self-receptor) but no inflammatory response occurs. 1. Grave's Disease: Ab chronically *stimulates TSH-R* for Thyroid Hormone production (T3/T4). - *agonistic* 2. Myasthenia Gravis: Ab *blocks AChR*. - *antagonistic*

Inflammatory Bowel Diseases What generally is the immune response of IBD? What is the cause of Crohn's Disease? Where can Crohn's Disease occur? What is the ulcerative colitis? Where does ulcerative colitis occur? What generally causes ulcerative colitis?

HSR TYPE??? *In IBD*, mucosal barrier becomes compromised resulting in *expansion of Th17 cells* and UI Th17 - Anti-fungal - Differentiation: TGF-β, IL-6, IL-21, IL-22, IL-23 - Cytokines Secreted & Function: IL-17 (mediates inflammation; how???), and IL-22 (Maintains mucosal barrier). 1. Crohn's Disease Cause: - Abnormality of mucosal T cell regulation associated with *IL-23 receptor* (differentiates Th0 to Th17) polymorphisms and/or mutated *NOD2 gene* and a high fat/sugar diet = NOD2: aka caspase recruitment domain-containing protein 15 (CARD15) or inflammatory bowel disease protein 1 (IBD1) Symptoms: abdominal pain, blockage, failure to grow, excessive stools, flatulence - Lesions in *any part of gastrointestinal tract (mouth too)* 2. Ulcerative colitis - Common in USA - *Continuous* mucosal inflammation - Limited to *rectum/colon* - Cause: Associated with *IL-23* receptor (differentiates Th0 to Th17) polymorphisms

What is the (best???) cure for HSR Type I? What is desensitization? How long does desensitization take?

HSR Type I resolved by desensitization. Desensitization: Given small controlled doses of Ag, resulting in INCREASING IL10 -> increasing IgG, and decreases responsive T cells as well as IgE; BUILD A NORMAL TH1 RESPONSE by slow reversal of Hygeine Hypothesis. - IgE arms mast cells but IgG doesn't. - Main Idea: IgG binds allergen before IgE, preventing mast cells or Treg involvement. Wouldn't this just be an HSR Type III now (immunocomplex)??? If HSR type III (deposit & inflammation), better than if HSR type I (systemic edema)??? Full desensitization can occur as early as 3 months, but may take 2 years to be maximal.

Is HSR Type I a cell-mediated or humoral mediated hypersensitivity? What are the 3 general steps to HSR I? Describe each step.

HSR Type I; Antibody Mediated Hypersensitivity 1. *SENSITIZATION*: Th2 response induced by allergen to secrete IL-4, IL-13, and TNF-a, causing *B-CELL ISOTYPE SWITCHING TO IgE*. 2. *EARLY PHASE*: IgE induced by allergen for *MAST CELL DEGRANULATION* 3. *LATE PHASE*: IL-5, Eotaxin = *EOSINOPHIL PRODUCTION* - As well as chemotaxis (chemo-attractant; CXCL8) of eosinophils, neutrophils, and monocytes (all with FcεR) to site of activation, causing tissue damage, etc.

Systemic Lupus Erythematosus (SLE)... ...HSR Type? ...significance of SLR? ...2 genetic risk factors? ...what is the environmental trigger? In regards to SLE... ...why is SLE difficult to diagnose? ...regardless, how could we diagnose? What are 2 (of the many) clinical manifestations (symptoms) of SLE? Be specific on 1 of the symptoms.

HSR Type III - Immune Complex disease Systemic Lupus Erythematosus - Autoantigen: DNA, histones, ribosomes, snRNP, scRNP - Consequence: Glomerulonephritis, vasculitis, arthritis *Most common autoimmune rheumatic disease* Genetic Risk: - Concordance rate for identical twins is 60% (bc epigenetic factors; eg UV light) - Genetic *complement deficiencies* (C1q, C2, C4) - *HLA-DR2* (serotype) in African-Caribbean population Environmental trigger: *UV light in subset of SLE* Dx: *Difficult to diagnose as highly variable symptoms & severity; also episodic*. - *ANA (anti-nuclear Ab)*: *NOT specific for Lupus (many autoimmune diseases)*. - Abs: *anti-dsDNA, anti-SnRNP, or Sm (Smith) antigen (specific for Lupus)*. Clinical Manifestations: Due to deposition of IC's into... 1. Blood Vessels (-> Vasculitis): IC's lodged in vessel wall can't be taken up. Neutrophils release enzymes ("frustrated phagocytosis"), destroying vasculature. - *Malar/Butterfly Rash*: Skin hemorrhage from *damaged blood vessels*. 2. Glomeruli (-> Glomerulonephritis): *Kidney dysfunction* 3. Joints (-> Arthritis). Other Clinical Manifestations: - Pleurisy, fever. - Weakness, anemia, thrombocytopenia. - Memory loss, headaches, confusion, seizures.

Celiac Disease (Gluten-sensitive enteropathy) What is the HSR Type? What is the cause of Celiac Disease? Be specific. What other gene is associated with Celiac Disease? What is the mechanism for Celiac Disease? How would celiac disease be diagnosed?

HSR Type IV Cause: Immune-mediated enteropathy caused by sensitivity to *α-gliadin* of gluten in genetically susceptible (*HLA-DQ2 or HLA-DQ8* serotypes) individuals NOD2 somehow related too. Aka caspase recruitment domain-containing protein 15 (CARD15) or inflammatory bowel disease protein 1 (IBD1) Celiac Disease Mechanism: 1. *α-Gliadin*: Protease-resistant *α-gliadin* peptides (from gluten) induce stress response in enterocytes. 2a. α-Gliadin Gut Entry: Stressed enterocytes secrete *zonulin* which disrupts tight junctions allowing α-gliadin peptides to pass into lamina propria. 2b. Stressed enterocytes secrete *IL-15* which *activates* innate intraepithelial lymphocytes (IELs) 3. *IELs kill* MIC-A/MIC-B expressing enterocytes 4. Tissue *transglutaminase (tTG)* released from lysed enterocytes modifies α-gliadin peptides 5. Modified α-gliadin peptides are presented to CD4 T cells and induce Th1 response - CTLs activated to kill enterocytes - B cells activated to secrete antibodies against antigens released from enterocytes (tTG) and α-gliadin (IgG and IgA) Diagnostic: *Anti-tissue transglutaminase antibodies*

Rheumatoid Arthritis (RA) What is the HSR type? What is the cause? What is the mechanism? What are the clinical features? How would you diagnose RA? What are the treatments?

HSR Type IV -> HSR Type III Cause: Autoreactive CD4+ *Th1 cells & Th17 cells* against undefined synovial tissue autoantigen. Mechanism - Synovitis: invade/damage cartilage, followed by bone erosion & remodelling leading to *joint deformity/destruction*. 1. Unknown trigger (IgG-IgM immunocomplex???) sets up initial focus of inflammation in synovial membrane, attracting leukocytes into the tissue. 2. Autoreactive CD4 T cells activate macrophages, resulting in production of pro-inflammatory cytokines and sustained inflammation. - *Th1: activates macrophages (TNF-α) sustaining inflammation* - *Th17*: IL-17 promotes *neutrophil* production and recruitment. = Neutrophils: Infiltrate & release degradative enzymes (Proteinases & collagenases) which damage cartilage, ligaments, & tendons. 3. *TNF-α*: Macrophages induced by *IL-17* of Th17 to secrete TNF-α. TNF-α *activate fibroblasts & osteoclasts* to secrete enzymes (*MMP = Matrix Metalloproteinases*) that destroy cartilage and bone. *Clinical Features*: *Synovitis* & *chronic, episodic inflammation of joints* - *Pannus*: Mass of synovium and synovial stroma consisting of inflammatory cells (mainly chronic), granulation tissue, and fibroblasts which grows over the articular cartilage and causes erosion. - Joint stiffness (decreased mobility), pain, swelling, loss of function, disability/deformity, hematological, cariovascular, respiratory diseases. Mediators of inflammation: IL-1, TNF-α, prostaglandins & leukotrienes (mast cell/eosinophils??? HSR Type 1???). Diagnosis: *No true Diagnostic tests for RA, but*... - Can base on clinical assessment; X-ray - *IgM Rheumatoid Factor test*: *Detection of IgM RF (IgM anti-IgG)* = *Prognostic, NOT diagnostic marker!*: ~70% *Seropositive RA* (IgM RF) means 30 % of RA patients don't have IgM RF. - *New test for autoantibodies against cyclic citrullinated peptides (anti-CCP Abs) ... ~90% specific for RA* *Treatments*: - Immunosuppressive drugs: corticosteroids, DMARDs, NSAIDs - *TNFα inhibitors*: *(Infliximab, Adalimumab), Etanercept TNFR-Ig* - *Anti-CD20 mAb*: Rituximab (*Rituxan*). Lysis of B cells by NK cells involved in IC formation. - Abatacept (Orencia) CTLA4-Ig fusion protein Others: - Anakinra - Kineret recombinant IL-1 receptor antagonist - Tocilizumab humanized anti-IL-6R antibody

How is HSR Type IV related to HSR Type I? Why is HSR Type III called serum sickness?

HSR Type IV can be mediated by Th2 cells (really???), which secrete cytokines (IL-4 & IL-13) that induce B cell isotype switch to IgE. *IgE IS MEDIATOR OF HSR TYPE I.* HSR Type III was originally called serum sickness - Serum Sickness: forms *IMMUNE COMPLEXES THAT CIRCULATE TO DISTAL REGIONS* and deposit. Highlighted HSR Type IV, column 2. Red arrow starting from this column to only column for HSR Type 1.

Is Type IV HSR cell-mediated or humoral? What are the 2 forms of HSR Type IV, and what do each involve (cells/gross formation)?

HSR Type IV is Cell Mediated. 1. Delayed Type Hypersensitivity - involves Memory Th1 cells & Macrophages - GRANULOMA 2. Contact Hypersensitivity - involves CD8+ CTL

What are treatments for allergic disease based on... ...mediator action? ...chronic inflammatory reactions? ...IgE binding to mast cell? Be specific.

Highlighted Rows: Mediator action, chronic inflammatory reactions, and IgE binding to mast cell. Ignore crossed out

Where do HSR III Diseases normally deposit? For Serum Sickness... ...what type is the deposit? ...signs and corresponding locations? (Be specific) ...cause? For Arthus reaction... ...what is the deposit? ...cause? ...test type (Be specific about response.)? ...in terms of response, what does this mean in terms of (inactive) vaccination? For Post-strep Glomerulonephritis... ...what is the IC composed of? ...what does the Biopsy/DIF show?

IC's typically deposit in joints, kidney, and vasculature. 1. Serum Sickness: IV deposit - S/s & Locations: *arthritis (JOINTS), vasculitis (VESSELS), nephritis (KIDNEYS)* - Cause: *Administration of anti-toxin (horse anti-snake venom) complexes* (with toxin antigen), *builds-up and deposits, resulting in hemorrhaging & urticaria* - Resolves: when foreign protein/toxin cleared from the system 2. Arthus Rxn: ~Subcutaneous deposit - *IgG in skin response* (from sensitization), *forms IC's locally. C5a induces mast cells (basophils too???) to degranulate (↑vascular permeability) & neutrophils to infiltrate (cause inflammation)* - Cutaneous skin test: *local* inflammatory response (*farmer's lung, fungal ag's*) - Can occur at site of *Tetanus Booster (injected) (1-2 hours* - not minutes...or days) 3. Post Strep Glomerulonephritis: Strep Ag's + Anti-streptococcal antibodies = *Immune Complex* - Biopsy/ DIF: shows *lumpy/bumpy deposition pattern is positive, as opposed to linear pattern goodpasture type III*.

What is the HSR Type I clinical response of allergen administration if... ...IV administration? ...Subcutaneous administration? ...Penetrating skin? ...Inhalation? ...Ingestion? What is the most severe response? Explain this response. What would treat symptoms of this severe response?

IV admin: mast cell degranulation (histamine, TNF-a and leukotriene release) causes increased permeability, resulting in *anaphylactic shock*. Subcutaneous: local release of histamine resulting in *wheal and flare* Penetrating skin: causes *atopic eczema* (genetic predisposition) Inhalation (ex. Pollens) - Upper respiratory (larger particles): *allergic rhinitis: sinusitis and hay fever* - Lower respiratory (smaller particles): *asthma (acute = mast cell, chronic = Th2)* Ingestion (food and drugs ex. Peanuts shellfish): *vomiting and diarrhea*; dissemination = hives/urticaria, anaphylactic shock or atopic eczema (exception: *GLUTEN IS TYPE IV*) Most severe response is *anaphylactic shock*: - *HISTAMINE*: *DILATED VESSELS* causing blood flow out of capillaries and into surrounding tissues (*SEVERE HYPOTENSION*). = *TX for drop in blood pressure is EPINEPHRINE because promotes vasoconstriction to increase blood pressure to near normal (SNS)*. - *LEUKOTRIENES*: lead to *BRONCHOCONSTRICTION* (hence why you don't give NSAIDS to an asthmatic patient - they would produce too much leukotrienes and narrow an already narrow airway).

Why do we give an IgG type Rhogam, rather than IgM type Rhogam, if the IgG type Rhogam can pass the placenta (mild fetal hemolytic anemia), even if it is a little?

If we used Anti-Rh+ *IgM there would be no negative FcR activity* (ITIM?). - *Fcγ-R is a negative (inhibitory like ITIMs???) receptor. Fcμ-R is NOT.*; FcγR prevents activation of B cell, FcμR does not. You only need enough IgG Rhogam to bind, for negative mechanism to be induced and prevail. - IgM anti-Rh doesn't work it would need to bind every Rhogam seeing as IgM is on every B cell and IgG is the one the woman has, IgM is only in primary response. ???

What is the timeframe (immediate, intermediate, delayed) of the 4 HSR's? What is the basic info of HSR I (general descriptive term, cause, & timeframe)? What is the basic info of HSR II (general descriptive term, cause, example)? What is the basic info of HSR III (general descriptive term, cause)? What is the basic info of HSR IV (general descriptive term, cause)?

Immediate - Type 1: Anaphylactic Intermediate - Type II: Antibody-Med - Type III: Immune Complex Delayed - Type IV: Cell-Mediated Type I HSR: Anaphylactic. Caused by interaction of *SOLUBLE ALLERGENS WITH IgE, CAUSING MAST CELL DEGRANULATION*. - PLEASE NOTE THAT TYPE I HAS A DELAYED PHASE AS WELL IN WHICH EOSINOPHILS AND BASOPHILS ARE BROUGHT IN. Type II HSR: Antibody-mediated. Mediated by *IgG MADE AGAINST NEW EPITOPES OF CELL-SURFACE PROTEINS* caused by chemical modification. - Example: Antibiotic drug penicillin forming a new epitope by chemically modifying a human cell-surface protein. Type III HSR: *IMMUNE COMPLEX*. Mediated by IgG made against a soluble foreign protein, which form immune complexes that are deposited in tissues and become subject to complement fixation and phagocyte attack. Type IV HSR: *CELL-MEDIATED*. Caused by CD4 T cells responding either to epitopes of foreign proteins or peptides derived from chemically modified human proteins, presented by MHC class II.

In Early (Immediate) Phase of HSR I... ...how soon do symptoms occur? ...what initiates this (elicitation) phase? ...what are the components of granules released by mast cells? (HINT: At least 3 of the 5 listed) What are the PRIMARY symptoms of granules released by mast cells? What is the cause of the symptoms of this phase?

Immediate (Early) Phase of HSR I: Symptoms occurs within *MINUTES* Cause: Re-exposure; binding of allergen to IgE on *Mast cell triggers degranulation (release of mediators)*. Mast cells - Granule Components 1 & 2. Toxic Mediators: *Histamine* (dilates vessels) & *Heparin* (kinin pathway = pain and permeability) 3. Serotonin 4 & 5. Remodel CT Matrix; Tissue Damage: Carboxypeptidase & *Tryptase* *SYMPTOMS ARE DUE TO DEGRANULATION* components released when Mast cells IgE cross-link w/ Ag: - Initial Symptoms: Pain, itchiness, and increased permeability. - Primary Symtpoms: *Wheal (edema) & Flare (erythema)*; Hives & Urticaria - Other Related Symptoms: Diarrhea. Swelling. Mucus secretion. ↑ blood flow & ↑ increased permeability. Hypotension & anaphylactic shock..

For Adaptive Immunodeficiency diseases... What can a defect in antigen receptor gene arrangement result in?

Immune deficiencies can be caused by defects in B-cell or T-cell activation and function. Defects in T-cell development can result in severe combined immunodeficiencies. SCID can also be due to defects in the purine salvage pathway. *Defects in antigen receptor gene rearrangement can result in SCID (T cells that cant fulfill their actions)* Defects in signaling from T-cell antigen receptors can cause severe immunodeficiency. Genetic defects in thymic function that block T-cell development result in severe immunodeficiencies.

In intermolecular spreading... ...what is the process? ...how many T cells are used to activate how many B cells? Why? ...What is a common example of intermolecular epitope spreading? In intramolecular epitope spreading... ...what happens to antibodies? ...what is an example of intramolecular epitope spreading? Explain this example. ...what occurs during Pemphigus? ...what causes this spread?

Intermolecular epitope spreading: Response spreads to epitopes on different antigens. - Process: 1. Ongoing tissue damage during chronic inflammation (by T cells) releases many 'sequestered' self antigens (previously unseen) from tissue. 2. Once seen...ID'ed as foreign & attacked; APC presents to T cells in lymph nodes - A *single T cell* can activate *multiple B cells* specific for *different components* (epitopes) of a molecular complex (made of different antigens). How (since a Th0 has 1 TCR type for 1 epitope type)??? - Ex - *Primarily in Type IV HSR* - Anytime 'non-pathological' Ab (self) is seen, it usually indicates INTERmolecular spreading. Intramolecular epitope spreading: Response spreads to different epitopes on the same antigen. - Early Ab's are NOT pathogenic; *Non-pathogenic antibodies progress to pathogenic ones* - Ex - *Pemphigus*: *Starts from EC5 epitope and works its way down towards EC1 (towards Basal Lamina)*; Ab's made against distal epitopes (away from EC5) are pathogenic. = Spread is due to Ab's against previous EC# having bound that particular EC. = *Ab's then created against available epitopes (next EC# down)* - Pemphigus only becomes symptomatic when the FINAL EC1-2 epitope is recognized (because then the bridge is broken [???]).

Severe Combined Immunodeficiency Syndromes (SCIDS) What happens to the number of lymphocytes? Use the basic medical term. What are the 5 types (really 6) of SCIDs? For features of SCIDs... ...what lymphocyte types are deficient? ...when do SCID problems present? What are the 4 prominent signs? ...what is the condition of the thymus? What is the treatment for SCID?

Introduction: - Infants who died of infection before their first or second birthdays. - *Profound lymphopenia* - Difference in inheritance patterns; more than one cause for this condition = XR and AR - All types display low lymphocyte count - Focus on ... = X-linked and AR = Different problems...same phenotype Types: 1. *ADA or PNP deficiencies* 2. *X-linked SCID - gamma common chain (γ-chain) deficiency* 3. *SCID - Jak 3 deficiency* 4. *Bare lymphocyte syndrome Type II* 5. *Omenn syndrome - RAG1, RAG2, or Artemis deficiency* Features of SCIDS: KNOW THESE! - Syndromes defined as immunodeficiency affecting more than one leukocyte lineage. - Rare, fatal syndromes characterized by severe *deficiencies in B and T cell function.* - *Present by 3 months of age with persistent thrush or hyperpigmented rash, intractable diarrhea and infections with opportunistic pathogens*, such as Pneumocystis jiroveci. - Profound *lymphopenia, no CMI, no humoral immunity*. - Incapable of respondingto specific antigens. - Hypoplastic lymph nodes. *Dysplastic thymus*. - Low serum immunoglobulins. - FATAL W/ OUT BONE MARROW TRANSPLANT

What is JAK3 supposed to do? Why do we still get B cells? Why not T cells (my theory, not explained in tutoring ppt)?

Janus Kinase 3 (Jak3): Main signal transducer for the common gamma chain (γc of *IL-2Rγ on B cells = CD132*) shared by multiple cytokine receptors (notably *IL-7R*). - Basically any receptor with a γ chain has Jak3 too, so if the receptor is being stimulated, the signal dies at Jak3. TOO VAGUE: Basically other cytokines (IL-4, and others) fill in the role of Jak3, allowing us to still make B cells. Eg: IL-7R has γ, so it has a Jak3. This actually affects B-cells (as opposed to γ of IL-2R which affects T cell activation) due to its role in VDJ joining. - So since other cytokines step in place for Jak3 being deficient, VDJ joining can still occur and help B-cells still be made. The same cannot be said for T cells...at least there is no mention how IL-2R (which uses γ, hence uses Jak3) is compensated for so it can activate/proliferate T cells.

In Late (Delay) Phase of HSR I... ...how soon do symptoms occur? ...what is the primary happening of the phase? ...what mediators in Th2 stimulate eosinophil production & recruitment? What second wave mediators do Eosinophils or Mast cells produce to cause inflammation and tissue damage in an allergic reaction? Be specific on their actions. What are the "continued cytokines released"? (HINT: 2 cells, 4 cytokines). Include intent of cytokines if possible. What is the primary symptoms during the Late (Delay) Phase of HSR I?

Late (Delay) Phase of HSR I: Symptoms take *HOURS* - *EOSINOPHIL PRODUCTION*: Th2 secretes *IL-5 & eotaxin* for ↑eosinophil production & recruitment respectively. Inflammation and tissue damage in allergic rxn due to Eosinphil's Second Wave of Mediators: 6 - 24 hours post exposure 1. *CXCL8 (aka IL-8)*: Chemotaxis of leukocytes (neutrophils for sure). - (neutrophils, & monocytes too???) 2. *IL-3, IL-5, GM-CSF*: Upregulate own production (just eosinophils???) 3. *LEUKOTRIENES & PROSTAGLANDINS*, metabolites from *ARACHODONIC ACID*: - Chemotaxis for leukocytes, eosinophils, and CD4 T cells (Th1 &/or Th2???) - (Made by eosinophils or mast cells???) Continued Cytokine Release (over hours): 1. *MAST CELL STIMULATED* (since immediate binding until late) 2. Th2 Cells continue secreting cytokines - *B CELL ISOTYPE SWITCH: VIA IL-4, IL-13 = IgE* - *EOSINOPHIL PRODUCTION & ATTRACTION*: via *eotaxin (chemotaxin) & IL-5 (stimulates production)*. Late phase symptom: *Wide spread edema*; general swelling

What is the direct form of MHC (Major Histocompatibilty antigens) allorecognition? ...MHC I or MHC II? What is the indirect form of MHC (Major Histocompatibilty antigens) allorecognition? ...MHC I or MHC II?

MHC I & MHC II (cross-presentation); presenting alloantigens on transplanted donor organ to the recipient's T cells *Direct (Donor presents)*: *Donor's own APCs with Allo-MHC expressed on its surface*, migrates to lymph node or spleen to be *recognized by recipient T cells*. - Can be *MHC Class I or MHC Class II*. *Indirect (Recipient presents)*: *Recipient's APC endocytoses donor's Allo-MHC into an exosome and processes Allo-MHC's into proteins on their own MHCs*, which is expressed and *recognized by recipient T cell receptor*. - *Only MHC Class II* presentation as Ag presentation occurs in exosome whereas MHC I processes Ag presentation in RER. - Makes Anti-HLA-Ab's

How many organs are targeted in Organ-Specific Autoimmune Diseases? What 2 things can occur during an Organ-Specific Autoimmune Disease? Which HSR types (are Organ-Specific) cause Organ-Specific Autoimmune Disease? Why is HSR Type III not Organ-Specific?

Manifestations are usually limited to a *single* organ 1. Cells of target organ are *damaged* directly ...or... 2. Autoantibodies may *overstimulate or block* the normal function of the target organ *Due to Type II and IV HSR are organ specific* Type III is not organ specific and it is systemic because immune complexes can circulate in your blood stream and deposit in multiple spots.

For Systemic Autoimmune Diseases, what is the HSR type of RA?

Many susceptibility genes are shared among autoimmune rheumatic diseases, suggesting overlap in their pathogenesis - HSR Type III & IV.

Peripheral Tolerance What specifically causes anergy of T cells? What are the the 2 general forms of T reg cells produce (includes central as well as periphery)? ...what is the expression of central nTreg cells? ...what are the 2 iTreg cell types produced in periphery? ...what are the cytokines that induce their expression and which has Foxp3?

Mechanisms of Peripheral Tolerance: 1. *Inactivated (anergy)* - *Signal 1 without signal 2*: TCR-MHC (signal 1) but no CD28-B7; no co-stimulator. 2. *Suppressed by regulatory T cells (Tregs)* - 2a. Central nTreg Formation: CD4+ T cells expressing Foxp3 leave the thymus as "natural" regulatory T cells (nTreg). *CD4+,CD25+,Foxp3+ T cells*. - 2b. Peripheral iTreg Formation: Antigen challenge of CD4+, Foxp3- T cells in the periphery can result in *"induced"/adaptive T reg cells* (iTreg), *Tr1 (via IL-10)* or *TR (via TGF-β)*...or T effector cells (TE). = 2ba. Tr1: favoured by IL-10 = 2bb. TR (Foxp3+ TR): favored by TGF-β which upregulates Foxp3 3. *Kept immunologically ignorant*

ATOPIC URTICARIA (HIVES) = ACUTE ...what mediates atopic urticaria (hives) and where do allergens enter? ...what are typical allergens of atopic urticaria (hives)? ...what are symptoms of allergen exposure? ...what is the treatment of this disease and how does this reduce the duration of atopic urticaria (hives)? Why does this treatment work?

Mediator & Route of Entry: Atopic urticaria (hives) is mediated by an *IgE RESPONSE TO ALLERGENS* that *enter through the skin (subcutaneous???) from outside or inside (via circulation)*. Typical allergens: components of *insect venoms, drugs, or food allergens*. Symptoms of Atopic Urticaria (Hives): Allergen exposure results in itchy raised *welts (aka wheal & flare) within minutes or hours* of ingestion or exposure. Lesions have a raised edge, but upon resolution, usually leave no trace. Duration when treated: These reactions can *subside within hours* upon administration of *antihistamines or steroids*. - Antihistamines block histamine action of vasodilation and steroids block the inflammatory response in general (immunosuppressive therapy).

What are the 3 methods used for Autoimmune Type II & III HSR Disease Treatment?

Method 1: *Plasmapheresis* - Removal of autoAbs by using a machine which has a membrane which filters out Ab's while blood freely returns to the patient Method 2: *Intravenous immunoglobulins (high dose)* Method 3: *Bind to negative co-receptor on B cells* (ITIMs???) *and suppresses antibody (including autoantibody) production.* Personally think best combination would be 1 first, 3 second, and 2 third.

In Sensitization Phase of HSR I, what primary reason explains why we have too much Th2 vs Th1?

More Th2 than Th1 (Th1 = good healthy response) - Hygiene Hypothesis: Babies have Th2 predominant immune system (not able to produce IgG until later) BUT exposure to antigens (infections, microbes, animals, etc.) facilitates change to a Th1 response. - If this exposure doesn't occur (due to squeaky clean hygiene), they continue to give an inappropriate Th2 response.

Sjogren's Syndrome What is the HSR type? Why? Be specific. What are the clinical features? What is used & found to make a diagnosis?

Most likely HSR IV as *autoimmune destruction of exocrine glands (Type IV?)* - Predominantly *lacrimal & salivary glands* 90% women; onset >40 years Second most common rheumatic disease (behind SLE) Can occur with other rheumatic diseases (RA, SLE) Clinical Features: Inflamed glands lead to... - *Dry eyes* - decreased production of tears, red eyes - *Dry mouth* - decreased production of saliva - *Skin rash* Diagnosis: - *Shrimer's Test* (tear production) - Spit Test - Autoantibodies = *ANA (anti-Ro, -La)* and *RF* - Biopsy of enlarged gland Treatment: - Fluid replacement (artificial tears; lozenges; mouth wash) Immunosuppressive drugs

Multiple Myeloma What is the Defect of Multiple Myeloma? What are the 2 main symptoms of Multiple Myeloma? What is the general diagnosis of Multiple Myeloma? ...protein type in excess? ...damaged organs? What is MGUS? What cytokine mediates Multiple Myeloma? What mediates bone destruction? What would serum protein electrophoresis show?

Multiple Myeloma *IgG* Defect: *Hyper-proliferation and survival of myeloma cells (IgG goes crazy w/ proliferation)* S/S: fatigue, *bone pain (lower back), renal failure (not in Waldenstrom's Macroglobulinemia)*, recurrent infections. Dx: at least 10% of *Plasma Cells in marrow* - *Monoclonal protein in serum/ urine (Bence Jones proteins/ PARAPROTEIN/M-PROTEINS - excess light chains - contribute to renal failure)* - Usually proteins of gamma-chain class - *End-organ damage (kidney, bone, hypercalcemic anemia)* - *MGUS* (Monoclonal gammopathy of undetermined significance) *= initial Dx if PC has not reached 10% level yet* = Can progress to become Multiple Myeloma once as it surpasses threshold Pathology: - *Proliferation and survival* of myeloma depends on *IL-6* - *Bone destruction* is mediated by *MIP-1α and RANKL* (the receptor activator of NF-кB) which *activate osteoclasts*. - Final phase ~agammaglobulinemia with increased susceptibility to encapsulated infections (missing IgG!) Serum protein electropheresis - Normal - very widespread - Polyclonal- protracted, *excessive B cell stimulation* = eg. endocarditis: *wide spread* - *Monoclonal* - clonal proliferation - almost always a plasma cell = *Spike - narrow = only 1 isotype.* = Immunofixation electrophoresis - IFE - Electrophoresis of serum from a patient with Multiple Myeloma = Normal Serum (Serum albumin): Has both kappa and gamma; both types = Multiple Myeloma Serum: *Since clonal...either all are kappa or gamma*; not both but just one.

NBT - Diagnostic testing algorithm for primary immunodeficiency disease What are the 4 ways NBT test is applied? What type of testing is this?

NBT test: 1. Hemolytic complement 2. Nitroblue tetrazolium test 3. Sweat chloride test. 4. Mucosal cilia biopsy Genetic/molecular testing

What are the 3 ways in which tolerance is defective, allowing autoimmunity to occur? What causes a defect in central tolerance? What sites would a release of sequestered ("untolerized") antigens would be a problem? Be specific on the areas.

No "Tolerances": *Failure to delete or functionally inactivate self-reactive lymphocytes*. 1. Defect in Central Tolerance: *AIRE defect* 2. *Treg (CD4+25+Foxp3+) deficiency or malfunction*. 3. Release of sequestered antigens: *that were not previously accessible to the immune system* = *Have not been tolerized against these antigens* = *Immunoprivileged sites: eyes, brain, testes, uterus* = ex: eye trauma to one eye elicits damage to other

What happens to a developing T cell during negative selection if... ...it binds AIRE/MHC with high affinity? ...medium affinity? ...low affinity? (In peripheral tolerance) What happens if it binds with high affinity in periphery?

Passed positive selection (can bind MHC), now to see to what affinity... 1. Bind w/ high affinity = autoreactive *Apoptosis* - If TCR binds *Aire-induced tissue-specific self antigens* with *high affinity*, thymocyte dies by apoptosis. 2. *Treg formation*: Bind w/ medium affinity = 3. *CD4+ OR CD8 formation*: Bind w/ low affinity = In peripheral (not thymus)... - High affinity: between T cell's TCR and DC's MHC/self-peptide: leads to peripheral T cell tolerance by means of... 1.) T cell deletion 2.) Treg induction 3.) Anergy. - Low/Intermediate: Basically no change; results in tonic TCR signalling and maintenance of T cells responsive to foreign antigen.

What is the function of peripheral tolerance? What are the 3 primary mechanisms of peripheral tolerance?

Peripheral Tolerance: *Prevents peripheral self-reactive cells from causing pathology*. - Takes care of self-reactive T cells that central tolerance did not catch. Mechanisms of Peripheral Tolerance: 1. *Inactivated (anergy)* - Signal 1 without signal 2: TCR-MHC (signal 1) but no CD28-B7; no co-stimulator. 2. *Suppressed by regulatory T cells (Tregs)* - 2a. Central nTreg Formation: CD4+ T cells expressing Foxp3 leave the thymus as "natural" regulatory T cells (nTreg). CD4+,CD25+,Foxp3+ T cells. - 2b. Peripheral iTreg Formation: Antigen challenge of CD4+, Foxp3- T cells in the periphery can result in "induced"/adaptive T reg cells (iTreg), Tr1 (via IL-10) or TR (via TGF-β)...or T effector cells (TE). = 2ba. Tr1: favoured by IL-10 = 2bb. TR (Foxp3+ TR): favored by TGF-β which upregulates Foxp3 3. *Kept immunologically ignorant*

For XLA ...what would peripheral blood lymphocytes from male with BTK- express? ...what would peripheral blood lymphocytes from heterozygote female with BTK-/BTK+ express? Why? What do FACS show?

Peripheral blood lymphocytes from *female carriers show non-random X-chromosome inactivation.* Skewed aka "Non-Random" X-inactivation: Even though a female is heterozygous, the btk- (mutant type) is actually favored over btk+ (wild-type; normal). As a result the chance of a heterozygote female to have XLA is not 50:50 but "skewed" towards XLA...males have no chance (100%). Note FACS too *No B-cells but T-cells present* - No CD19 (On y axis. CD19 acts is a pan B Cell marker), instead migrates to CD3 (x-axis; pan T cell marker). = Src kinases phosphorylate CD19 & ITAM (Igα & Igβ) = CD19 is a positive co-receptor which acts synergistic with BCR.

How does Rhogam prevent HDNB?

Prevention of HDNB with Rhogam (IgG anti-Rh) - *Prevents sensitization: by binding all fetal RhD that passed placenta in MATERNAL BLOOD so mom can't bind to it*; prevents mother from forming her own IgG via B cell activation of memory. (C', ADCC???) = Treatment has to happen at first pregnancy, prevents sensitization; prevents IgG anti-Rh production. - Administer: 28 wks, 36 wks, at birth of first child

Humoral Immunodeficiency What are the 3 (of 6) Primary B cell Deficiencies? For Primary B Cell Deficiencies... ...what is XLA also known as? ...when does Common Variable Immunodeficiency (CVID) manifest? What is the Primary T Cell Mutation, and what is happening in this syndrome?

Primary B cell deficiency 1. *X-linked agammaglobulinemia (XLA)*, also known as Bruton's agammaglobulinemia = This was covered in block 2 2. *Selective IgA deficiency* 3. *Common variable immunodeficiency* (CVID) = MANY ID's.... = *Key = PRESENT LATER ON IN LIFE* 4. Immunoglobulin IgG subclass deficiencies 5. Transient hypogammaglobulinemia of infancy = *Lag in certain infants Ig lvls; they will eventually develop a normal non ID imm-system* Primary T cell mutation - *X-linked hyper-IgM syndrome* = *Usually a T-cell defect - but here, only affecting T-cells ability to help B cell rearrangement*; T cell has no CD40L for B cell activation for isotype switching.

What does RAST (*R*adio*A*llergo*S*orbent *T*est) test for? Be specific. What is the process of a RAST?

RAST tests for HSR Type I. - *DETECTS ALLERGEN-SPECIFIC IgE IN SERUM = + RESULT* *1.) Radio isotope attached to anti-human-IgE placed inside vial coated w/ target antigen (allergen)* *2.) Mix w/ patients serum, containing IgE* *3.) Binding of a radiolabeled anti-IgE antibody to IgE-antigen complex allows QUANTIFICATION of specific IgE in the serum.* *- SPECIFICITY and isotope*

Review of SCID types

REVIEW SLIDE

HIV RNA is transcribed by viral reverse transcriptase into DNA that integrates into the host-cell genome.

RT enzymatic activities Complementary DNA transcribed from RNA genome RNase activity destroys RNA strand Complementary DNA from DNA template § Made as it's chewing away complimentary strand

In Sensitization phase of HSR I... ...what is the Sensitization process of HSR I? ...what is the most common allergen that induces HSR I? Does sensitization itself have symptoms? Why or why not?

SENSITIZATION: Th2 response induced by allergen to secrete *IL-4, IL-13, and TNF-a*, causing B-cell isotype switching to IgE. 1. Allergen enters mucosa, and is picked up by dentritic cells (an APC). 2. Dendritic cells carry allergen to a lymph node, and presents to Th0 3. Th0 is in contact with APC, for autocrine (IL-4 self-secreting) differentiation to Th2. 4. Activated Th2 cells continue to secrete IL-4 (and IL-13???) which stimulates B Cell (differentiation to plasma cells too???) isotype switching to IgE. 5. IgE secreted by plasma cells bind to FcεR on mast cells for their activation - IgE high affinity for Mast Cells and Basophils, low affinity for Eosinophils Sensitization: 1st exposure w/ allergen (ex. respiratory allergen *Derp1*) - Another mentioned allergen: fecal pellets of dust mite *Mast cell degranulation w/ Derp1 ON RE-EXPOSURE; NO SYMPTOMS OF ALLERGY UNTIL SUBSEQUENT EXPOSURE (elicitation)*

Secondary Immunodeficiencies How are they derived? What are 3 causes of Secondary Immunodeficiencies?

Secondary Immunodeficiencies = *ACQUIRED* - *tend to be later in life* - *some are transient due to viral infections* - Secondary immunodeficiencies are major predisposing causes of infection and death. Causes - Virus Infections = Acquired immunodeficiency - HIV/AIDS - Malignancies of the B cell system Malnutrition, burns - Physiological stress - Aging - immuno senescence - Drugs, *chemotherapy, immunosuppressants* - Radiotherapy

Allergen inhalation is associated with development which 2 Type I Respiratory Diseases? What is the process of sensitization of an inhaled allergen? In process of sensitization... ...which APC's process extracted allergens for MHC II presentation? ...where exactly do these APC's present processed allergens to Th2?

Sensitization to an inhaled allergen is associated with development of *RHINITIS aka HAY FEVER* (large allergen lodges upper respiratory) and *ASTHMA* (small allergen lodges further into lower respiratory). Sensitization to an inhaled allergen process? Step 1: *ALLERGEN EXPOSURE* (eg pollen). Step 2: *EXTRACTION OF ALLERGEN TO APC* - Large allergens lodge in upper airway tissue, inducing rhinitis aka hay fever - Small allergens lodge in lower airway tissue, inducing asthma Step 3: APC's *MHC II PRESENTATION* for antigen-specific CD4 *Th2 ACTIVATION*. - Extracted allergen is processed by APC's (*ALVEOLAR MACROPHAGE, EOSINOPHILS, and PLASMACYTOID DENDRITIC CELLS*) and carried to the TH2 cells within *BRONCHOPULMONARY LYMPH NODES*. Step 4: *PRODUCTION OF IgE & BINDING TO MAST CELLS* - Th2 secrete cytokines IL-4, and IL-13 for B cell isotype switching to IgE, which then binds to FcεR of mast cells.

Between extrinsic asthma, and intrinsic asthma... ...what are the similarities? ...what is the difference/characteristic of extrinsic asthma? EXTRA: ...what is the difference/characteristic of intrinsic asthma?

Similarities - Inflammatory disease of lung airways: 1. *intermittent airway narrowing* 2. and variable symptoms 2a. *chest tightness* 2b. *wheeze* 2c. *shortness of breath* Differences: *Extrinsic Asthma (this is the one we are focusing on)* - HSR Type I: (atopic) - *MOST COMMON TYPE* - Childhood and young adults; *FAMILY HISTORY* - Common *ALLERGENS*: pollen, dust, food, molds, animal dander, house dust mite fecal material, etc. - Occupational allergens: fumes, gases, and chemicals Differences: Intrinsic Asthma - Unknown mechanism (NOT a HSR Type I) - Caused by respiratory infections (usually viral). = Also caused/exacerbated by Stress, Exercise, Cold temperatures, Drug induced (aspirin)

What is an example of a disease that involves release of sequestered antigens that were not previously accessible to the immune system? What is the process of Sympathetic Opthalmia? What is the typical case presentation for Sympathetic Opthalmia?

Sympathetic Ophthalmia: example of *trauma-induced autoimmunity* 1. Damage one eye...release sequestered antigens from that eye. 2. These antigens return to LN's....T-cells see these previously hidden Ag's and become activated against them. 3. *Effector T cells return via bloodstream and attack antigen* in *both eyes* (HSR Type IV) Typical case presentation: Loss of vision in one eye due to trauma and then *later in both eyes*; other eye that had no trauma also loses vision.

What are the 5 Systemic Autoimmune Diseases?

Systemic Lupus Erythematosus (SLE) Rheumatoid Arthritis (RA) Scleroderma Sjogren's Syndrome Wegener's Granulomatosis

What are examples of 1 Systemic and 3 Local Reactions in HSR Type I?

Systemic Reaction: 1. *ANAPHYLAXIS* Local Reaction: 1. *ASTHMA* 2. Food Allergy 3. Hay Fever (*RHINITIS*) 4. Skin "rash" (Urticara); *ECZEMA*

Organ-Specific Autoimmune Disease - Type IV What are the 7 Type IV Organ-Specific Autoimmune Diseases? Include their targets.

T cell mediated destruction - Antibodies are Diagnostic: produced secondary to destruction 1. Type I Diabetes Target: Pancreas 2. Hashimoto's Thyroiditis Target: Thyroid Gland 3. Addison's Disease Target: Adrenal Cortex 4. Pernicious Anemia Target: Gastric parietal cells 5. Multiple Sclerosis Target: Nervous system 6. Inflammatory Bowel Diseases Target: GI tract 7. Celiac Disease Target: GI tract

What is transplantation? What is transfusion?

Transplantation: Transfer of living cells, tissues, and organs (a graft) from one part of the body to another or from one individual (donor) to another (recipient or host). Transfusion: Grafting blood cells. Special case of transplantation and the most frequent. Graft - donated tissue Donor - person who provides the graft Recipient - person who receives the graft Transfusion - grafting blood cells Rejection - specific immunological eradication of a graft

What is 1 of the 5 Treatment Strategies against HSR Type I?

Treatment Strategies 1. Allergen avoidance - Easier said than done 2. Correct Th1/Th2 imbalance - Not clinically feasible yet 3. Block mediators - Antihistamines, leukotriene inhibition, corticosteroid inhibition of NF-kappaB *4. Correct isotype switch to IgG* *- desensitization* 5. Prevent IgE mediated degranulation

What are the 4 forms of Graft Rejection? What are is the time & cause of Hyperacute, Accelerated, Acute, and Chronic forms of graft rejection? What are the 3 ways to get pre-formed Ab's?

Type 1. Hyperacute: Mismatched ABO blood groups which react w/ endothelium and results in hypoxic death of graft - Time: *minutes-hours* - Cause: *Pre-formed anti-donor antibodies + complement* = 3 ways to get pre-formed Ab's: Pregnancy, blood transfusion, previous transplantation. 2. Accelerated (*memory*; like elicitation???): Type IV HSR; exposure to sensitized/memory T-cells to pre-seen Ag (indirect activation - donor APC activates REC T-cell) - Time: *Days (2 - 4)* - Cause: Secondary activation of *Memory T cells* - Type IV HSR: T-cells activated and then develop more T-cells 3. Acute (*primary*; like sensitization???): - Time: *Week (>1 week)* - Cause: *Primary activation* of T cells (DC -> MHC -> T cells) - HSR Type IV: T-cells activated and then develop more T-cells 4. Chronic: - Time: *Months - years* - Cause: *Antibody- and cell- mediated rejection.* Poorly understood. - HSR Type II

For 4 types of Hypersensitivity Reactions... ...what is the primary mediator of HSR I? ...what is the 2 time frames of HSR I? ...what are examples of HSR I? ...what is the primary mediator of HSR II? ...what are examples of HSR II? ...what is the primary mediator of HSR III? ...what is an example of HSR III? ...what is the primary mediator of HSR IV? ...what is the time frame of HSR IV? ...what are examples of HSR IV?

Type I: IgE mediate - *Immediate - minutes* = ex: Allergies, allergic asthma, systemic anaphylaxis (*ALL soluble Ag's*) - Late response - hours Type II: Ab mediated to cell surface Ag's - ex: penicillin, IgG FcyR mast cells (*cell surface Ag's*) Type III: *IMMUNE COMPLEX (WITH Ab's)* mediated via *soluble Ag's* - ex: serum sickness Type IV: T-cell mediated - *Delayed - days* - ex: contact dermatitis (poison ivy, nickel, latex)

Goodpasture's Syndrome ...what is the HSR type? ...what generally happens? ...how would you diagnose this on a histology slide?

Type II HSR Autoantibodies made against *α3 chain of type IV collagen* in glomerular *basement membrane* (kidney) & *alveolar basement membrane (lung)* - Histology Slide:*"linear"* (anti-IV collagen) *IgG deposition along capillary loops* seen; IgG traveled from these capillary loops to kidney & lungs. Phagocyte/complement activation → inflammation + tissue damage One of the exceptions: Usually affects men

Graves' Disease: Hyperthyroidism ...HSR Type? ...what is the mechanism? ...what is the clinical manifestation? Be specific. How can you diagnose of Grave's Disease?

Type II HSR Mechanism of Graves' Disease: - Normal: Pituitary secretes TSH that bind TSH-R *on thyroid cells*, which triggers release of thyroid hormones (T3,T4). *This stops TSH production* & thyroid hormone production. - Graves' Disease; Hyperthyroidism: Anti-TSH-R autoAbs* bind to and *activate* (agonistic) *thyroid-stimulating hormone receptor (TSH-R)* on thyroid cells, leading to *overproduction of T3/T4* (which increases negative feedback lowering TSH levels). Clinicals: Enlarged thyroid gland (*goiter*) - Too much metabolism: heat intolerance, irritability, nervousness, warm moist skin, weight loss - *Exophthalmos* Diagnosis: *High T3/T4 levels in patient plasma, with no TSH* Treatment: - Anti-thyroid drugs that inhibit thyroid function - Thyroid removal or destruction by radioiodine (131I), with synthetic thyroid hormone daily EXTRA: Affects 0.5% of the population Cause of ~80% of hyperthyroidism Female to male 7-10:1 Peak is 40-60 years old

Non-Cytotoxic/Cytolytic Type II HSR - Myesthenia Gravis What is the cause of Myasthenia Gravis? What is the general clinical manifestation of Myasthenia Gravis? ...of facial muscles? ...of chest muscles? What is the treatment of Myasthenia Gravis? What occurs during Lambert-Eaton Syndrome? ...what is the clinical manifestation?

Type II HSR Myasthenia Gravis Mechanism: Post-synaptic block of AChR. - Normal: Stimulated motor neurons secrete ACh and binds to AchR (M2) on muscle cells for contraction. - Abnormal; Myasthenia Gravis: AutoAbs against ACh at *post-synapse block AchR binding* by ACh, resulting in muscle cells to become less responsive to ACh. Clinical Manifestation: *Progressive weakening of muscles* for *poor muscle contraction*. - Facial muscles: drooping eyelids *(ptosis)*, tongue, mouth - Chest muscles: *impaired breathing*, respiratory infections Diagnosis of Myasthenia Gravis: Anti-AchR antibodies in serum Treatment of Myasthenia Gravis: - *Acetylcholinesterase inhibitor*: increase acetylcholine levels by preventing breakdown of released acetylcholine Lambert-Eaton Syndrome: Presynaptic block of V-gated Ca2+. - Mechanism: AutoAbs against (*presynaptic*) voltage-gated Ca2+-channel on neuron *block release* of ACh. - Clinical Manifestation: *Poor muscle contraction*

What are the 3 HSR Type II HSR CYTOTOXIC Diseases? What occurs during HDNB, and what is the preventative treatment? What occurs during Transfusion/Transplantation reaction, and what specific Ig is involved? What diseases involve Ab's that respond to self, causing tissue damage? What are the 4 HSR Type II HSR NON-CYTOTOXIC Diseases? Explain each.

Type II HSR CYTOTOXIC Diseases 1. Autoimmune Hemolytic Anemia (HDNB): maternal anti-Rh Ab's cross placenta & attack Rh+ fetus RBC's; Damage baby - 1st Rh+ baby is fine = sensitization - *Rhogam (IgG anti-Rh)*: Preventative treatment. Binds ITIM; FcγR=inhibitory. Bind up baby's Rh+ RBCs that went in mother; *therefore no sensitization*. 2. Transfusion/Transplantation reaction: ABO blood type not matched; damage donor - *IgM* 3. Ab's in response to self cause tissue damage: Damage self - Goodpasture Syndrome: *Anti-collagen IV*; BM; *smooth linear deposition pattern* - Rheumatic fever: *Myocarditis*. Group A strep cross reaction; molecular mimicry. = Do not confuse with Rheumatoid Arthritis, a HSR type III. - Penicillin rxn: Modifies cell membrane proteins into foreign epitopes - Thrombocytopenic Purpura: *Ab's against platelets* Type II HSR NON-CYTOTOXIC Disease 1. Myasthenia Gravis: *Blocks AChR* 2. Grave's Disease: *Stimulates TSH-R* - activates Thyroid Hormone production 3. Type II Diabetes: *Ab to insulin R* blocking it = hyperglycemia 4. Pernicious anemia: *Ab's to IF of parietal - low B12. Initiated by a Type IV HSR*

Type 1 Diabetes (Insulin-Dependent Diabetes Mellitus; IDDM) Which HSR Type is Type 1 Diabetes? What is the cause of Type 1 Diabetes? What is the clinical manifestation? What is the mechanism? How would you diagnose Type 1 Diabetes? What is important to note about the Ab's produced in an HSR Type IV like Type 1 Diabetes?

Type IV HSR - Delayed Cell Mediated Cause: *Specific destruction* of *insulin-producing β-cells* in pancreatic islets by *autoreactive T cells* - β-cell autoantigen targeted is unknown (glutamic acid decarboxylase 65 [GAD65] via molecular mimicry???) Clinical Manifestation: Decreased insulin production → *hyperglycemia* DTH (Type IV) and autoantibodies (C', ADCC; Type II???) Mechanism: Delayed Type Hypersensitivity 1. *Cross-reactivity* (Cross-linking as it should be haptenated self-protein): Similar peptides (molecular mimicry???) between (infecting???) *Coxsackie Virus* and islet cell autoantigens glutamic acid decarboxylase 65 (*GAD65*). - Hapten (haptenated self-protein)??? - Sensitization Phase (Langerhans in mucosa; MHC II; Th1/CTL as effector memory cells)??? 2. *β-cell-specific Th1 cells make IFNγ*; Effector Phase - Pathway 2 - MHC II-Th1: Cytokines released by Th1 recruit monocytes while IFN-γ activates *Macrophage activation (TNF-α and IL-1)* to secrete lytic enzymes (hydrolases, oxidases), causing cell & tissue damage. 3. MHC I-CTL: β-cell-specific CTL (perforin & granzymes) Insulitis Diagnosis: *Autoantibodies against GAD65 & insulin diagnostic* - High blood glucose *Ab's are NOT pathogenic...they are diagnostic*

For Bone Marrow Transplantation; Hematopoietic Cell Infusion... ...what 2 things does it treat? ...what 2 challenges must it overcome? What is are the 4 factors for a conditioning regimen?

Used to treat: 1. Hematopoetic, immune system and other deficiencies 2. Certain malignancies Several challenges: - Must ablate mutated bone marrow in recipient for donor transplant. - Graft vs. Host Disease (GVHD): Grafted tissue may mount an immune response to host tissue. *Conditioning regimen*: These 4 factors must be implemented before hematopoietic cell infusion. 1. *Radiation*. 2. *Chemotherapy*. 3. *Immunosuppressants*. 4. *Antivirals*. Bone marrow could have alloreactive T cells that lead to rejection. And also need to do the conditioning regimen in order for the patient to accumulate to the BMT.

What type of immunosuppression do viruses cause in general? What does EBV do? What do measles do? What does CMV do?

Viruses are tricky and can hijack or inhibit critical immune functions *Transient immunosuppression* EBV- binds to the *IL-10 receptor on B* cells and can also prompt the B cell to make IL-10 which *suppresses CD8 anti-viral reactions* Measles- inhibits production of IL-12 and *prevents a Th1 response* CMV and many other viruses can *inhibit antigen processing* pathways and prevent presentation of viral antigens

Waldenstrom's Macroglobulinemia: What is the defect? What are the 3 main symptoms? ...why do 2 of these symptoms occur? During a diagnosis, what would you not see? What would you see and how is that treated? What is the mean survival rate?

Waldenstrom's Macroglobulinemia: IgM Monoclonal Gammopathy Defect: *Hyper-proliferation and survival of myeloma cells (IgM goes crazy w/ proliferation)* S/S: MALES 60-70 fatigue, w/ fever, anemia, *splenomegaly*, fatigue, recurrent infections. - PREDISPOSED TO *visual and neurologic disturbances* = Due to *hyper-viscosity impairing blood flow* Dx: *NO End-organ damage* (kidney, bone) - *Hyper-viscosity* of plasma d/t increased volume = Treated w/ *plasmapheresis* (remove IgM and make less viscous) - B.M. inflatrated w/ plasmacytic lymphocytes (differentiates it from MGUS) Tx: Autologous stem cell transplant Pathology: - *Mean survival is 4-6 years*

X-linked SCID ...what is characteristic of this disease? ...what is the cause/deficiency? (HINT: Keep it simple to 1 IL.) ...what do labs show for a diagnosis? ...what are the symptoms? Be particularly specific for 1 of the symptoms. ...who died form this form of X-SCID?

X-linked SCID (most common SCID) Deficiency: *γ-chain of the IL-2 receptor (This γc chain is also a component of the IL-4, IL-7, IL-9, IL-15 and IL-21 receptors.)* - No IL-2Rγ on surface of B cells (its IL-7R is compensated for VDJ recombination), but is necessary to activate T cells. Defect: *SCID* (meaning???) MoI: X-linked Dx: T-, *B+*, NK- (why we still get B cells is explained 2 slides from now)* S/S: Similar to XLA but differs by additional features of...: - Lymphocytopenia - *Death at earlier age* - LACK of DTH - *ATROPHY of THYMUS* - *Lack of benefit from IV-gamma-globulin administration (no T cells to mediate responses)* (???) Non-random inactivation of X chromosome in mother's T cells The bubble boy died from X-SCID