Lymphatic & Immune System Combined
How do antigen-presenting cells help specific immunity?
- T cells are incapable of recognizing antigens on their own so they rely on antigen presenting cells such as dendritic cells, macrophages, reticular cells, and B cells
Where do T-cells achieve immunocompetence?
- T cells leave the bone marrow and enter into the blood stream where they travel to the thymic cortex - Reticular epithelial (RE) cells secrete hormones that stimulate T cells to develop surface antigen receptors -- making them immunocompetent; capable of recognizing antigens presented to them by APCs
What are the three different types of lymphocytes?
1) NK cells 2) T cells 3) B cells
What are the five types of leukocytes? 'Never Let Monkeys Eat Bananas'
1) Neutrophils 2) Eosinophils 3) Basophils 4) Lymphocytes 5) Monocytes
Place the following statements into the correct order to represent the sequence of events associated with the action of antigen-presenting cells. Phagocytosis of antigen Processed antigen fragments (epitopes) are displayed on the macrophage surface Lysosome fuses with phagosome Antigen is degraded Antigen and enzyme mix in phagolysosome
1) Phagocytosis of antigen 2) Lysosome fuses with phagosome 3) Antigen and enzyme mix in phagolysosome 4) Antigen is degraded 5) Processed antigen fragments (epitopes) are displayed on the macrophage surface
B cell internalizes antigen and displays processed epitope. Helper T cell binds to B cell and secretes interleukin.
2) Antigen Presentation
Interleukin stimulates B cell to divide repeatedly and form a clone.
3) Clonal Selection
Some cells of the clone become memory B cells. Most differentiate into plasma cells.
4) Differentiation
Plasma cells synthesize and secrete antibody. Antibody employs various means to render antigen harmless.
5) Attack
*Chemical Agent* Bradykinin
A kinin that stimulates vasodilation and capillary permeability; stimulates pain receptors and is a neutrophil chemotactic factor
What is inflammation?
A local defensive response to tissue injury of any kind, including trauma and infection General purposes are: 1) limit spread of pathogens and ultimately destroy them 2) remove debris of damaged tissue 3) initiate tissue repair
What is metastasis?
A phenomenon in which cancerous cells break free of the original primary tumor, travel to other sites of the body, and establish new tumors
What is immune surveillance?
A phenomenon in which natural killer (NK) cells continually patrol the body on the look out for pathogens
*Chemical Agent* Fibrinogen
A plasma clotting protein that filters into inflamed tissues and forms fibrin, thus coagulating tissue fluid, sequestering pathogens, and forming a temporary scaffold for tissue rebuilding
*Chemical Agent* Heparin
A polysaccharide secreted by basophils and mast cells that inhibits clotting of tissue fluid within the area walled off by fibrin, thus promoting free mobility of leukocytes that attack infectious microorganisms
*Chemical Agent* Histamine
An amino acid derivative produced by basophils and mast cells that stimulates vasodilation and capillary permeability
*Chemical Agent* Chemotactic factors
Chemicals that provide a trail that neutrophils and other leukocytes can follow to specific sites of infection and tissue injury; include bradykinin, leukotrienes, and some complement proteins
*Cellular Agent* Macrophages
Clean up tissue damage; phagocytize bacteria, tissue debris, dead and dying leukocytes and pathogens
Describe lymph.
Clear, colorless fluid *similar to blood plasma* but low in proteins. It's composition varies throughout the lymphatic system. After meal may contain high concentrations of lipids due to absorption from small intestinal lacteals. After leaving lymph nodes, contains a higher number of lymphocytes.
*Chemical Agent* Selectins
Cell-adhesion molecules of endothelial cells that adhere to circulating leukocytes, promoting margination and diapedesis
How do basophils and mast cells perform their functions?
FUNCTION: Secrete chemicals that aid in the mobility and action of other leukocytes BY WAY OF: *Leukotrienes:* activate and attract neutrophils & eosinophils *Histamine:* increases blood flow and speeds the delivery of leukocytes to the area *Heparin:* inhibits the formation of blood clots that would impede leukocytes mobility
What is the structure of a lymph node?
Each lymph node is surrounded by a *fibrous capsule*, and inside the lymph node the fibrous capsule extends to form *trabeculae*. The substance of the lymph node is divided into the *outer cortex and the inner medulla*. *cortex* - consists mainly of the B cells arranged as follicles, which may develop a germinal center when challenged with an antigen, and the *deeper cortex consists mainly of the T cells* *medulla* - contains large blood vessels, sinuses and medullary cords that contain antibody-secreting plasma cells. - Lymph flows into the medullary sinuses from cortical sinuses, and into efferent lymphatic vessels. Medullary sinuses contain histiocytes (immobile macrophages) and reticular cells.
*Chemical Agent* Prostaglandins
Eicosanoids that stimulate pain, fever, and vasodilation; promote neutrophil diapedesis; enhance histamine and bradykinin action
*Chemical Agent* Leukotrienes
Eicosanoids that stimulate vasodilation, capillary permeability, and neutrophil chemotaxis, especially in inflammation and allergy
*Cellular Agent* Monocytes
Emigrate into inflamed tissue and become macrophages
*TRUE or FALSE* Anergy is often a cause of autoimmune diseases.
FALSE; *Anergy is a loss of lymphocyte activity*, whereas autoimmune diseases results from misdirected activity
*TRUE or FALSE* Interferons help to reduce inflammation
FALSE; Interferons *promote* inflammation
*TRUE or FALSE* Interferons kill pathogenic bacteria by making holes in their cell walls.
FALSE; Interferons inhibit viral replication; Perforins lyse bacteria
*TRUE or FALSE* Some bacteria employ lysozyme to liquefy the tissue gel and make it easier for them to get around
FALSE; Lysozyme is a bacteria-killing enzyme
*TRUE or FALSE* T lymphocytes are involved only in cell-mediated immunity
FASLE; Helper T cells are also necessary to humoral immunity
What is an autoimmune disease?
Failures of self-tolerance -- the immune system fails to distinguish self-antigens from foreign ones and produce *autoantibodies* that attack one's own body tissues
MHC II proteins are present on all nucleated cells in the body True or False
False; MHC II proteins are present only on APCs
What does the spleen do?
Filters blood and breaks down RBCs
Give an example of natural active immunity
Get sick; i.e. catch the measles
What do histamine and other inflammatory chemicals trigger?
Glandular secretion, vasodilation, increased capillary permeability, smooth muscle spasms, and other effects
What type of immunity does acquired immunodeficiency syndrome affect?
HIV strikes at the central coordinating agent of *nonspecific defense, humoral immunity, and cellular immunity*
How do eosinophils kill?
Help to kill parasites such as tapeworms and roundworms by producing superoxide, hydrogen peroxide, and various toxic proteins including a neurotoxin.
In order for B cells to respond to most antigens, they must be activated by what other type of lymphocytes?
Helper T cells
What secretion from basophils and mast cells causes vasodilation?
Histamine
*Chemical Agent* Colony-stimulating factors
Hormones that raise the WBC count by stimulating leukopoiesis
Which antibodies are involved in type III hypersensitivity?
IgG or IgM antibodies form Ag-Ab complexes that precipitate beneath the endothelium of the blood vessels or in other tissues
Are intra or extra cellular pathogens involved in cell-mediated immunity? Why?
It is the means of *ridding the body of pathogens that reside inside human cells, where they are inaccessible to antibodies* - Intracellular viruses, bacteria, yeasts, and protozoans - Also acts against parasitic worms, cancer cells, and cells of transplanted tissues and organs.
What is the function of lipid absorption in the lymphatic system?
Lacteals absorb dietary lipids that are not absorbed by the blood capillaries
What are the cells involved in mobilization of defenses?
Leukocytes - specifically neutrophils - Leukocyte deployment consists of margination and diapedesis - *Margination: selectins cause leukocytes (NEUTROPHILS) to adhere to blood vessel walls* - *Diapedesis (emigration):* leukocytes (NEUTROPHILS) squeeze between endothelial cells into tissue space
Which cells produce interferons?
Leukocytes that are infected by viruses
STEP 2
Lysosome fuses with phagosome
Identify the components found in lymph.
May contain macrophages, hormones, bacteria, viruses, cellular debris, or even traveling cancer cells.
How are B-cells tested?
RE cells test them by presenting self-antigens to them *Two ways to fail the test:* 1) Inability to recognize the RE cells at all, specifically their MHC proteins. *meaning* they would be incapable of recognizing a foreign attack on the body 2) Reacting to the self-antigens. *meaning* the T cells would attack one's own tissues.
How are T-cells tested?
RE cells test them by presenting self-antigens to them *Two ways to fail the test:* 1) Inability to recognize the RE cells at all, specifically their MHC proteins. *meaning* they would be incapable of recognizing a foreign attack on the body 2) Reacting to the self-antigens. *meaning* the T cells would attack one's own tissues.
*Cellular Agent* Fibroblasts
Rebuild damaged tissue by secreting collagen, ground substance, and other tissue components
*Cellular Agent* Mast cells
Same action as basophils
What are the functions of the basophils and mast cells?
Secrete chemicals that aid in the mobility and action of other leukocytes
*Cellular Agent* Helper T-cells
Secrete chemotactic factors and colony-stimulating factors
*Cellular Agent* Platelets
Secrete clotting factors and platelet-derives growth factor
*Cellular Agent* Basophils
Secrete histamine, heparin, leukotrienes, and kinins
*Chemical Agent* Cytokines
Small proteins produced mainly by WBCs; have autocrine, paracrine, and endocrine roles in cellular communication; act especially in inflammation and immune responses;
Where are complement proteins produced?
Synthesized in the *liver* and circulate in the blood stream in inactive form and activated in the presence of pathogens
Which cells initiate costimulation and what is it?
T cell binding to TWO APCs to ensure that the immune system does not launch an attack in the absence of the enemy
What do natural killer cells kill?
They attack and destroy bacteria, cells of transplanted organs and tissues, cells infected with viruses, and cancer cells
Endothelial cells display selectins which bind the integrins of neutrophils. True or False
True
Neutrophils and eosinophils secrete the same chemicals True or False?
True
The primary function of the larynx is to keep food and water out of the airway True or False
True
Which forces aid in the flow of lymph and how do they work?
Under normal conditions, lymphatic vessels are low-pressure conduits and the same mechanism that promotes venous return in blood vessels acts here as well: - *Skeletal muscle pump* - *Arterial pulsation* - *Thoracic (respiratory) pump* - *Rapidly flowing bloodstream* draws lymph into it upon return to subclavian vein.
What is a pathogen?
Viruses, bacteria, fungi, and other microbes that cause disease
What is lymphadenitis?
When a lymph is under challenge by an antigen it becomes swollen and painful to touch
Part of an antibody called the __________ binds to part of an antigen called the __________.
antigen binding site, epitope
Any disease in which antibodies attack one's own tissues is called a/an __________ disease.
autoimmune
__________ become antigenic by binding to larger host molecules a. Epitopes b. Haptens c. Interleukins d. Pyorgens e. Cell-adhesion molecules
b. Haptens
The only lymphatic organ with both efferent and afferent lymphatic vessels is a. the spleen b. a lymph node c. a tonsil d. a Peyer patch e. the thymus
b. a lymph node
Which of the following cells are involved in nonspecific resistance but not in specific defense? a. helper T cells b. cytotoxic T cells c. natural killer cells d. B cells e. plasma cells
c. natural killer cells
Which of the following results from a lack of self-tolerance? a. SCID b. AIDS c. systemic lupus erythrematosus d. anaphylaxis e. asthma
c. systemic lupus erythrematosus
Self-tolerance results from a process called __________, in which lymphocytes programmed to react against self-antigens die
clonal deletion
Which of the following is involved in humoral immunity? a) T cytotoxic b) T memory c) T regulatory d) B cells
d) B cells
The cardinal signs of inflammation include all of the following *except*? a. redness b. swelling c. heat d. fever e. pain
d. fever
The cytolytic action of the complement system is most similar to the action of a. interleukin-1 b. platelet-derived growth factor c. granzymes d. perforin e. IgE
d. perforin
The movement of leukocytes through a capillary or venule wall is called __________.
diapedesis (emigration)
Which of the following correctly states the order of events in humoral immunity? *Let 1 = antigen display, 2 = antibody secretion, 3 = secretion of interleukin, 4 = clonal selection, and 5 =endocytosis of an antigen* a. 3-4-1-5-2 b. 5-3-1-2-4 c. 3-5-1-4-2 d. 5-3-1-4-2 e. 5-1-3-4-2
e. 5-1-3-4-2
The chemical signals produced by leukocytes to stimulate other leukocytes are called __________.
interleukins
__________ is a condition in which one or more lymph nodes are swollen and painful to touch.
lymphadenitis
Mucous membranes contain an antibacterial enzyme called __________.
lysozyme
In the process of __________, complement proteins coat bacteria and serve as binding sites for phagocytes.
opsonization
Any organism or substance capable of causing disease is called a/an __________.
pathogen
Any substance that triggers a fever is called a/an __________.
pyrogen
What is the difference between active and passive immunity?
*Active Immunity* - Body makes its own antibodies or T cells against a pathogen - Immunity involves memory so provides future protection *Passive Immunity* - Body acquires the antibody for a pathogen from another person or animal that has developed immunity to the pathogen - Immunity only lasts for 2 to 3 weeks, until acquired antibody is degraded
What is type I hypersensitivity?
*Acute* - *Triggered by an innocuous foreign substance (like dust, pollen or animal dander) that would cause no problems in the majority of people* - Most common allergies - Some examples are food allergies and asthma - Clinical signs: local edema, mucus hypersecretion and congestion, watery eyes, a runny nose, hives
What is the difference between an afferent vessel and an efferent vessel?
*Afferent vessel* - deliver lymph to the lymph node to get filtered - found only in lymph nodes *Efferent vessel* - emerge from the hilum of the lymph node and take away filtered lymph that is high in lymphocytes - also found in the thymus and spleen
What is type II hypersensitivity?
*Antibody-dependent cytotoxic* - *the antibodies produced by the immune response bind to antigens on the patient's own cell surfaces* - Macrophages phagocytize and destroy opsonized platelets, erythrocytes, or other cells - Examples include blood transfusion reactions, pemphigus vulgaris, and some drug reactions - In some cases antigens bind to cell surface receptors and either interferes with their function (i.e. myasthenia gravis) or overstimulates the cell (i.e. toxic goiter)
List the function of the B-lymphocytes and identify which immune response they are associated with.
*B cells* - Serve as antigen presenting cells in humoral immunity - differentiate into antibody secreting plasma cells *Memory B cells* - Act as a pool of B cells that can execute a quick secondary response upon re-exposure o the same antigen that initially activated them
What is the function of the lymphocyte in specific immunity?
*B lymphocytes:* produce antibodies that recognize foreign substances (antigen) and attach themselves to them. B cells are each programmed to make one specific antibody. When a B cell comes across its triggering antigen it gives rise to many large cells known as *plasma cells*. Each plasma cell is essentially a factory for producing antibody. An antibody matches an antigen much like a key matches a lock. Whenever the antibody and antigen interlock, the antibody marks the antigen for destruction. *T lymphocytes:* T lymphocytes are cells that are programmed to recognize, respond to and remember antigens. T cells contribute to the immune defenses in two major ways 1) Some direct and regulate the immune responses. 2) Other T cells are able to destroy targeted cells on direct contact
What is the function of an interferon?
*Blood-borne antimicrobial protein* that alert neighboring cells and protect them from becoming infected by *viruses*. - activate second messenger systems of cell they bind to which induces synthesis of dozens of antiviral proteins that defend a cell by such means as breaking down viral genes or preventing viral replication - activate NK cells and macrophages - confer resistance to cancer
*Characteristic* Antigen-presenting cells
*Cellular Immunity:* B cells, macrophages, dendritic cells, nearly all cells *Humoral Immunity:* B cells
*Characteristic* Mechanisms of counteracting or destroying pathogens
*Cellular Immunity:* Cytolysis, phagocytosis, apoptosis *Humoral Immunity:* Cytolysis, phagocytosis, immune clearance, inflammation, neutralization, agglutination, preciptation
*Characteristic* Effector cells
*Cellular Immunity:* Cytotoxic T cells *Humoral Immunity:* Plasma cells (develop from B cells)
*Characteristic* Other cells involved in attack
*Cellular Immunity:* Helper T cells *Humoral Immunity:* Helper T cells
*Characteristic* Disease agents
*Cellular Immunity:* Intracellular viruses, bacteria, yeasts, and protozoans; parasitic worms; cancer cells ; transplanted tissues and organs *Humoral Immunity:* Extracellular viruses, bacteria, yeasts, and protozoans; toxins, venoms, and allergens; mismatched RBCs
*Characteristic* MHC proteins
*Cellular Immunity:* MHC I and MHC II *Humoral Immunity:* MHC II only
*Characteristic* Chemical agents of attack
*Cellular Immunity:* Perforins, granzymes, interferons, tumor necrosis factor *Humoral Immunity:* Antibodies, complement
*Characteristic* Memory
*Cellular Immunity:* T cell recall response *Humoral Immunity:* Secondary (anamnestic) response
Which regions of the body are congregations of lymph nodes found?
*Cervical lymph nodes* - neck; monitor lymph coming from head and neck *Axillary lymph nodes* - armpit; monitor lymph coming from upper limb and breast *Thoracic lymph nodes* - thoracic cavity; monitor lymph coming from mediastinum, lungs, and airway *Abdominal lymph nodes* - posterior abdominopelvic wall; monitor lymph coming from urinary and reproductive systems *Intestinal lymph nodes* - mesenteries; monitor lymph coming from digestive tract *Inguinal lymph nodes* - groin; monitor lymph coming from entire lower limb *popliteal lymph nodes* - back of knee; monitor lymph coming from leg proper
What is the role of a complement protein in inflammation?
- C3a stimulates mast cells and basophils to secrete histamine and other inflammatory chemicals - activates and attracts neutrophils and macrophages
What is the purpose of lymphatic valves and how do they work?
*Helps regulate the flow of lymph and prevents venous blood from entering the system.* - No valves in the capillaries of the system, but there are *many in the collecting vessels.* - They are more numerous near the lymph nodes and more prevalent in the lymphatic vessels of the neck and the arms than in the vessels of the legs. *How the work:* When fluid pressure in the interstitial space is greater than the pressure in the lymphatic capillaries, the valve flaps open, allowing fluid to enter the lymphatic capillary. When the pressure is greater inside the lymphatic capillary, it forces the endothelial valve flaps shut, preventing lymph from leaking back out as the pressure moves it through the vessel.
What is type III hypersensitivity?
*Immune complex* - an excess of antigen, leading to small immune complexes being formed that fix complement and are not cleared from the circulation.
Identify the location, structure, and function of IgG
*Location:* constitutes 80% of circulating antibodies in blood plasma; the predominant antibody secreted in the secondary immune response *Structure:* monomer, 2 binding sites *Function:* Significant complement-fixation activity; crosses placenta and confers temporary immunity on the fetus; includes the anti-D antibodies of the Rh blood group
Identify the location, structure, and function of IgE
*Location:* transmembrane protein of basophils and mast cells *Structure:* monomer, 2 binding sites *Function:* Stimulates basophils and mast cells to release histamine and other mediators of inflammation and allergy; important in immediate hypersensitivity reactions and in attracting eosinophils to sites of parasitic infection
Identify the location, structure, and function of IgD
*Location:* transmembrane protein of basophils and mast cells; found in small amounts in blood serum *Structure:* monomer, 2 binding sites *Function:* activation of b cells by antigens
Identify the location, structure, and function of IgA
*MONOMER* *Location:* blood plasma *Structure:* 2 binding sites *Function:* Prevents pathogens from adhering to epithelia and penetrating underlying tissues. Provides passive immunity to the newborn *DIMER* *Location:* mucus, tears, milk, saliva, and intestinal secretions *Structure:* 4 binding sites *Function:* Prevents pathogens from adhering to epithelia and penetrating underlying tissues. Provides passive immunity to the newborn
Identify the location, structure, and function of IgM
*MONOMER* *Location:* constitutes 10% of circulating antibodies in blood plasma; transmembrane protein of B cells *Structure:* 2 binding sites *Function:* antigen receptor for B cells; *PENTAMER* *Location:* constitutes 10% of circulating antibodies in blood plasma; blood plasma and lymph *Structure:* 10 binding sites *Function:* Predominant antibody secreted in the primary immune response; very strong agglutinate and complement-fixation abilities; includes anti-A and anti-B agglutinins of the ABO blood group
What is the difference between natural and artificial immunity?
*Natural* - Immunity acquired from mother while fetus *Artificial* - Immunity acquired either through contracted disease by patient or vaccination
Which vessel does the right lymphatic duct empty into?
*Right subclavian vein*
Describe the lymphatic vessel wall layers.
*Similar histology to veins:* - Tunica interna with an endothelium and valves. Simple squamous epithelium - Tunica media with elastic fibers and smooth muscle - Tunica externa (thin) - *Their walls are thinner and valves are closer together than those of veins*
List the three stages of humoral and cellular immunity.
*The three R's* 1) Recognize 2) Remember 3) React
What and where is diffuse lymphatic tissue found in the body?
*WHAT* - aggregations of lymphocytes in the connective tissues of mucous membranes and various organs. - Simplest form of lymphatic tissue = *diffuse lymphatic tissue --- more scattered rather than densely clustered* *WHERE* *- Prevalent in body passages that are open to the exterior ---> the respiratory, digestive, urinary, and reproductive tracts*
What are antigen presenting cells (APCs) and which cells act as an APC?
*a cell that displays antigen complexed with major histocompatibility complexes (MHCs) on their surfaces* - The functioning of both cytotoxic and helper T cells is dependent on APCs *Cells that act as APCs:* Professional APCs - macrophages - dendritic cells - B cells Nonprofessional APCs - fibroblasts (skin cells) - thymic epithelial cells - thyroid epithelial cells - glial cells (brain cells) - pancreatic beta cells - vascular endothelial cells
Which vessel does the thoracic duct empty into?
*left subclavian vein*
What is the difference between a wandering macrophages and a fixed macrophage? Where are each found in the body?
*wandering macrophage* - actively seek pathogens *fixed macrophage* - only phagocytize pathogens that come to them and are strategically positioned throughout the body
What is a major histocompatibility complex protein?
- *A family of genes on chromosome 6 that code for MHC proteins* -- proteins on APC surface that functionally hold on to the foreign antigen - *Structurally unique to every person except for identical twins*
Which immune cells are involved in type IV hypersensitivity?
- *APCs* in lymph nodes display antigens to helper T cells. - T cells secrete interferon and other cytokines that activate *cytotoxic T cells* and *macrophages* - Results in a mixture of nonspecific and immune responses - Beta cell destruction that causes type 1 diabetes mellitus
How is chemotaxis involved in containment of pathogens?
- *Chemotaxis:* attraction to chemicals such as bradykinin and leukotrienes that guide them to the injury site
How is fibrinogen involved in containment of pathogens?
- *Fibrinogen* filters into tissue fluid • Forms a sticky mesh that walls off microbes
How is heparin involved in containment of pathogens?
- *Heparin:* prevents clotting at site of injury • Pathogens are in a fluid pocket surrounded by clot • Attacked by antibodies, phagocytes, and other defenses
Which types of cells are involved in cell-mediated immunity?
- *Lymphocytes* that directly attack and destroy foreign cells or diseased host cells - Carried out by T cells within lymph nodes, bloodstream, and intercellular spaces
How are neutrophils involved in containment of pathogens?
- *Neutrophils:* chief enemy of bacteria, accumulate at injury site within an hour - After leaving bloodstream, they secrete cytokines that attracts macrophages and additional neutrophils - *Phagocytes:* Neutrophils and macrophages (from monocytes) Migrate to infected area
What is the purpose of vasodilation?
- *Stimulates increased permeability of blood capillaries*, allows blood cells and plasma proteins into tissue (antibodies, complement proteins, and fibrinogen), clotting sequesters bacteria and forms scaffold for tissue repair
What is natural passive immunity? Give an example
- A *temporary* immunity that results from acquiring antibodies produced by another person - The *only natural way* is for a fetus to to acquire antibodies from the mother through the placenta before birth or during breast-feeding
What is artificial passive immunity? Give an example
- A *temporary* immunity that results from the injection of an immune serum obtained from another person or from animals - *Immune serum* is used for emergency treatment of snakebites, botulism, tetanus, rabies, and other diseases
What is the cisterna chyli?
- A dilated sac at the *lower end of the thoracic duct* into which lymph from the intestinal trunk and two lumbar lymphatic trunks flow
What is severe combined immunodeficiency syndrome? Which immune cells are lacking?
- A group of disorders caused by recessive alleles that results in a scarcity or absence of both T and B cells - Highly vulnerable to opportunistic infections and must live in protective enclosures
What is acquired immunodeficiency syndrome (AIDS)?
- AIDS is an advanced stage of infection with the human immunodeficiency virus (HIV). HIV usually is spread from person to person through contact with infected sexual secretions or blood. - Acquired immunodeficiency syndrome (AIDS) - Nonhereditary disease - "Tricks" antigen presenting cells into internalizing it.
What does costimulation trigger?
- Activates the process of *clonal selection:* the T cell undergoes repeated mitosis, giving rise to a clone of identical T cells programmed against the same epitope - Some become Tc cells and others become memory T (Tm) cells
Which cells are involved in type I hypersensitivity?
- Allergens stimulate basophils and mast cells to secrete histamine and other vasoactive chemicals
*How antibodies render antigens useless* What is agglutination?
- An antibody has 2-10 binding sites; can bind to antigen molecules on two or more enemy cells at once and stick them together - Immobilizes microbes and antigen molecules and prevents them from spreading through the tissues
What is hypersensitivity?
- An excessive, harmful immune reaction to antigens FOUR KINDS OF HYPERSENSITIVITY: 1) *Type I:* acute (immediate) hypersensitivity b/c response is very rapid; antibody-mediated response 2) *Types II & III:* subacute b/c they exhibit a slower onset (1-3hrs after exposure) and last longer (10-15hrs); antibody-mediated response 3) *Type IV:* delayed cell-mediated response
How many surface receptors are in B-cells in the recognition stage of humoral immunity?
- An immunocompetent B cell has thousands of receptors for one antigen - Becomes activated when antigens bind to several of these receptors, links them together and is taken into the cell by *receptor-mediated endocytosis* NOT phagocytosis
What is anaphylaxis? Relate it to type I hypersensitivity
- Anaphylaxsis is an immediate and severe type I reaction - Anaphylactic shock is a sever, widespread acute hypersensitivity that occurs when an allergen such as bee venom or penicillin is introduced in the bloodstream of an allergic individual - Characterized by broncoconstriction, dyspnea (labored breathing), widespread vasodilation, circulatory shock, and sometimes sudden death - Relieved by epinephrine
*How antibodies render antigens useless* What is precipitation?
- Antibodies *link antigen molecules together* - Creates large complexes that cannot dissolve in solution - Easily removed by *immune clearance or phagocytosis by eosinophils*
Outline the classical pathway of activation.
- Antibody binds to antigen on microbe surface - changes shape to form Ag-Ab complex - change of shape exposes complement binding sites - sets off reaction cascade of complement proteins binding to exposed sites - Each step is an amplifying process --> *complement fixation:* results in the attachment of a chain of complement proteins to the antibody - C3 dissociates into C3a and C3b
Which cells are involved in the recognition stage of immunity?
- Antigen presenting cells - T cells
What is an antigen?
- Any molecule that triggers an immune response
Which complement proteins are involved in type III hypersensitivity?
- At sites of deposition (from precipitation) these complexes activate complement and trigger intense inflammation, causing tissue destruction. - Examples include autoimmune diseases such as glomerulonephritis and systemic lupus erythematosus, a widespread inflammation of the connective tissues.
What does clonal selection lead to in humoral immunity (during recognition stage)?
- B cell mitosis giving rise to numerous identical B cells programmed against that antigen - Many cells differentiate into *plasma cells* which mostly take up residence in the bone marrow and produce antibodies until they die
What is the time frame of response in type I hypersensitivity?
- Begins within seconds of exposure & usually subsides within 30 minutes
What is the function of a complement protein in nonspecific immunity?
- C3 breaks down into C3a and C3b - *C3a* initiates a reaction which leads to *inflammation* - *C3b* is the initiates various mechanisms. All which lead to *immune clearance, phagocytosis, or cytolysis*
Outline the alternate pathway of activation.
- C3 slowly and spontaneously dissociates into C3a and C3b - C3b binds to pathogen surface - Reaction cascade with an *autocatalytic effect* C3b leads to accelerated splitting of more C3 and production of more C3b - C3 dissociates into C3a and C3b
Where are B-cells 'born'?
- Synthesized in red bone marrow and remain there
What is the role of a complement protein in immune clearance?
- C3b binds Ag-Ab complexes to red blood cells and gets delivered to liver and spleen - Macrophages of liver and spleen destroy the Ag-Ab complex but do not harm RBC - *principal means of clearing foreign matter from the blood stream!*
What is the role of a complement protein in phagocytosis?
- C3b coats bacteria, viruses, and other pathogens to serve as binding site for phagocytes to internalize the complex - process is called *opsonization* and leads to more effective phagocytosis
What is the role of a complement protein in cytolysis?
- C3b splits C5 into C5a and C5b - C5a and C3a join in proinflammatory action - C5b binds to enemy cell and attracts other complements to form complex C5b678 which further binds with 17 other C9 complements. - Forms a ring called the *membrane attack complex* and creates hole in target cell which leads to cell rupture -- *leads to cytolysis of target cell*
What is the mechanism in mobilization of defenses?
- Causes redness and heat, an increase in local metabolic rate, promotes cell multiplication and healing, dilutes toxins, provides O2, nutrients, and waste removal
What is the time frame of response in type IV hypersensitivity?
- Cell-mediated reaction in which the signs appear about 12-72 hours after exposure -- *PER DOE, 24 hours after SECOND EXPOSURE*
*Chemical Agent* Interleukin
- Cyotkine produced by leukocytes and macrophages to stimulate other leukocytes
What is the function of memory T-cells in cellular immunity?
- Descended from cytotoxic T cells and are responsible for memory in cellular immunity
Which immune cells are destroyed in acquired immunodeficiency syndrome?
- Destroys Th cells
How do cyototoxic T-cells react in the attack/react stage of cellular immunity?
- Directly attack and destroy complex of antigen and MHCI protein, by delivering a lethal hit of chemicals that will destroy it
How does edema help tissue cleanup and repair?
- Edema causes *venous flow to decrease* and *lymphatic flow to increase* which favors the removal of bacteria and debris
Are intra or extra cellular pathogens involved in humoral immunity? Why?
- Effective against extracellular viruses, bacteria, yeasts, protozoans, and molecular (noncellular) pathogens such as toxins, venoms, and allergens
What is the function of cytotoxic T-cells in cellular immunity?
- Effectors of cellular immunity that carry out the attack on foreign cells - aka *T8, CD8, CD*+ because they have glycoprotein CD8 that are cell-adhesion molecules that enables T cells to bind to other cells
Which types of cells are involved in humoral immunity?
- Employs antibodies which do not directly destroy a pathogen but tag them for destruction - Detection of antigen for first time by B cell antibody (binds) -- activates B cell which secretes multiple copies of antibody with same specificity as membrane antibody
What cells express MHC-I proteins?
- Every nucleated cell of the body (not erythrocytes) - Proteins are constantly being produced in the cell and make their way to plasma membrane - On way, they pick up small peptides in the cytoplasm and display them - If it is a self-antigen (normal peptide), they do not elicit a T cell repsonse - If they are viral proteins or abnormal antigens made by cancer cells, they do elicit a T cell response - *Only cytotoxic cells (Tc) respond to MHC I proteins*
What is the first line of defense?
- External barriers; the skin and mucous membranes - *nonspecific resistance* = guard equally against a broad range of pathogens and effectiveness does not depend on prior exposure. Present from birth.
How does increased heat help tissue cleanup and repair?
- Facilitated by hyperemia that provides materials needed and heat that increases metabolism, mitosis, and tissue repair
How does the fibrin clot help tissue cleanup and repair?
- Fibrin clot may provide a scaffold for repair
*Cellular Agent* Reticular cells
- Fixed cells in the stroma of the lymph nodes and other lymphatic organs - act as APCs in the thymus, with a role in maturation of T cells
Which region of the body is drained by the right lymphatic duct? Outline the flow of lymph that enters into the right lymphatic duct (in order)
- Formed by the convergence of the right jugular, right subclavian, right bronchiomediastinal trunks in the *right thoracic cavity*. - Receives lymph drainage from the *right arm*, and *right side of the thorax and head* and empties into the *right subclavian vein*
What is the difference between AIDS and HIV?
- HIV is a virus that may cause an infection, but AIDS is a condition or a syndrome. Being infected with HIV can lead to the development of AIDS - AIDS develops when HIV has caused serious damage to the immune system
How are helper T-cells involved in the recognition stage of humoral immunity?
- Helper T cell binds to Ag-MHCP complex and triggers the secretion of interleukins that activate B cell
What is the function of the lymphocyte in nonspecific immunity?
- Helper T cells secrete chemotactic factors and colony-stimulating factors - Immune surveillance by natural killer (NK) cells
What is a transfusion reaction in type II hypersensitivity?
- Host antibodies react with foreign antigens on the incompatible transfused blood cells and mediate destruction of these cells. - Antibody can mediate cell destruction by activating the complement system to create pores in the membrane of the foreign cell.
Which antibodies are involved in type I hypersensitivity?
- IgE-mediated reaction
Which antibodies are involved in type II hypersensitivity?
- IgG and IgM attacks antigens bound to cell surfaces - Reaction leads to complement activation and either lysis or opsonization of the target cell
What is meant by negative selection leaves the body in a state of self-intolerance?
- Surviving, active T cells respond only to foreign antigens, not to one's own
What is the third line of defense?
- Immune system; defeats the pathogen but leaves the body with a 'memory' of it, enabling one to defeat it so quickly in future encounters that the pathogen causes no illness. - *specific defense* = results from prior exposure to a pathogen and usually provides future protection only against that particular one.
What is a secondary lymphatic organ and where are they located?
- Immunocompetent lymphocytes migrate to these organs only after they mature in the primary lymphatic organs - Lymph nodes, tonsils, and spleen
List the function of macrophages and identify which immune response they are associated with.
- Involved in both specific and nonspecific immunity *nonspecific immunity role* - Clean up tissue damage - phagocytize bacteria, tissue debris and dead and dying leukocytes and pathogens *specific immunity role* - Phagocytize pathogens and expended or damaged host cells - Act as antigen presenting cells
List the function of dendritic cells and identify which immune response they are associated with.
- Involved in both specific and nonspecific immunity *nonspecific immunity role* - phagocytic cells present in tissues that are in contact with the external environment - skin (Langerhan's), inner mucosal lining of the nose, lungs, stomach, and intestines. - very important in the process of antigen presentation *specific immunity role* - Act as antigen presenting cells -- migrates to lymph nodes and presents internalized antigens to cytotoxic and helper T cells
List the function of reticular cells and identify which immune response they are associated with.
- Involved in specific immunity - Fixed cells in the stroma of lymph nodes and other lymphatic organs - Act as APCs in the thymus with a role in the maturation of T cells
What is the composition of the fluid found in the cisterna chyli? Why?
- It contains the same composition as other lymph except the lymph in the cisterna chyli is *very fat-rich due to the large amount of chyle (fatty intestinal lymph) it receives after a meal.*
How do neutrophils kill?
- Kills via phagocytosis, digestion, and *respiratory burst* - When a bacteria is detected, neutrophils *degranulate* (discharge their lysosome enzymes into the tissue fluid), which catalyze a reaction called the *respiratory burst* - Neutrophil rapidly absorbs O2 and reduces it to superoxide anions (O2•-), which react with H+ to form hydrogen peroxide (H2O2) - Another lysosomal enzyme produces hypochlorite (HClO) from chloride ions in the tissue fluid
What are the mediator chemicals in mobilization of defenses?
- Kinins, histamine, and leukotrienes are secreted by damaged cells, basophils and mast cells, which *stimulates vasodialation that leads to hyperemia*
List the function of the Natural Killer cells and identify which immune response they are associated with.
- Large *lymphocytes* associated with the *nonspecific immunity* - *attack and destroy bacteria, transplanted tissues, and host cells that have become infected with viruses or turned cancerous* - Secrete proteins called *perforins* which bind to enemy cell and create a hole in its plasma membrane *kiss of death* - Secretes a group of protein-degrading enzymes called *granzymes* which enter pore made by perforins, destroy the target cell's enzymes and *induce apoptosis*
List the function of the T-lymphocytes and identify which immune response they are associated with.
- Large lymphocytes associated with *both specific and nonspecific immunity* - *Helper T cells are involved in both humoral and cellular immunity as well as nonspecific immunity. All other T cells are involved in cellular immunity ONLY.* *Specific Immunity* - Cytotoxic T cells directly attack and destroy enemy cells by producing perforin, granzymes, interferon, tumor necrosis factor, and other cytokines - Regulatory T cells limit the immune response by inhibiting multiplication and cytokine secretion by other T cells. - Memory T cells descended from cytotoxic T cells and are responsible for memory in cellular immunity. *Both* - Helper T cells recognize antigen fragments displayed by APCs with *MHC II proteins* and *secrete interleukins* that activate B, cytotoxic T, and NK cells, neutrophils, and macrophages.
Which region of the body is drained by the thoracic duct? Outline the flow of lymph that enters into the thoracic duct (in order)
- Larger and longer - Formed by the convergence of the two lumbar trunks into the *cisterna chyli*. - Receives lymph from *left bronchomediastinal*, *left subclavian*, and *left jugular trunks* and empties into the *left subclavian vein*. - Collectively it *drains all of the lower body below the diaphragm, left upper limb, and left side of head, neck and thorax*
What is the function of regulatory T-cells in cellular immunity?
- Limit the immune response by inhibiting multiplication and cytokine secretion by other T cells
How does metastasis effect lymph nodes?
- Lymphatic vessels are highly permeable so metastasizing cancer cells easily enter them and travel in the lymph - Tend to lodge in the first lymph node they encounter and multiply there, eventually destroying the node
What is specificity in specific immunity?
- Lymphocytes crucial to specific immunity: T cell receptors and antibodies produced by B cells recognize nonself or antigens to initiate an immune response - Specific sites on antigens that immune system recognizes are antigenic determinants or epitopes
What are the functions of monocytes and macrophages?
- Monocytes emigrate from bloodstream into connective tissues to become *macrophages* where they phagocytize pathogens - *Dendritic cell:* employ receptor-mediated endocytosis instead of phagocytize! - Some are wandering cells and others are fixed (*reticular cells*)
Which cells are responsible for tissue cleanup and repair?
- Monocytes the primary agents of cleanup arrive in 8 to 12 hours and become macrophages
What characteristics of mucous membranes make them barriers?
- Mucous physically ensnares microbes which are moved by cilia to the pharynx, swallowed and destroyed by stomach acid - Mucous, tears, and saliva also contain *lysozyme*, an enzyme that destroys bacteria by dissolving their cell walls
How do natural killer cells kill?
- NK cells bind to target cell and *release perforin, polymerize in a ring to create a hole in plasma membrane of target cell* - Hole allows for rapid inflow of water and salts - NK cell also secretes a group of enzymes called *granzymes, which enter through hole and destroy the target cell's enzymes and induce apoptosis*
What is the *respiratory burst* reaction?
- Neutrophil rapidly absorbs O2 and reduces it to superoxide anions (O2•-), which react with H+ to form hydrogen peroxide (H2O2) - Another lysosomal enzyme produces hypochlorite (HClO) from chloride ions in the tissue fluid *- Superoxide, hydrogen peroxide, and hypochlorite are highly toxic; they form a *chemical killing zone* around the neutrophil that destroys far more bacteria than the neutrophil can destroy by phagocytosis alone* - Kills neutrophil in process and damages connective tissues and can contribute to rheumatoid arthritis
Is the entire antigen responsible for the immune response?
- Only certain regions of the antigen yield an immune response -- *epitopes (antigenic determinants)* are binding sites for antibodies - One antigen can have numerous epitopes, each stimulating a different immune repsonse
What cells express MHC-II proteins?
- Only occur on APCs and display only foreign antigens - *Only helper cells (Th) respond to MHC II proteins*
How is pain useful in tissue cleanup and repair?
- Pain limits use of body part allowing for repair
What is the function of a tonsil and where are they located?
- Patches of lymphatic tissue located at the entrance to the pharynx, where they guard against ingested and inhaled pathogens *Three main sets of tonsils:* 1) single pharyngeal (adenoids) 2) pair of palatine tonsils (most often infected - tonsillitis, and removed, tonsillectomy) 3) numerous lingual tonsils
Describe lymphatic capillaries.
- Penetrate nearly every tissue of the body. - Closely associated with blood capillaries but are closed at one end. - Consists of a sac of thin endothelial cells that loosely overlap each other. Cells are tethered to surrounding tissue to prevent them from collapsing. - Not joined by tight junctions -- have large gaps so that bacteria, lymphocytes, and other cells and particles can enter along with the tissue fluid. - Overlapping endothelial cells act as valves that can open or close *- When tissue pressure is high, it pushes the flaps open and fluid flows into the capillary. When pressure is higher in the lymphatic capillary than in the tissue fluid, the flaps are pressed closed. --> PREVENTS BACKFLOW!!!*
Outline the lectin pathway of activation.
- Plasma proteins bind to carbohydrates on pathogen surface - Reaction cascade leading to C3b production
How is the remember/memory stage in humoral immunity useful?
- Primary response • protective antibodies delayed 3-6 hrs • naive B cells multiply • differentiate into plasma cells - Antibody titer begins to rise - Memory B cells mount a very quick secondary (anamnestic) response if re-exposed to *same* antigen. - IgM declines quickly - IgG remains elevated for weeks to years, conferring lasting protection. *- Memory does not last as long as it does in cellular immunity*
What is the goal in containment and destruction of pathogens?
- Priority of inflammation is to prevent pathogens from spreading throughout body
What is the function of helper T-cells in cellular immunity?
- Promote the action of cytotoxic T cells as well as playing key roles in humoral immunity and nonspecific resistance - aka *T4, CD4 or CD4+ because they have glycoprotein CD4 that are cell-adhesion molecules that enables T cells to bind to other cells
What is memory in specific immunity?
- Re-exposure to *SAME* pathogen, the body reacts so quickly that there is no noticeable illness.
What role do helper T-cells have in the attack/react stage of cellular immunity?
- Recognizes an Ag-MHCP complex, it *secretes interleukins* that exert three effects: 1) they attract neutrophils and natural killer cells 2) they attract macrophages, stimulate their phagocytic activity and inhibit them from leaving the area 3) they stimulate T and B cell mitosis and maturation
Where do B-cells achieve immunocompetence?
- Red bone marrow
Where are T-cells 'born'?
- Red bone marrow as descendants of hemopoietic stem cells
What is clonal deletion?
- Self-reactive T cells die and macrophages phagocytize them
What is anergy?
- Self-reactive T cells remain alive but unresponsive
What is the second line of defense?
- Several nonspecific defense mechanisms against pathogens that break through the skin or mucous membranes; leukocytes and macrophages, antimicrobial proteins, immune surveillance, inflammation, and fever. - *nonspecific resistance* = guard equally against a broad range of pathogens and effectiveness does not depend on prior exposure. Present from birth.
What is a hapten?
- Small molecules that are too small to be antigenic themselves but can stimulate an immune response by binding to a host macromolecule and creating a unique complex that the body recognizes as foreign - Penicillin is a hapten that is the most common drug allergy. Binds to host proteins and creates a complex that binds to mast cells and triggers massive release of histamine and other inflammatory chemicals -- can cause death from anaphylactic shock.
What is cross-reactivity?
- Some antibodies against foreign antigens react to similar self-antigens
What are some barriers to prevent inappropriate exposure?
- Some of our native antigens are not normally exposed to the blood - For example, a blood-testis barrier (BTB) normally isolates sperm cells from the blood
What are some changes in self-antigens?
- Some viruses and drugs may change the structure of self-antigens and cause the immune system to perceive them as foreign
What is the function of the neutrophil?
- Spends most of its life wandering in the connective tissues killing bacteria - Kills via phagocytosis, digestion, and *respiratory burst*
How is the remember/memory stage in cellular immunity useful?
- T cells that became memory cells are long-lived and much more numerous than naive T cells which require fewer steps to be activated and therefore respond to re-exposure to *same* antigens more rapidly
*Cellular Agent* Regulatory T (Tr) cells
- T cells that inhibit other T cells from multiplying or secreting cytokines - important especially in preventing autoimmune diseases but may also play defensive roles against infection and cancer and protect the fetus from maternal immune responses
*Cellular Agent* CD4 (T4) cells
- T lymphocytes with CD4 surface glycoproteins - helper and regulatory T cells
*Cellular Agent* CD8 (T8) cells
- T lymphocytes with CD8 surface glycoproteins - helper and cytotoxic T cells
What is natural active immunity? Give an example
- The production of one's own antibodies or T cells as a result of natural exposure to an antigen - When the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response
What is artificial active immunity? Give an example
- The production of one's own antibodies or T cells as a results of vaccination against diseases such as smallpox, tetanus, or influenza - A *vaccine* consists of either dead or attenuated (weakened) pathogens that can stimulate an immune response but cause little or no discomfort or disease.
What is a primary lymphatic organ and where are they located?
- The sites where B and T lymphocytes become immunocompetent; able to recognize and respond to antigens - Red bone marrow and thymus
What is purulent exudate?
- Then there is the formation of *pus which is a mixture of tissue fluid, cellular debris, dying neutrophils and microbes*
What happens to B-cells if they fail the immunocompetent test?
- They are eliminated in a process called *negative selection* Two forms of negative selection: 1) Clonal deletion 2) Anergy
What happens to T-cells if they fail the immunocompetent test?
- They are eliminated in a process called *negative selection* Two forms of negative selection: 1) Clonal deletion 2) Anergy
What do the surface receptors on the B-cells of humoral immunity detect?
- They detect epitopes on antigens and internalize them via receptor-mediated endocytosis. - Break it down and display the epitope on the MHC II protein which is recognized by helper T cell
How do antigen presenting cells work?
- When an APC encounters an antigen, it internalizes it by endocytosis, digests it into molecular fragments, and displays the relevant fragments (its epitopes) in the grooves of the MHC proteins - Lymphocytes and APCs talk to each other with cytokines called interleukins; chemical signals from one leukocyte to another
*Chemical Agent* Antibody (Ab)
- a gamma globulin produced by plasma cells in response to an antigen - *counteracts antigen by means of complement fixation, neutralization of toxins, agglutination, or precipitation*
*Chemical Agent* Perforin
- a protein produced by NK and Tc cells that bind to target cells, produces a hole, and admits granzymes into the cell
*Cellular Agent* Memory B cells
- activated B cells that do not immediately differentiate into plasma cells - act as a pool of B cells that can execute a quick T cell recall response upon reexposure to the same antigen that initially activated them
*Cellular Agent* Memory T cells
- activated T cells that not immediately differentiate into effector T cells - act as a pool of T cells that can execute a quick T cell recall response upon reexposure to the same antigen that initially activated them
*Cellular Agent* Dendritic cells
- branched, mobile APCs of the skin, mucous membranes, and lymphatic tissues - internalize antigen, migrate to lymph nodes, and present it to helper T and cytotoxic T cells
What characteristics of the skin make it a barrier?
- coated with diverse antimicrobial chemicals - *acid mantle* - a thin film of lactic acid that inhibits bacterial growth - sweat contains an antibacterial peptide called *dermicidin* - Keratinocytes, neutrophils, macrophages, and other cells produce peptides called *defensins* and *cathelicidins* that destroy bacteria, viruses, and fungi - Above defenses are enhanced by Vitamin D (calcitriol)
*Chemical Agent* Tumor necrosis factor (TNF)
- cytokine secreted by Tc cells that activates macrophages and kills cancer cells
*Cellular Agent* Plasma cells
- develop from B cells that have been activated by helper T cells - synthesize and secrete antibodies
*Cellular Agent* Cyotoxic T cells (aka: killer T, Tc, or CD8)
- effectors of cellular immunity - directly attack and destroy enemy cells - produce perforin, granzymes, interferon, tumor necrosis factor, and other cytokines
What does nonspecific resistance guard against?
- equally guard against a broad range of pathogens and effectiveness does not depend on prior exposure. Present from birth.
*Chemical Agent* Complement
- group of plasma proteins that help to destroy pathogens by cytolysis, phagocytosis, immune clearance, or nonspecific defense (inflammation)
*Cellular Agent* Naive lymphocytes
- immunocompetent lymphocytes that are capable of responding to an antigen but have not yet encountered one
What is the function of the spleen and where is it located?
- largest lymphatic organ located in the left hypochondriac region, inferior to the diaphragm - mainly acts as a filter for purifying the blood, removing microbes and worn out or damaged red blood cells - produces white blood cells and synthesize antibodies
*Chemical Agent* Antigen (Ag)
- molecule capable of triggering an immune response - usually a protein, polysaccharide, glycolipid, or glycoprotein
Which enzymes are released by cyototoxic T-cells in the attack/react stage of cellular immunity?
- perforin and granzymes; which kill the target cell in the same manner as we saw earlier for NK cells - interferons; which inhibit viral replication and recruit and activate macrophages, among other effects - tumor necrosis factor (TNF); which aids in macrophage activation and kills cancer cells
*Cellular Agent* Eosinophils
- phagocytize and degrade Ag-Ab complexes
*Cellular Agent* Macrophages
- phagocytize pathogens and expended or damaged host cells - act as antigen-presenting cells
What are lymphatic follicles and where are they found in the body?
- places in the body where lymphocytes and macrophages congregate in dense masses - come and go as the pathogens invade the tissues and the immune system answers the challenge - Relatively constant feature of lymph nodes, tonsils, and appendix. - In the distal portion of the small intestine, the ileum, they form clusters called *Peyer patches*
*Cellular Agent* Helper T (Th) cells
- play a central regulatory role in nonspecific defense and humoral and cellular immunity - recognize antigen fragments displayed by APCs with MHC-II proteins - secrete interleukins that activate B, cytotoxic C, and NK cells, neutrophils, and macrophages
*Chemical Agent* Granzyme
- proteolytic enzyme produced by NK and Tc cells - enters the pore made by perforins, degrade enzymes of the enemy cell, and induced apoptosis
What are the cardinal signs of inflammation? (bonus if they are in LATIN)
- redness (rubor) - heat (calor) - swelling (tumor) - pain (dolor)
*Cellular Agent* B cells
- serve as antigen-presenting cells in humoral immunity - differentiate into antibody-secreting plasma cells.
*Chemical Agent* Hapten
- small molecule initially unable to trigger an immune response by itself but able to bind to host molecules and produce a complex that is antigenic - may subsequently activate an immune response without binding to a host molecule
*How antibodies render antigens useless* What is complement fixation?
-Antibodies IgM and IgG bind to enemy cells and change shape, exposing their complement-binding sites - This initiates the binding of complement to the enemy cell surface and leads to inflammation, phagocytosis, immune clearance, and cytolysis - *primary mechanism of defense against foreign cells such as bacteria and mismatched erythrocytes*
Immunocompetent B cells exposed to antigen. Antigen binds only to B cells with complementary receptors
1) Antigen Recognition
List the three reasons why self-tolerance may fail.
1) Cross-reactivity 2) Abnormal exposure of self-antigens to the blood 3) Change in the structure of self-antigens
Predict the relative seriousness of removing the following organs from a 2-year-old child 1) a lymph node 2) the spleen 3) the thymus 4) palatine tonsils
1) The removal of a lymph node could potentially lead to fluid backup and obstruction in the lymphatic system which could potentially lead to elephantiasis. Lymph nodes are also responsible for filtering out 99% of impurities in the lymph before returning it to the bloodstream. The loss of a lymph node could compromise one's immune system and an ineffective immune response. 2) The removal of the spleen is possible but the toddler would be more vulnerable to infections and may have to be on daily antibiotics in order to avoid bacterial infections and certain vaccinations annually in order to avoid catching certain viruses. 3) Removing a thymus would most likely cause the 2-year to eventually pass away due to the inability to fully develop immunity. The thymus houses developing lymphocytes and secretes hormones that regulate their later activity. 4) There would be little to no consequences of removing the palatine tonsils. Many children have them removed and experience no serious side effects.
What are the four methods of pathogen destruction by activated complement?
1) inflammation 2) immune clearance 3) phagocytosis 4) cytolysis
How can a fever be beneficial?
1) promotes interferon activity 2) elevates metabolic rate and accelerates tissue repair 3) inhibits reproduction of bacteria and viruses - Stages of fever: onset, stadium, and defervesence
What are cytokines?
A class of chemicals that *regulate inflammation and immunity*. Small proteins that serve as a chemical communication network among immune cells. - Have paracrine/autocrine effects -- *Act at short range, usually between neighboring cells or on the same cell that secretes them*
Indicate if the given direction of lymph flow is correct or incorrect. A) Lymphatic capillaries to collecting vessels B) Lymph nodes to lymph capillaries C) Collecting vessels to lymphatic trunks D) Collecting ducts to collecting vessels E) Thoracic duct to cisterna chyli F) Right subclavian trunk to thoracic duct G) Intestinal trunk to right lymphatic duct H) Left lumbar trunk to thoracic duct I) Lower extremity lymph to thoracic duct J) Right head lymph to thoracic duct
A) Correct B) Incorrect C) Correct D) Incorrect E) Incorrect F) Incorrect G) Incorrect H) Correct I) Correct J) Incorrect
On the first exposure to an antigen, T helper cells ______ A) become activated and increase in number. B) cause inflammation. C) cause skin lesions. D) cause shock.
A) become activated and increase in number.
Use the drop-down boxes to indicate whether the following would be associated with increased or decreased inflammation. A) Histamine release B) Vasoconstriction of arterioles C) Heparin release D) Complement fixation E) Hypoxia F) Reduced temperature G) Hyperemia H) Basophil activation I) Regulatory T-cell activity J) Aspirin
A) increased B) decreased C) increased D) increased E) decreased F) decreased G) increased H) increased I) decreased J) decreased
Indicate whether the following are associated with adaptive or nonspecific immunity. A) skin B) antibodies C) antigens D) complement (classical pathway) E) hypodermal areolar connective tissue F) stratified squamous epithelium G) keratinized epithelium H) major histocompatibility complexes I) immunoglobulin
A) nonspecific defense B) specific immunity C) specific immunity D) specific immunity E) nonspecific defense F) nonspecific defense G) nonspecific defense H) specific immunity I) specific immunity
Indicate if the following are associated with adaptive or nonspecific defenses. A) B lymphocytes B) T lymphocytes C) Neutrophils D) Cytotoxic T cells E) Plasma cells F) Memory T cells G) CD4+ cells H) Eosinophils
A) specific immunity B) specific immunity C) nonspecific defense D) specific immunity E) specific immunity F) specific immunity G) specific immunity H) nonspecific defense
Where are lymphatic capillaries *not* present?
Absent from central nervous system, cartilage, cornea, bone, and bone marrow.
STEP 3
Antigen and enzyme mix in phagolysosome
STEP 4
Antigen is degraded
STEP 5
Antigen residue is voided by exocytosis
Where is the body's thermostat?
Anterior hypothalamus
What is the function of immunity in the lymphatic system?
As the lymph circulates throughout the system on its way back to the bloodstream, it circulates through the lymph nodes. The primary role of the lymph nodes is to *filter out foreign cells or chemicals by way of immune cells. They are capable of detecting anything that is potentially harmful to the body and mounting an immune response.*
Which of the following is true regarding interferon? A) Interferon is produced as a specific response to a specific virus. B) Interferon is produced by one cell to warn a neighbor cell. C) Interferon is able to save the cell that makes it. D) Interferon kills all bacteria. E) Interferon kills the cell that makes it.
B) Interferon is produced by one cell to warn a neighbor cell.
All of the following processes can be activated by complement except ____. A) inflammation B) antibody production C) cytolysis D) opsonization E) None of these choices are correct.
B) antibody production
IgE molecules attach to A) mast cells via their variable region B) mast cells by their constant region C) T helper cells by their variable region D) plasma cells by their constant region
B) mast cells by their constant region
When do skin lesions associated with type IV hypersensitivity reactions occur? A) 24 hours after first exposure B) 48-72 hours after first exposure C) 24 hours after second exposure D) 3 weeks after second exposure
C) 24 hours after second exposure
What is the function of fluid recovery in the lymphatic system?
Capillaries are only capable of reabsorbing 85% of the fluid delivered to them. So the lymphatic system is *responsible for reabsorbing the remaining 15% that would otherwise cause death from circulatory failure within hours. It filters and delivers this fluid back to the blood.*
What are the different lymphatic trunks?
Collecting vessels *converge to form lymphatic trunks* - each draining a major portion of the body. 1) jugular trunk 2) subclavian trunk 3) bronchomediastinal trunk 4) intercostal trunk 5) intestinal trunk 6) lumbar trunk
Which of the following is not necessary for IgE mediated hypersensitivity? A) B cells B) IgE antibodies C) Mast cells D) Neutrophils
D) Neutrophils
Which of the following is true regarding antigens? A) They have a molecular weight of around 1000 kDa. B) They have one antigenic determinant (epitope). C) They are considered normal by the immune system. D) They have multiple antigenic determinants (epitopes). E) They are usually made of lipids.
D) They have multiple antigenic determinants (epitopes).
What is the function of the eosinophil?
Found especially in the mucous membranes, standing guard against parasites and allergens (allergy-causing agents) - Help to kill parasites such as tapeworms and roundworms - Promote action of basophils and mast cells - Phagocytize and degrade Antigen-Antibody (Ag-Ab) complexes - Secrete enzymes that degrade and limit action of histamine and other inflammatory chemicals that could cause tissue damage if left unchecked
What cells participate in immune surveillance?
NK Cells
In humoral immunity, how do antibodies render antigens useless in the react stage?
Once released by a plasma cell, antibodies use four mechanisms to render antigens harmless: 1) Neutralization 2) Complement Fixation 3) Agglutination 4) Precipitation
B Cells have receptors for how many different epitopes?
One; They have hundreds of receptors but only recognize NON
*How antibodies render antigens useless* What is neutralization?
Only certain regions of an antigen are pathogenic -- antibodies can neutralize an antigen by masking these active regions
What is the structure of the spleen?
Parenchyma consists of layers of two tissue types: 1) *red pulp* - consists of sinuses gorged with concentrated erythrocytes -- Mechanical filtration of red blood cells. 2) *white pulp* - consists of lymphocytes and macrophages aggregated like sleeves along small branches of the splenic artery -- Active immune response through humoral and cell-mediated pathways.
*Cellular Agent* Neutrophils
Phagocytize bacteria; secrete bacterial oxidizing agents; secrete cytokines that activate more leukocytes
STEP 1
Phagocytosis of Antigen
In the react stage of humoral immunity, which cells make the antibodies?
Plasma cells that differentiated from B cells
*Chemical Agent* Kinins
Plasma proteins that are activated by tissue injury and stimulate vasodilation, capillary permeability, and pain; include bradykinin
STEP 6
Processed antigen fragments (epitopes) displayed on macrophage surface
*Cellular Agent* Eosinophils
Produce antiparasitic oxidizing agents and toxic proteins; stimulate basophils and mast cells; limit action of histamine and other inflammatory chemicals
*Cellular Agent* Endothelial Cells
Produce cell-adhesion molecules to recruit leukocytes; secrete platelet-derived growth factor
*Chemical Agent* Complement
Proteins that promote phagocytosis and cytolysis of pathogens, activate and attract neutrophils and macrophages, and stimulate basophils and mast cells to secrete inflammatory chemicals
*TRUE or FALSE* A person who is HIV-positive and has a Th (CD4) count of 1,000 cells/μL does not have AIDS.
TRUE
*TRUE or FALSE* Histamine and heparin are secreted by basophils and mast cells
TRUE
*TRUE or FALSE* Perforins are employed in both nonspecific resistance and cellular immunity
TRUE
*TRUE or FALSE* T lymphocytes undergo clonal deletion and anergy in the thymus.
TRUE
*TRUE or FALSE* The white pulp of the spleen gets its color mainly from lymphocytes and macrophages
TRUE
What is the function of a complement protein in specific immunity?
The *classical pathway* requires an antibody to get it started; thus it is part of specific immunity - *Complement fixation* C1 initiates the reaction cascade
What is lymphadenopathy?
The collective term for all lymph node diseases
Which of the following epithelial types is present in the trachea? a) Ciliated pseudostratified columnar with goblet cells that have cilia that are motile b) Ciliated pseudostratified columnar with goblet cells that have cilia that are non-motile c) Stratified columnar epithelium d) Simple cuboidal epithelium
a) Ciliated pseudostratified columnar with goblet cells that have cilia that are motile
A helper T cell can only bind to another cell that has a. MHC-II proteins b. an epitope c. an antigen-binding site d. a complement-binding site e. a CD4 protein
a. MHC-II proteins
Which of these is a macrophage? a. a microglial cell b. a plasma cell c. a reticular cell d. a helper T cell e. a mast cell
a. a microglial cell
The respiratory burst is used by __________ to kill bacteria a. neutrophils b. basophils c. mast cells d. NK cells e. cytotoxic T cells
a. neutrophils
Interferons are secreted from cells infected by __________.
viruses