Immuno Sakai Q's

A 2 year old boy is evaluated for a severe combined immunodeficiency disease. His bone marrow has normal cellularity. Radioactive tracer studies demonstrate a normal number of T-cell precursors entering the thymus, but no mature T lymphocytes are found in the blood or peripheral organs. Cells populating the thymus are found to lack CD3. Which of the following capabilities would his cells lack? A. Ability to bind cell-bound peptides B. Ability to express CD4/CD8 co-receptors C. Ability to produce terminal deoxyribonucleotidyl transferase D. Ability to proliferated in response to specific antigen E. Ability to rearrange T-cell receptor gene segments

D

A 2-year old boy is admitted to the hospital for workup of a possible immunologic disorder. His history is remarkable for the occurrence of multiple skin infections involving Staphylococcus, Pseudomonas, and Candida. On examination the child has cervical lymphadenopathy and mild hepatosplenomegaly. Blood tests reveal an elevated erythrocyte sedimentation rate and neutrophilia. The nitroblue tetrazolium dye reduction test and neutrophil oxidative index are negative. What is the most likely defect in this child? A. C3 deficiency B. Deficiency of CD18 C. Deficiency of myeloperoxidase D. NADPH oxidase deficiency E. Phagocyte granule structural defect

D

A 50 year old woman with severe rheumatoid arthritis is started on infliximab (anti-tumor necrosis factor-alpha). This therapy has been shown to increase the production of CD25-positive T cells. Which of the following is likely, therefore, to become elevated in this patient? A. Interferon-gamma B. Interleukin-1 C. Interleukin-2 D. Interleukin-10 E. Transforming growth factor-beta

D

A 64-year old man undergoes surgery to excise 18 inches of bowel with adenocarcinoma. When the tissue and draining mesenteric lymph nodes are sent for pathologist's examination, the Peyer's patches are ntoed to be hyper plastic with IgA-secreting plasma cells, but there is no secretory IgA found in the lumen of the colon. Which of the following changes in the bowel epithelium could explain this finding? A. Failure of isotope switching B. Failure of variable domain gene-segment rearrangement C. Loss of J chain synthesis D. Loss of the poly-immunoglobin receptor E. Loss of TH-2 cells

D

A woman with advanced metastatic breast cancer undergoes a radical mastectomy, followed by irradiation and chemotherapy. After a 2 year remission, a metastatic focus appears, and she enrolls in a experimental treatment protocol. In it, a sample of her aspirated bone marrow is treated with GM-CSF, TNF-a, and IL-2, then pulsed with membrane fragments on her tumor cells and re-infused. Which of the following cell subpopulations is the most directly targeted by this treatment? A. B lymphocytes B. Cytotoxic T lymphocytes C. NK cells D. TH-1 cells E. TH-2 cells

D

An 8 year old boy is diagnosed with acute lymphoblastic leukemia. Flow cytometry is used to determine the immunophenotype of the malignant cells. The patient's cells are evaluated with monoclonal antibodies for MHC class II, CD19, and CD34, and are found to have high levels of fluorescence with all of these markers. They also possess cytoplasmic mu heavy chains. What is the developmental stage of these cells? A. Immature B cell B. Lymphoid progenitor cell C. Mature B cell D. Pre-B cell E. Pro-B cell

D

Isotype switching during B-cell ontogeny dedicates mature B cells to production of a single heavy chain isotope, except in the case of IgM and IgD, which can be expressed concomitantly. How is this expression of both isotypes simultaneously possible? A. Allelic exclusion B. Allelic codominance C. Affinity maturation D. Alternative RNA splicing E. Somatic hypermutation

D

The blood from an 8-year old boy was analyzed by flow cytometry. The cells were treated with fluorescent-labeled antibodies to various cell surface markers before they were evaluated by flow cytometry. Which of the following markers would identify the B lymphocyte in this sample? A. CD3 B. CD4 C. CD8 D. CD19 E. CD56

D

Toxoplasma gondii is an intracellular parasite that lives inside phagocytic and nonphagocytic cells by generating its own intracellular vesicle. This may allow it to avoid recognition and killing by CD8+ lymphocytes, which require the presentation of foreign peptides transported into the endoplasmic reticulum and loaded onto MHC molecules that have: A. A B2 domain instead of a B2 micro globulin B. Invariant chains C. A peptide-binding groove D. A single transmembrane domain E. Two similar chains

D

A 12 year old child is diagnosed with a T cell lymphoma. The phenotype of the malignant cell matches that of normal progenitor cells that leave the bone marrow to enter the thymus. What cell surface markers would you expect to find on the malignant cells? A. CD4-, CD8-, TCR- B. CD4-, CD8-, TCR+ C. CD4-, CD8+, TCR+ D. CD4+, CD8-, TCR+ E. CD4+, CD8+, TCR+

A

A 62 year old accountant developed a solid tumor that is unresponsive to chemotherapy. He elects to participate in an experimental treatment protocol to stimulate his own immune effector cells to recognize and kill the malignant cells. The tumor cells are found to have no expression of MHC class I antigens. Which of the following in vitro treatments of his tumor cells is likely to stimulate the most effective immune response when re-infused into the patient? A. IFN-y B. IL-2 C. IL-8 D. IL-10 E. TNF-B

A

A patient with advanced metastatic melanoma decides to join an experimental treatment protocol in the hope that it will cause regression of his tumor masses. Malignant cells are aspirated from several of his lesions and transfected in vitro with the gene encoding IL-3 production. The transfected tumor cells are then re-infuces into the patient. Mobilization of which of the following cells from the bone marrow would be likely to result from this treatment? A. Antigen presenting cells B. B lymphocytes C. NK cells D. Plasma cells E. T lymphocytes A

A

Before 1960, children with enlarged thymus glands were frequently irradiated to functionally ablate this organ, whose role was not yet known. Over the lifetime of such individuals, which of the following conditions was likely to develop? A. Depressed immune surveillance of tumors B. Depressed oxygen-dependent killing by neutrophils C. Depressed primary response to soluble antigens D. Increased cellularity of lymph node parametrical areas E. Increased tendency toward atopy

A

It has been learned in several experimental systems that proliferation and differentiation of T lymphocytes in response to tumor cells is low because tumor cells lack the necessary costimulatory molecules for lymphocyte activation. If melanoma cells from a patient were induced to express these costimulatory molecules by transfection, production of an effective anti-tumor response might occur. Which of the following molecules would be the best candidate for transfection of tumor cells to achieve this end? A. B7 B. CD2 C. CD4 D. CD28 E. LFA-1

A

Up until the 1970's tonsillectomies were routinely performed on children with swollen tonsils. This procedure has lost its widespread appeal as we have learned the important role of mucosal-associated lymphoid tissue (MALT) in the protective immune response. What is the major role immunoglobin produced by the MALT? A. A dimeric immunoglobulin with secretory component B. A monomeric immunoglobin that crosses the placenta C. A monomeric immunoglobulin bound by mast cells D. A monomeric immunoglobulin that opsonizes E. A pentameric immunoglobulin that activates complement

A

A 42-year old Nigerian man who is in the US visiting with his brother comes into the hospital clinic. He complains of several months of weight loss, night sweats, mild sputum production, and the spitting up of blood. You run a PPD skin test and the results are positive. What can you conclude from this results? A. A cell-mediated immune response has occurred B. A humoral immune response has occurred C. The B-cell system is functional D. The B- and T-cell systems are functional E. The neutrophilic phagocyte system is functional

A *the TB skin test is the classical clinical demonstration of the function of the delayed type hypersensitivity response - causes a cell-mediated reaction cause by sensitization of TH1 cells

A 56 year old homeless alcoholic, a febrile man is brought to the emergency department after a difficult night during which his coughing kept everyone at the shelter awake. On arrival his pulse is rapid, and his breathing is labored with diffuse rates. Endotracheal aspirates produce a mucopurulent discharge containing numerous gram-positive cocci in chains. His serum contains higher titers of IgM antibodies specific for the polysaccharide capsule of Streptococcus pneumonia. The effector mechanism most likely to act in concert with this early IgM production to clear infection is: A. ADCC B. Complement-mediated opsonization C. Cytotoxic T lymphocytes D. LAK cells E. NK cells

B

A patient is suffering from lymphadenopathy and splenomegaly. He has greatly increased number of lymphocytes, reduced numbers of platelets, and autoimmune anemia. When his peripheral blood leukocytes are exposed to T-cell mitogens, they proliferate wildly, even for weeks after the mitogenic stimulus is removed. Which of the following is most likely to be the genetic defect? A. Absence of complement B. Absence of Fas C. Absence of interferon-gamma (IFN-y) D. Absence of perforin E. Absence of TNF

B

A rabbit hunter in Arkansas is diagnosed with ulceroglandular tularemia and treated with streptomycin. Within a week, he returns to the hospital. The tularemia papule, lymphadenopathy, and bacteremia have resolved, but he has now developed a raised itchy skin rash and fever. The drug was discontinued, and the symptoms subsided. What was the role of streptomycin in this case? A. It acted as a B-cell mitogen B. It acted as a hapten C. It acted as a provider of co-stimulatory signals D. It acted as a super antigen E. It acted as an immunogen

B

A two-year old child who suffered recurrent bacterial infections is evaluated for immunological deficiency. The child has age-normal numbers of CD19+ and CD3+ cells in there peripheral blood and an extreme neutrophilia. The nitroblue tetrazolium dye reduction test is normal. What is the most likely defect in this child? A. Absence of CCR4 B. Absence of CD18 C. Absence of IL-1 D. Absence of IL-4 E. Absence of TNF-a

B *child has LAD, which is a genetic defect of CD18 -CD18 is an essential component of a number of interns, absence of these molecules causes the inability of WBC's to migrate to the site of inflammation -CD18 is a component of LFA-1, CR3, and CR4

A 4 year old is evaluated for a possible immunological deficiency. He has suffered repeated infections of mucosal-surface pathogens and has shown delayed development of protective responses to the standard childhood vaccinations. Immunoelectrophoresis of his serum demonstrates absence of a macro globulin peak, and his sputum is devoid of secretory IgA. Normal numbers of B lymphocytes bearing monomeric IgM are found by flow cytometry, and serum levels of monomeric IgA, IgE, and each of the 4 subisotypes of IgG are normal. Which of the following deficiencies could account for these findings? A. Absence of CD40 B. Absence of J chains C. Absence of IL-4 D. Absence of Tdt E. Absence of TH-2 cells

B IgM and secretory IgA are similar in that they are held together by a J chain synthesized by the B cell or plasma cell. Without the J chain, IgM would exist only in monomeric form, and the macro globulin peak would be absent on electrophoresis, and the child would have delayed development of protective responses to vaccination and would be especially susceptible to infectious agents crossing mucosal surfaces

An 18 year old member of a college soccer team is seen by a physician because of chest tightness and dyspnea on exertion. A 15-cm mediastinal mass is detected radiographically. Eighty percent of the white blood cells in the peripheral blood are small, abnormal lymphocytes with lobulated nuclei and scant cytoplasm. Immunophenotyping of the abnormal cells shows them to be CD4+ and CD8+. Where would such cells normally be found in the body? A. Bone marrow B. Peripheral blood C. Thymic cortex D. Thymic medulla E. Splenic periarteriolar lymphoid sheaths

C

During WWII, when quinine was used as a prophylactic against malaria infections in US personnel on long term assignment to the south pacific, a small portion of the soldiers developed blackwater fever (chronic kidney damage from the autoimmune effects of complement-mediated hemolysis of quininized RBC's). In this case, quinine played the role of: A. Autoantigen B. Carrier C. Hapten D. Immunogen E. Reagin

C

Herpes simplex virus are extremely successful pathogens because they have a variety of immunologic evasion mechanism. For example, both HSV 1 and 2 depress the expression of MHC I molecules on the surface of infected cells. Which co-receptor's binding would be inhibited by this technique? A. CD2 B. CD4 C. CD8 D. CD16 E. CD56

C

Human infections with Mycobacterium leprae express a spectrum of clinical presentation depending on the extent and expression of their immune response to the intracellular organism. On one end of the spectrum, patients with tuberculoid leprosy produce an effective cell-mediated immune response, which is successful at killing the intracellular organism and, unfortunately produces tissue damage. Patients with tuberculoid leprosy have granulomas that have elevated amounts of IL-2, IFN-y, and TNF-a. The immune cell responsible for this pattern of cytokine production if the: A. Cytotoxic T lymphocyte B. Epithelioid Cell C. TH-1 cell D. TH-2 cell E. Macrophage

C

There is evidence that the immunologic pathway that distinguishes the selection between the two forms of leprosy depends on the initial means of antigen presentation, as well as individual human differences in response. If early events of antigen recognition elicit productions of IL-4, IL-5, IL-6, and IL-10, lepromatous leprosy is more likely to result, with the outcome of failure to mount a protective delayed-type hypersensitivity response. What differential characteristic of the lepromatous form is predicted based on the fact of overproduction of IL-4, IL-5, IL-6, IL-10, IL-13 and TGF-B in lepramtous lesions? A. Autoimmunity B. Granuloma formation C. Hypergammaglobulinemia D. Immediate hypersensitivity E. Inflammation

C

It has been learned in animal experiments that there are advantages to eliciting nonspecific inflammation at the site of inoculation of antigen toward the ultimate development of a protective immune response to that immunogen. Which of the following substances, if introduces with a vaccine, would serve the purpose of attracting a neutrophilic infiltrate into that area? A. Complement component 3b B. Immunoglobulin G C. IL-8 D. Myeloperoxidase E. TNF-a

C *Chemotactic for neutrophils

An antibody preparation is being in a laboratory protocol to study B lymphocytes. The preparation does not activate the cells or cause capping. It does not cause precipitation of its purified ligand, and it does not cause agglutination of latex beads covalently coupled to its ligand. Which of the following is the most likely antibody preparation? A. Monoclonal anti-CD19 IgG B. Monoclonal anti-CD56 IgG C. Papain-treated anti-CD19 IgG D. Papain treated anti-CD56 IgG E. Pepsin-treated anti-CD19 IgG F. Pepsin-treated anti-CD56 IgG

C *treatment of IgG with papain yields two monovalent antigen binding Fab fragments and destroys the function of the Fe portion of the molecule - Ig's that are disrupted this way lose their ability to cross-link the receptors on cells, to promote precipitation or agglutination, and to activate cells by providing the first stimulatory signal

A 3 year old boy has had several bouts of pneumonia. Streptococcus pneumoniae was isolated and identified in each of the cases. The child was treated with penicillin each time, and the condition resolved. He is now being evaluated for a potential immunologic deficiency. Serum electrophoresis shows age-normal values for all isotypes of immunoglobulin, but serum levels of some components of complement are depressed. Which of the following deficiencies could explain his problem? A. C1 B. C2 C. C3 D. C4 E. C5

C Streptococcus pneumoniae is an extracellular, encapsulated bacteria

An elderly man with diabetes develops a blister on the heel of his foot, which becomes infected. Although nursing staff in the home where he is a resident clean and treat the wound with topical antibiotic ointment, he develops a fever and hypotension, and desquamating rash spreads from the site of the original blister. How does the toxin responsible for his symptoms cause these signs? A. It acts as an IL-1 homologue B. It activates B lymphocytes polyclonally C. It activates complement D. It cross-links MHC class II molecules to TCR's polyclonally E. It stimulates neutrophils

D *TSST-1 does not have an effect on complement

A germline B lymphocyte possesses 200 distinct V region genes, 5 J region genes, 2 isotypic possibilities to rearrange for its selection of light chain synthesis. Assuming no recombinational inaccuracies, how many distinct idiotypes could be produced by combining this coding sequence with one heavy chain? A. 100 B. 205 C. 400 D. 1000 E. 2000

D *multiply the number of V regions by the number of J regions

In a lifetime, a person may receive a dozen or more tetanus toxoid inoculations. When boosters are administered at 10-year intervals, which of the following would be true of the B lymphocytes that respond? A. Their receptors would have high avidity B. They would be large and highly metabolic C. They would have low levels of adhesion molecules D. They would have surface IgG, IgA, or IgE E. They would have surface IgM

D - avidity decreases with repeated booster inoculations - primary response is switched to secondary response, and undergoes class switching

A patient with a B-cell lymphoma is referred to an oncology clinic for the analysis of his condition. The malignant cells are found to be producing IgM monomers. Which of the following therapeutic regimens is most likely to specifically destroy the malignant cells and no other B cells? A. Anti-CD3 antibodies plus complement B. Anti-CD19 antibodies plus complement C. Anti-CD20 antibodies plus complement D. Anti-idiotype antibodies plus complement E. Anti-Mu chain antibodies plus complement

D Treatment with anti-idiotype antibodies plus complement would specifically kill only malignant cells, and leave all other B lymphocytes unharmed

A 26 year old obstetric patient becomes ill during the first trimester of pregnancy with fever and lymphadenopathy. She is found to have a rising titer of anit-Toxoplasma gondii antibodies. She delivers a full-term baby with no apparent signs of in utero infection. The best test to diagnose acute infection in the neonate would be a parasite-specific ELISA for which isotope of immunoglobulin? A. IgA B. IgD C. IgE D. IgG E. IgM

E

A 4-year old Caucasian boy is brought to his pediatrician with complaints of abnormal bruising and repeated bacterial infections. A blood work-up reveals thrombocytopenia and neutropenia and the presence of numerous small, dense lymphoblasts with scant cytoplasms. Immunophenotyping of the abnormal cells determines them to be extremely primitive B cells, which are CD19+, HLA-DR+, and Tdt+. Which of the following best describes the status of immunoglobulin chain synthesis most likely in these cells? A. IgM monomers inserted in the membrane B. IgM monomers persent in the cytoplasm C. Mu chains inserted in the membrane D. Mu chains present in the cytoplasm E. No immunoglobulin chain synthesis

E

A 4-year old boy is referred to a specialist for the diagnosis of a possible immunologic problem. The child has extremely elevated white blood cell counts with a profound lymphocytosis. A biopsy performed on a cervical lymph node reveals extreme hypocellularity in both cortical and paracortical areas. Absence of which of the following leukocytes surface molecules could result in this clinical picture? A. Addressions B. Chemokines C. Immunoglobulin family cell adhesion molecules D. Integrins E. L-selectins

E

A lymph node biopsy of a 6-year old boy shows markedly decreased numbers of lymphocytes in the parametrical areas. Analysis of his peripheral blood leukocytes is likely to show normal to elevated numbers of cells expressing surface: A. CD2 B. CD3 C. CD4 D. CD8 E. CD19

E

A 6- year old child is taken to his pediatrician because the parents are alarmed about an indurated fluctuant mass on the posterior aspect of his neck. The mass is non-tender and shows no sign of inflammation. The child is examined carefully and no other masses are found. The pediatrician submits a biopsy of this area to a pathologist, who reports back that the mass is a lymph node with markedly increased numbers of cells in the cortical area. Fluorescent antisera to which of the cell surface markers is most likely to bind to cells in this area? A. CD2 B. CD3 C. CD4 D. CD16 E. CD19

E *the cortex of lymph nodes is a B-lymphocyte area

A young woman with acute myeloblastic leukemia is treated with intensive chemotherapy and achieves remission of her symptoms. Because the prognosis for relapse is relatively high, a bone marrow transplant is undertaken in her first remission. Which of the following cytokines administered with the bone marrow cells would have the beneficial result of stimulating lymphoid-cell development from the grafted stem cells? A. IL-1 B. IL-2 C. IL-3 D. IL-6 E. IL-7

E The cytokine most strongly associated with stimulation of production of lymphoid cells from the bone marrow is interleukin 7

A radioactive tracer dye is injected subcutaneously into the forearm of an experimental subject. What is the first area of the first draining lymph node that would develop significant radioactivity? A. Cortex B. Medulla C. Paracortex D. Primary follicle E. Subcapsular sinus

E subcapsular sinus>primary follicle>medulla>paracortex>cortex