Immuno Exam 2 Questions
41. Which of the following molecules is NOT important in the interaction between a cytolytic T lymphocyte and a target cell? A. B7‐1 B. ICAM‐1 C. LFA‐1 D. T cell receptor E. Class I MHC
A. B7‐1
8. Which of the following molecules is expressed by a mature T cell that functions as a helper T cell? A. CD4 B. CD8 C. GlyCAM‐1 D. lgA E. lgG
A. CD4
59. The germinal center reaction is an important part of the antigen‐dependent development of B cells. Through which mechanisms does antigen‐dependent activation of B cells occur? A. Clonal expansion, class switching, somatic hypermutation and differentiation B. Clonal expansion, , immunoglobulin gene rearrangement, and Ab production C. Somatic hypermutation, immunoglobulin rearrangement and activation of the B cell D. Clonal expansion, proliferation, class switching and allelic exclusion E. Allelic exclusion, immunoglobulin gene rearrangement, activation and clonal expansion
A. Clonal expansion, class switching, somatic hypermutation and differentiation
53. Which of the following descriptions about affinity maturation is correct? A. Depends on somatic mutation of V genes B. Depends on negative selection of B cells that can bind antigen in the germinal center C. Depends on antigen processing and presentation by dendritic cells within the germinal center D. Depends on the autoimmune regulator (AIRE) gene E. Depends on somatic recombination of Ig V genes
A. Depends on somatic mutation of V genes
55. Antibody feedback is mediated by which of the following molecules? A. Ig Fc(gamma)RIIB B. Ig FcE C. Ig Fc(gamma)RI D. CR1 E. IgM
A. Ig Fc(gamma)RIIB
58. Naïve B cells require several signals in order to become activated. Which are these signals? A. Signal 1 from antigen through the B cell receptor and signal 2 from CD4 positive T‐cells B. Signal 1 from antigen through the B cell receptor and signal 2 from CD8 positive T‐cells C. Signal 1 from CD4 positive T‐cells and signal 2 from follicular dendritic cells D. Signal 1 from CD4 positive T‐cells and signal 2 from cytokines produced by macrophages E. Signal 1 from antigen through MHC molecules and signal 2 from cytokines produced by macrophages
A. Signal 1 from antigen through the B cell receptor and signal 2 from CD4 positive T‐cells
60. B‐cells can produce five different classes of antibodies. Antibodies belonging to the different classes have different effector mechanisms. Transport of antibodies from mother to the fetus (transcytosis) is important to protect the child against disease during the first months after birth. Which one of the following sentences describes this situation most accurately? A. Transportation of IgM and IgG to the fetus provides the child with antibodies that, through opsonization and neutralization, may protect against several diseases B. Transportation of IgG and IgE to the fetus leads to protection of the child through different effector mechanisms towards the same antigens that the mother has generated antibodies towards C. Transportation of IgM to the fetus provides the child with antibodies that, through opsonization and neutralization, may protect against several diseases D. Transportation of IgG to the fetus leads to protection of the child through opsonization and neutralization and thus may protect against several diseases
A. Transportation of IgM and IgG to the fetus provides the child with antibodies that, through opsonization and neutralization, may protect against several diseases
6. The basic structure of a T cell receptor consists of A. a membrane‐bound alpha/beta or gamma/delta heterodimer. B. a complex of disulfide‐linked heavy and light chains. C. covalently linked CD3 and CD247 molecules. D. peptide‐MHC complexes. E. soluble antigen‐binding homodimers.
A. a membrane‐bound alpha/beta or gamma/delta heterodimer.
9. Th1 cells secrete cytokines which A. activate macrophages. B. increase susceptibility to allergic reaction C. inhibit macrophage secretion of inflammatory cytokines D. stimulate B cells to secrete neutralizing antibodies E. stimulate proliferation of Th2 cells
A. activate macrophages.
18. The role of terminal deoxynucleotidyl transferase (TdT) in development of antibody diversity is to A. add/remove nucleotides of V, D, and J genes. B. fuse VD and J segments together in heavy chains. C. increase binding affinity of antibody for antigen. D. join CL to CH1, CH2, CH3, or CH4 domains. E. transfer VL alleles from maternal to paternal chromosomes.
A. add/remove nucleotides of V, D, and J genes.
17. Serum immunoglobulins containing both maternally and paternally derived VN light chains are found within an individual. A given B cell, however, expresses only maternally derived or paternally derived VN chains but never both. This finding is the result of A. allelic exclusion. B. antibody diversity. C. isotype switching. D. junctional diversity. E. random VD and VDJ joining.
A. allelic exclusion.
16. A 2‐year‐old child exposed to an antigen for the first time already possesses a B cell with immunoglobulin specific for that antigen. This finding is best explained by A. antigen‐independent immunoglobulin gene rearrangements. B. antigen stimulation of T cell cytokine production. C. maternally derived antibodies to that antigen. D. memory B cells that recognize the antigen. E. somatic hypermutation of immunoglobulins.
A. antigen‐independent immunoglobulin gene rearrangements.
21. What will be the fate of an early thymocyte that fails to express IL‐7 receptors? A. apoptotic cell death B. development as a JG T cell C. development as an NKT cell D. failure to traffic to the thymus E. maturation along the B‐cell lineage
A. apoptotic cell death
10. A T cell which binds antigen without undergoing a co‐stimulatory signal from an APC A. becomes inactivated. B. can become a helper cell but not a killer cell. C. can get a co‐stimulatory signal from a different APC D. dies. E. divides but doesn't make effector molecules.
A. becomes inactivated.
26. T cells recognize epitopes they have never before encountered by A. randomly generating enormous numbers of TCRs prior to antigenic encounter. B. sampling the environment using phagocytosis and pinocytosis. C. synthesizing immunoglobulins specific for a wide variety of epitopes. D. selecting widely expressed molecules as TCR ligands. E. using germline encoded pattern recognition receptors.
A. randomly generating enormous numbers of TCRs prior to antigenic encounter.
39. Differentiation of Th2 cells from naive precursor cells is dependent on which of the following? A. Toll‐like receptor (TLR) ligands B. T‐bet C. Interleukin‐12 D. GATA‐3 E. Interferon‐D
D. GATA‐3
49. Which of the following mechanisms contributes to the change from B cell production of membrane Ig to secreted Ig? A. V(D)J recombinase‐mediated deletion of the exon encoding the transmembrane domain B. Alternative processing of primary RNA transcripts to remove the transmembrane domain and include a secretory tail piece C. Increased vesicular exocytosis of intracellular stores of the secretory form of Ig D. Switch recombinase‐mediated recombination of the heavy chain locus to juxtapose the V(D)J segment with the exon encoding a secretory tail piece E. Up‐regulation of ecto‐enzymes that proteolytically cleave membrane Ig heavy chains just proximal to the membrane
B. Alternative processing of primary RNA transcripts to remove the transmembrane domain and include a secretory tail piece
5. In humans, MHC class II molecules are expressed by A. all nucleated cells. B. B cells, dendritic cells, and macrophages. C. erythrocytes. D. mast cells. E. naïve T cells.
B. B cells, dendritic cells, and macrophages.
56. The symptoms of Toxic Shock Syndrome result from excessive activation of: A. B‐cells B. CD4+ T cells C. CD8+ T cells D. dendritic cells E. plasma cells
B. CD4+ T cells
44. A 5‐year‐old boy has a history of recurrent pneumococcal pneumonia, Pneumocystis carinii pneumonia (PCP), and bacterial ear infections. His maternal uncle and an older brother experienced the same symptoms, but he has an older sister who is healthy. Laboratory studies indicate normal numbers of B cells and T cells, and the serum contains mostly IgM and very little IgG. If this patient did have a sister affected with the same condition, which of the following genes would most likely contain a mutation? A. AID (activation‐induced deaminase) B. CD40 C. CD40L D. CD28 E. CTLA‐4
B. CD40
51. Which one of the following molecules is important for the production of IgE antibodies? A. CD28 B. CD40 C. IFN‐J D. IL‐2 E. TGF‐E
B. CD40
7. Membrane events required for Th activation include all of the following EXCEPT binding of: A. CD4 to APC Class II MHC. B. CTLA‐4 to APC B7. C. IL‐2Rαβγ to IL‐2. D. LFA‐1 to APC ICAM. E. TCR to peptide on APC Class II MHC.
B. CTLA‐4 to APC B7.
29. A B‐cell is able to make cell‐surface and secreted versions of antibody using: A. Different gene pools. B. Differential splicing. C. Different heavy chain class but the same light chain. D. Different light chain class but the same heavy chain. E. F(ab')2 fragments.
B. Differential splicing.
27. The mechanism of receptor blockade will contribute most importantly to maintaining self‐tolerance to: A. CD3 B. HLA‐DR C. albumin D. Fc receptors E. IgE heavy chains
B. HLA‐DR
2. Apoptosis is physiological cell death genetically encoded and regulated. The main pathways of extrinsic apoptosis (mediated by cytotoxic cells) are receptor‐mediated and granule exocytosis‐ mediated apoptosis. How are these different? A. NK cells use granule mediated, whereas cytotoxic T cells use receptor mediated B. Receptor mediated apoptosis requires susceptibility by the target cell, whereas any cell is a target of granule mediated apoptosis C. Receptor mediated apoptosis is used against cancer cells, whereas virus infected cells are killed by granule mediated apoptosis D. Receptor mediated apoptosis is the primary mechanism, whereas granule‐mediated is the secondary mechanism based on preformed antibodies
B. Receptor mediated apoptosis requires susceptibility by the target cell, whereas any cell is a target of granule mediated apoptosis
Immunological memory is important for an effective vaccine. Which one of the following sentences describes the underlying mechanisms for this most accurately? A. Macrophages and B cells have developed optimal effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond faster and more effectively B. T ‐and B‐cells have developed effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond fast and effectively to prevent disease C. T ‐and B‐cells have developed effector mechanisms towards a certain virus or bacteria and can prevent us from infection D. NK cells, T ‐and B‐cells have developed effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond faster and more effectively
B. T ‐and B‐cells have developed effector mechanisms towards the antigen contained in the vaccine and can during an infection with this antigen respond fast and effectively to prevent disease
25. In contrast to B‐2 B cells, B‐1 B cells A. appear later in development. B. function in innate‐related immune responses. C. express more lgD than lgM on their cell surfaces. D. have a more extensive antigen recognition repertoire. E. require interaction with T cells for their activation.
B. function in innate‐related immune responses.
15. The DNA for an H chain in a B cell making IgG2 antibody for diphtheria toxoid has the following structure: 5'‐V17D5J2‐‐‐Cgamma2‐Cgamma4‐CE‐Calpha2‐3'. How many individual rearrangements were required to go from the embryonic DNA to this B‐cell DNA? A. 1 B. 2 C. 3 D. 4 E. 5
C. 3
6. The IL‐2 receptor occurs in three forms that exhibit different affinities for IL‐2. These include the low affinity monomeric IL‐2Rα (also known as CD25), the intermediate affinity dimeric IL‐2Rβγ, and the high‐affinity trimeric IL‐2Rαβγ. Which cells typically express the high‐affinity trimeric IL‐ 2Rαβγ? A. Resting CD4+ T cells and Ag‐activated CD8+ T cells B. Ag‐activated B cells and Ag‐activated CD4+ T cells C. Ag‐activated CD4+ and Ag‐activated CD8+ T cells D. Naïve B cells and Ag‐activated CD4+ T cells E. Resting CD8+ T cells and Ag‐activated CD4+ T cells
C. Ag‐activated CD4+ and Ag‐activated CD8+ T cells
57. Allelic exclusion is a process that is unique to B‐ and T‐cells. Why is it important for B‐cells to exert (have) allelic exclusion? A. Allelic exclusion ensures that a B cell can recognize only one antigen and give increased antibody diversity B. Allelic exclusion ensures that a B cell can recognize several antigens and give increased antibody diversity C. Allelic exclusion ensures that a B cell can recognize only one antigen and enables control of antibody specificity D. Allelic exclusion ensures that a B cell can produce high affinity antibodies towards several antigens
C. Allelic exclusion ensures that a B cell can recognize only one antigen and enables control of antibody specificity
3. Cross‐presentation is a feature found only in dendritic cells. What is the sequence of events? A. Antigen/microbe/cell is phagocytosed, degraded in lysosomes, loaded onto MHC class II and transported to the surface B. Antigen is translated to protein from phagocytosed microbial mRNA in the cystosol, transported into ER, loaded onto MHC class I and transported to the surface C. Antigen/microbe/cell is phagocytosed and broken down in lysosomes, antigens are transported to cytosol for proteosomal degradation, transported to ER, loaded onto MHC class I and transported to the surface D. Antigen/microbe/cell is phagocytosed, transported to ER, degraded by proteasomes, loaded onto MHC class I, and transported to the surface E. Antigen/microbe/cell is phagocytosed, degraded in lysosomes, loaded onto MHC class I and transported to the surface
C. Antigen/microbe/cell is phagocytosed and broken down in lysosomes, antigens are transported to cytosol for proteosomal degradation, transported to ER, loaded onto MHC class I and transported to the surface
12. Which of the following molecules is expressed on the surface of mature CD4+ T cells? A. B‐cell receptor B. CD1d C. CD3 D. CD8 E. CD19
C. CD3
4. Members of the immunoglobulin superfamily are mainly molecules with a receptor function. Which of the following molecules have the MHC II as its natural ligand? A. CD2 B. CD3 C. CD4 D. TCRαβ E. CD28
C. CD4
34. Which of the following cells have been implicated in the prevention of autoimmune responses (e.g., inflammatory bowel disease) and in the prevention of some nonself responses? A. Antigen‐presenting cells B. Anergized T cells C. CD4+CD25+ Treg cells D. Follicular dendritic cells E. Naïve T cells
C. CD4+CD25+ Treg cells
43. A 5‐year‐old boy has a history of recurrent pneumococcal pneumonia, Pneumocystis carinii pneumonia (PCP), and bacterial ear infections. His maternal uncle and an older brother experienced the same symptoms, but he has an older sister who is healthy. Laboratory studies indicate normal numbers of B cells and T cells, and the serum contains mostly IgM and very little IgG. Which of the following genes most likely contains a mutation in this patient? A. AID (activation‐induced deaminase) B. CD40 C. CD40L D. CD28 E. CTLA‐4
C. CD40L
31. Upon encountering an appropriate peptide‐MHC I on an infected cell, A. B‐cell receptors become cross‐linked and signaling ensues. B. CD4+ cells release IL‐4. C. CD8+ cytotoxic T cells destroy the infected cell. D. naïve Th1 cells secrete cytokines. E. Th0 cells differentiate into Th2 cells.
C. CD8+ cytotoxic T cells destroy the infected cell.
5. Immune responses in the adaptive immune system have to be turned on, and off again when the adequate reaction is fulfilled. Which statement below is correct? A. CTLA‐4 is expressed on activated B‐cells B. CTLA‐4 gives a negative signals to B‐cells C. CTLA‐4 on T‐cells competes with CD28 for binding to B7 on B‐cells D. CTLA‐4 gives an activation signal to T helper cells
C. CTLA‐4 on T‐cells competes with CD28 for binding to B7 on B‐cells
28. Fragments of a cytoplasmic pathogen are presented to T cells by A. direct engagement of cell surface pattern recognition receptors. B. macropinocytosis into JG T cells. C. MHC class I molecules to CD8+ T cells. D. phagocytosis and presentation to CD4+ T cells. E. placement into endocytic vesicles or complexing with class II MHC
C. MHC class I molecules to CD8+ T cells.
10. T‐cell receptors, when co‐expressed with CD8 molecules, are restricted to recognizing and binding peptide fragments associated with A. CD3 molecules. B. CD4 molecules. C. MHC class I molecules. D. MHC class II molecules. E. MHC class Ill molecules.
C. MHC class I molecules.
47. Which one of the following statements accurately describes antigen recognition events in a lymph node during a helper T cell-dependent antibody response to a protein antigen? A. Naive B cells and naive T cells simultaneously recognize the intact protein antigen. B. Naive B cells recognize intact proteins, generate peptide fragments of these proteins, and present them in complexes with major histocompatibility complex (MHC) molecules to naive helper T cells. C. Naive B cells recognize intact proteins, generate peptide fragments of these proteins, and present them in complexes with MHC molecules to differentiated helper T cells. D. Naive T cells recognize peptides bound to MHC molecules presented by dendritic cells, and naive B cells recognize the intact protein antigen bound to the surface of follicular dendritic cells. E. Differentiated helper T cells recognize peptides bound to MHC molecules on dendritic cells, and the T cells secrete cytokines that promote antibody production by any nearby B cells that have recognized different protein antigens.
C. Naive B cells recognize intact proteins, generate peptide fragments of these proteins, and present them in complexes with MHC molecules to differentiated helper T cells.
26. Which of the following statements is incorrect? A. Antibodies in a secondary immune response generally have a higher affinity for antigen than antibodies formed in a primary response. B. Somatic hypermutation of variable‐region genes may con‐ tribute to changes in antibody affinity observed du ring secondary responses. C. Synthesis of antibody in a primary response to a thymus‐dependent antigen occurs predominantly in the blood. D. lsotype switching occurs in the presence of antigen. E. Predominantly lgM antibody is produced in the primary response.
C. Synthesis of antibody in a primary response to a thymus‐dependent antigen occurs predominantly in the blood.
12. In addition to the well‐established Th1 and Th2 subsets recently so‐called Th17 cells were described. Which cytokines are being released in high amounts by these subsets? A. Th1: Interferon‐alpha, Th2: IL‐15, Th17: IL‐17 B. Th1: IL‐1, Th2: IL‐2, Th17: IL‐17 C. Th1: Interferon‐gamma, Th2: IL‐4, Th17: IL‐22 D. Th1: IL‐12, Th2: IL‐4, Th17: IL‐17 E. Th1: TNF‐alpha, Th2: IL‐6, Th17: IL‐22
C. Th1: Interferon‐gamma, Th2: IL‐4, Th17: IL‐22
14. Recognition by T cells is a very important tool for any response to a certain antigen. How does the T cell recognize antigen? A. The T cell recognizes antigen via pattern recognition receptors. B. The T cell recognizes antigen via the T cell receptor for antigen (TCR), whereby for every antigen there is already a specific receptor coded at the level of DNA. C. The T cell recognizes antigen via the T cell receptor for antigen (TCR), which has a high diversity generated at the level of DNA. D. The T cell receptor recognizes antigens via binding to membrane‐bound IgD antibodies. E. The T cell receptor recognizes antigens via the CD3 structure
C. The T cell recognizes antigen via the T cell receptor for antigen (TCR), which has a high diversity generated at the level of DNA.
22. Which of the following statements regarding a B cell expressing both lgM and lgD on its membrane is incorrect? A. The light chains of the IgM and IgD have identical amino acid sequences. B. The constant parts of the heavy chains of the IgM and IgD have different amino acid sequences. C. The lgM and IgD have different antigenic specificities. D. If it is triggered by antigen and T‐cell signals to proliferate and differentiate, it may differentiate into a plasma cell that may secrete IgG, IgE, or IgA antibodies.
C. The lgM and IgD have different antigenic specificities.
33. A state of T‐lymphocyte nonresponsiveness that occurs following peptide‐MHC engagement is known as A. allergy. B. apoptosis. C. anergy. D. autoimmunity. E. hypersensitivity.
C. anergy.
27. Which of the following naïve cells load peptide fragments into MHC class II molecules? A. CD4+ T cells B. CD8+ T cells C. dendritic cells D. JG T cells E. neutrophils
C. dendritic cells
23. NKT cells A. are usually CD8 single positive cells. B. bind epitopes presented by MHC class II molecules. C. express TCRs generated by DNA rearrangement and junctional diversity. D. recognize carbohydrates and complex proteins. E. synthesize immunoglobulin and display it on their cell surfaces.
C. express TCRs generated by DNA rearrangement and junctional diversity.
24. Pre‐pro‐B cells A. contain either N or O light chains. B. demonstrate surface expression of pseudo‐lgM. C. express lg-alpha and lg-beta BCR accessory molecules. D. have VDJ joining of genes. E. express surrogate light chains.
C. express lg-alpha and lg-beta BCR accessory molecules.
17. The antigen specificity of a particular B cell: A. is induced by interaction with antigen B. is determined only by the VL sequence C. is determined by VH and VL region sequences D. changes after isotype switching E. is determined by the CH region
C. is determined by VH and VL region sequences
15. In a patient who later developed an allergy to a certain antigen, the initial response to the antigen consisted of immunoglobulin of the lgM class. However, over time, antigen‐specific lgE came to be predominant. This change from an lgM to an lgE response is caused by A. A affinity maturation. B. allelic exclusion. C. isotype switching. D. junctional diversity. E. somatic hypermutation.
C. isotype switching.
3. The constant regions of the five major types of heavy chains of immunoglobulin molecules dictate the molecule's A. epitope. B. Fab fragment. C. C. isotype. D. tyrosine activation motif. E. variable domain.
C. isotype.
32. Activation of an individual naïve B cell involves binding of membrane‐associated epitopes leading to A. dendritic cell presentation of MHC class I. B. recognition of different epitopes by surface lgD and lgM. C. signaling from the B‐cell receptor. D. the isotype switch. E. ubiquitination and destruction of antigen by proteasomes.
C. signaling from the B‐cell receptor.
11. Eosinophilia in allergic diseases such as allergic rhinitis or asthma is driven by allergen activated Th2 cells. Which cytokine is the most critical cytokine mediating increased eosinophils differentiation, activation and survival? A. IL‐4 B. IL‐13 C. IFN‐gamma D. IL‐5 E. Eotaxin
D. IL‐5
13. Immunocompetent T lymphocytes are selected in the thymus. What is the fate of the T cells that have a high affinity for self‐MHC? A. Clonal expansion and migration to the peripheral lymph nodes B. Clonal anergy C. Migration to the peripheral lymphoid organs where they go into apoptosis D. Deletion in the thymus via induction of apoptosis E. Homing to the bone marrow as part of a feedback loop
D. Deletion in the thymus via induction of apoptosis
30. The cytoplasmic region of surface IgM consists of: A. A single H chain constant region domain. B. A light chain. C. 110 amino acids. D. 3 amino acids. E. Carbohydrate.
D. 3 amino acids.
54. Which of the following antigenic structures might activate B cell antibody production without the aid of T cells? A. Lysozyme B. Benzene C. Glucose‐6‐phosphate D. ABO blood group antigen E. Rh factor antigen
D. ABO blood group antigen
36. Foxp3 nuclear transcription factor is expressed within A. B cells. B. CD4+CD8+ (double positive) thymocytes. C. CD8+ cytotoxic cells. D. CD4+CD25+ T regulatory cells. E. Th2 cells.
D. CD4+CD25+ T regulatory cells.
46. The initial cellular events that are induced by antigen‐mediated cross‐linking of the B cell receptor (BCR) complex include all of the following EXCEPT: A. Increased percentage of time spent in mitosis, resulting in rapid proliferation B. Increased expression of B7, resulting in enhanced APC function C. Increased expression of bcl‐2, resulting in improved survival D. Increased expression of CCR7, promoting migration into lymph node follicles E. Increased expression of the interleukin‐2 receptor, resulting in enhanced proliferation and response to T cell signals
D. Increased expression of CCR7, promoting migration into lymph node follicles
35. Which of the following cells require interaction with both peptide‐MHC (signal 1) and a set of costimulatory second signals (signal 2) from a Ag‐loaded mature dendritic cell to become activated? A. Anergized T cells B. B cells C. Mast cells D. Naïve T cells E. Natural killer cells
D. Naïve T cells
9. Following cytokine binding to a specific cell‐surface receptor, a lymphocyte is stimulated to undergo signaling via the JAK‐STAT pathway. In this pathway, which of the following will be induced to translocate to the cell's nucleus to regulate transcription? A. JAK B. Ras C. SH2‐containing adapter proteins D. STAT dimers E. tyrosine kinase
D. STAT dimers
30. CD4+ T cells that respond to intracellular pathogens by recruiting and activating phagocytic cells are termed A. antigen‐presenting cells. B. cytotoxic T lymphocytes. C. Th0 cells. D. Th1 cells. E. Th2 cells.
D. Th1 cells
20. Which of the following statements concerning the organization of lg genes is correct? A. V and J regions of embryonic DNA have already undergone a rearrangement. B. Light‐chain genes undergo further rearrangement after surface IgM is expressed. C. VH gene segments can rearrange with JN or JO gene segments. D. The VDJ segments coding for an Ig VH region may associate with different heavy‐chain constant‐region genes. E. After VDJ joining has occurred, a further rearrangement is required to bring the VDJ unit next to the CP gene.
D. The VDJ segments coding for an Ig VH region may associate with different heavy‐chain constant‐region genes.
50. Which of the following statements about Ig isotype switching is NOT true? A. Interleukin‐4 promotes switching to the IgE isotype by increasing germline transcription of the CH exon. B. Isotype switching involves recombination of a V(D)J complex with downstream C region genes and the deletion of intervening DNA including other C region genes. C. Activation‐induced deaminase (AID) is required for switch recombination. D. The enzymes that mediate isotype switching recognize conserved heptamer and nonamer DNA sequences adjacent to the constant region exons. E. The same recombined V(D)J gene complex is used to encode the antigen‐binding region of the antibodies produced by a B cell before and after isotype switching.
D. The enzymes that mediate isotype switching recognize conserved heptamer and nonamer DNA sequences adjacent to the constant region exons.
42. A 5‐year‐old boy has a history of recurrent pneumococcal pneumonia, Pneumocystis carinii pneumonia (PCP), and bacterial ear infections. His maternal uncle and an older brother experienced the same symptoms, but he has an older sister who is healthy. Laboratory studies indicate normal numbers of B cells and T cells, and the serum contains mostly IgM and very little IgG. Which of the following abnormalities would NOT be likely in this patient? A. The IgG antibodies that are present are of lower affinity for antigen than of those of a healthy individual. B. Lymph nodes are without well‐developed follicles containing germinal centers. C. Macrophage killing of intracellular microbes is impaired. D. There is limited diversity in the repertoire of IgM antibodies produced. E. There is no evidence of somatic mutation of IgM variable regions.
D. There is limited diversity in the repertoire of IgM antibodies produced.
19. The ability of a single B cell to express both lgM and IgD molecules on its surface at the same time is made possible by: A. allelic exclusion B. isotype switching C. simultaneous recognition of two distinct antigens D. alternative RNA splicing E. use of genes from both parental chromosomes
D. alternative RNA splicing
Epitope‐specific receptors of T lymphocytes are found A. as either cytosolic or membrane‐bound proteins. B. in blood plasma, lymph, and other secretory fluids. C. on the surface of plasma cells. C. as transmembrane polypeptides. D. in the nuclear lipid bilayer.
D. in the nuclear lipid bilayer.
8. Cytoplasmic signals generated in response to antigen binding and co‐stimulatory signals to CD8+ T cells include all of the following EXCEPT: A. activation of transcription factors that upregulate synthesis of IL‐2. B. aggregation of TCR and CD8 in the T cell membrane. C. increased free intracellular Ca++. D. induction of RAG synthesis. E. tyrosine kinase binding to the cytoplasmic domains of CD3 and CD8.
D. induction of RAG synthesis
21. Which of the following does not contribute to the antigen‐binding site diversity of B‐cell antigen receptors? A. multiple V genes in the germline B. random assortment of L and H chains C. imprecise recombination of V and J or V, D, and J segments D. inheritance of multiple C‐region genes E. somatic hypermutation
D. inheritance of multiple C‐region genes
18. If you could analyze at the molecular level a plasma cell making lgA antibody, you would find all of the following except : A. DNA sequence for V, D, and J genes translocated near the CD DNA exon B. mRNA specific for either N or O light chains C. mRNA specific for J chains D. mRNA specific for P chains E. DNA sequence coding for the T‐cell receptor for antigen
D. mRNA specific for P chains
22. JG T cells A. contain very extensive antigen recognition repertoires. B. express surface markers that are also characteristic of NK cells. C. generate memory when recognizing antigen on multiple occasions. D. migrate preferentially to respiratory or organs, skin, and peritoneal cavity. E. respond more slowly to antigen than do alpha/beta T cells.
D. migrate preferentially to respiratory or organs, skin, and peritoneal cavity.
11. B lymphocytes synthesize and express immunoglobulin A. containing multiple epitope specificities. B. in cytoplasmic phagosomes. C. in membrane complexes also containing CD3. D. on their cell membrane surface. E. only after leaving the bone marrow.
D. on their cell membrane surface.
14. The white pulp of the spleen is enriched in A. erythrocytes carrying hemoglobin. B. CD4+CD8+ T cells binding to MHC. C. NK cells recognizing targets. D. plasma cells secreting immunoglobulin. E. precursor cells developing into mature B cells.
D. plasma cells secreting immunoglobulin.
23. Which of the following plays a role in changing the antigen binding site of a B cell after antigenic stimulation? A. junctional diversity B. combinatorial diversity C. germline diversity D. somatic hypermutation E. differential splicing of primary RNA transcripts
D. somatic hypermutation
45. The B cell receptor (BCR) complex and the signaling cascades to which it is linked share many similarities with the T cell receptor (TCR) complex and its linked signaling cascades. Which of the following comparisons between BCR and TCR signaling is NOT true? A. There are ITAMs in the cytoplasmic tails of CD3 in the TCR complex and in the cytoplasmic tails of IgD and IgE in the BCR complex. B. The cytoplasmic tails of membrane Ig and TCR antigen receptors are very short and lack intrinsic signaling functionality. C. Early signaling events induced by antigen binding to both BCR and TCR involve both Src family and Zap‐70 family protein tyrosine kinases. D. Phospholipase C-mediated generation of IP3 and DAG occurs downstream of both BCR and TCR signaling. E. CD4/CD8 coreceptors in T cells and the CR2 coreceptor in B cells both enhance responses to antigen by a PI3 kinase-dependent mechanism.
E. CD4/CD8 coreceptors in T cells and the CR2 coreceptor in B cells both enhance responses to antigen by a PI3 kinase-dependent mechanism.
48. Which one of the following B cell responses is NOT stimulated by CD40 ligand? A. Association of TRAFs with the cytoplasmic tails of CD40 molecules B. Activation of NF‐NB C. Enhanced expression of B7‐1 and B7‐2 D. Enhanced Ig isotype switch recombinase activity E. Enhanced production of membrane Ig
E. Enhanced production of membrane Ig
52. Which of the following events does NOT occur within germinal centers? A. Somatic mutation of Ig V genes B. Generation of memory B cells C. B cell proliferation D. Affinity maturation E. Ig gene V(D)J recombination
E. Ig gene V(D)J recombination
28. The first immunoglobulin heavy chain class to be expressed on the surface of a newly produced B‐cell is: A. IgA B. IgD C. IgE D. IgG E. IgM
E. IgM
40. The mechanisms by which TH1 cells protect against microbes include all of the following EXCEPT: A. Secretion of IFN‐J which activates microbicidal functions of macrophages B. Expression of CD40 ligand, which binds to CD40 on macrophages and activates them C. Secretion of IFN‐J which promotes B cell production of opsonizing antibodies D. Secretion of TNF which enhance neutrophil killing of ingested microbes E. Release of granzyme B, which stimulates apoptosis of bacteria
E. Release of granzyme B, which stimulates apoptosis of bacteria
38. Which of the following comparisons between Th1 and Th2 cells is true? A. Th1 cells produce IL‐1 but not IL‐2, and Th2 cells produce IL‐2 but not IL‐1. B. Th1 cells are class I MHC restricted, and Th2 cells are class II MHC restricted. C. The chemokine receptors CXCR3 and CCR5 are more highly expressed on Th2 cells than on Th1 cells. D. Th2 cells are more likely to bind to E‐selectin and P‐selectin on endothelial cells than are Th1 cells. E. Th1 cells produce IFN‐gamma but not IL‐4, and Th2 cells produce IL‐4 but not IFN‐gamma
E. Th1 cells produce IFN‐gamma but not IL‐4, and Th2 cells produce IL‐4 but not IFN‐gamma
25. Which of the following is expressed on the surface of the mature B lymphocyte? A. CD40 B. MHC class II molecules C. CD19 D. IgM and Ig D E. all of the above
E. all of the above
37. In activated T cells, CD152 (CTLA4) A. becomes sequestered within the Golgi. B. binds to the appropriate surface peptide‐MHC. C. induces progression through the cell cycle. D. stimulates transcription of IL‐2 mRNA. E. begins to move to the membrane and bind CD80/86.
E. begins to move to the membrane and bind CD80/86.
19. When a memory B cell is restimulated by its specific antigen, small point mutations that accumulate in the DNA encoding variable regions of both light and heavy chains may result in A. antigen‐stimulated VDJ joining and new antigen specificity. B. change from production of lgM to lgG. C. DNA chromosomal rearrangement and altered antigen specificity. D. inactivation of either the maternal or paternal VL and VH allele. E. generation of antibody with increased binding affinity for its epitope.
E. generation of antibody with increased binding affinity for its epitope.
24. The earliest stages of B‐cell differentiation: A. occur in the embryonic thymus B. require the presence of antigen C. involve rearrangement of N‐chain gene segments D. involve rearrangement of surrogate light‐chain gene segments E. involve rearrangement of heavy‐chain gene segments
E. involve rearrangement of heavy‐chain gene segments
4. When an immunoglobulin molecule is subjected to cleavage by pepsin, the product(s) A. are individual heavy and light chains. B. can no longer bind to antigen. C. consist of two separated antigen‐binding fragments. D. crystallize during storage in the cold. E. is a dimeric antigen‐binding molecule.
E. is a dimeric antigen‐binding molecule.
20. T cell precursors, known as prothymocytes, migrate from the bone marrow to the thymus in response to A. eotactin. B. IL‐4. C. IL‐5. D. IL‐10. E. lymphotactin.
E. lymphotactin.
16. If you had 50 V, 20 D, and 6 J regions able to code for a heavy chain and 40 V and 5 J‐region genes able to code for a light chain, you could have a maximum repertoire of: A. 76 +45 = 121 antibody specificities B. 76 x 45 = 3420 specificities C. (40 x 5) + (50 x 20 x 6) = 6200 specificities D. (40 x 5) x (50 x 20 x 6) = 1,200,000 specificities E. more than 1,200,000 specificities
E. more than 1,200,000 specificities
13. Positive selection refers to A. the ability of single positive cells to bind both MHC class I and II. B. cortical thymocytes' acquisition of TCR. C. migration of stem cells to the thymus to become T cells. D. programmed cell death of single positive T cells. E. recognition of MHC by CD4+CD8+ thymocytes.
E. recognition of MHC by CD4+CD8+ thymocytes.
7. Migration of a B lymphocyte to specific sites (such as a lymph node) is dependent in part on the use of A. antibodies. B. CD8. C. CD3. D. complement. E. selectins.
E. selectins.
2. Antibodies (immunoglobulins) A. are synthesized and secreted by both B and T cells. B. bind to several different epitopes simultaneously. C. contain four different light chain polypeptides. D. recognize specific epitopes together with self‐molecules. E. tag antigens for destruction and removal.
E. tag antigens for destruction and removal.
29. The term immunologic synapse refers to A. PAMP recognition by pattern recognition receptors. B. restriction of CD4+ T cells to MHC class I. C. selective unresponsiveness of T cells. D. T cell recognition of soluble molecules. E. the interface between antigen‐presenting cells and T cells.
E. the interface between antigen‐presenting cells and T cells.
