MCB408FA22_Exam2_FormAKey (1)

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MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 1 1. You have isolated B cells from a mouse infected with murine cyclomegavirus (mCMV). You sort the cells to identify the population that can bind mCMV antigens and then sequence the genes encoding the BCR light chain and heavy chain variable domains in each cell. The sequencing results suggest that within this cell population, a single heavy chain variable domain sequence has been paired with multiple different light chain variable domain sequences. Is this possible and why/why not? A. Yes, combinatorial diversity ensures that identical copies of heavy chains can be paired with multiple, different light chains on a single B cell. B. No, allelic exclusion ensures that identical heavy chains can be expressed on multiple B cells and that they are always paired with the same light chain on each of those cells. C. No, somatic hypermutation ensures that all B cells in one animal (e.g. this mouse) each express a unique BCR. D. Yes, combinatorial diversity ensures that identical copies of the same heavy chain can be expressed on multiple B cells and can be paired with a different light chain on each of those cells. E. Yes, class-switch recombination is a process in which identical heavy chains can be paired with different light chains. 2. During V(D)J recombination, the spacing between RSS heptamer and nonamer sequences: A. ensures that the coding sequence for the same type of segment (e.g. two V segments) are able to recombine B. is not absolute and can vary by 1-2 bases C. provide binding sites for Terminal deoxynucleotidyl transferase (TdT) D. are not found in genes encoding TCR V, D, and J segments E. ensures that the coding sequence for the same type of segment (e.g. two V segments) are NOT able to recombine 3. A plasma cell secreting IgG1 undergoes class-switch recombination and subsequently secretes dimeric IgA. Which of the following Fc receptors do you expect to transcytose dimeric IgA to the mucosal secretions in the gut lumen? A. Fc g RIIB B. Fc e RI C. Polymeric Ig Receptor (pIgR) D. The Neonatal Fc receptor FcRN E. None of the above

MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 2 4. You are studying BCR somatic hypermutation and affinity maturation. Your experiments require you to find cells that are actively utilizing activation-induced cytidine deaminase (AID) to mediate this process. Of the following locations, where would you expect to find the majority of these cells? A. A germinal center light zone B. The thymus C. A germinal center dark zone D. The lymph node paracortex E. AID does not mediate BCR somatic hypermutation and affinity maturation 5. True or false: One example of antibody mediated effector functions is agglutination, or cross- linking, of antigens. A. True B. False 6. Which of the following factors plays a direct role in both CTL engagement of target cells and lymphocyte extravasation? A. LFA-1 B. RAG-1/2 C. CD21 D. ILC-1 E. CD4 7. Of the MHC components listed below, which contains the majority of polymorphic amino acids arising from allelic variation in MHC-Class I encoding genes in the human population? A. β2M B. The α3 domain C. The α-helices of the β1 domain D. MHC class I components are not polymorphic E. The peptide binding groove

MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 3 8. You are studying an αβ TCR, which binds to a peptide loaded in an MHC class I molecule. Your experiments reveal that the addition of non-templated (N) nucleotides during V(D)J recombination resulted in amino acids that directly interact with (bind) the peptide. Choosing from the following list, which of the TCR components is responsible for this interaction? A. CDR2β B. CDR2α C. CDR1α D. CDR3β E. Constant β domain 9. Following protein degradation by a proteasome, peptides destined to be loaded onto MHC class I are transported into a cellular compartment where most stages of MHC class I assembly and peptide loading occurs. Of the following options (1) which protein transports the peptides and (2) in which cellular compartment does MHC class I assembly occur? A. (1) TAP and (2) the endoplasmic reticulum (ER) B. (1) TAP and (2) the early endosome C. (1) ERAP and (2) the endoplasmic reticulum (ER) D. (1) HLA-DM and (2) the GOLGI E. (1) HLA-DM and (2) the endoplasmic reticulum (ER) 10. True or false: Your cells encode a single MHC class I gene and express one unique MHC class I molecule. A. True B. False 11. MHC class I can display endogenous peptides on the cell surface. Peptides loaded onto MHC I molecules require the assistance of chaperones and many other proteins. Which of the following proteins is NOT directly involved in this process? A. ERAP B. CLIP C. ERp57 D. Tapasin E. Calreticulin

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MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 4 12. You are a third-year graduate student investigating a virus that can infect lymphocytes at different stages of development. You isolate a cell that is expressing VpreB and λ5. Of the following, which type of cell have you isolated? A. Pro-B cell B. Mature naive B cell C. Double negative thymocyte D. Pre-B cell E. Memory B cell 13. Immunological synapses can form between T cells and APCs, as well as between T cells and target host cells. Which of the following proteins are not required for successful formation of immunological synapses between CTLs and target host cells? A. CD80/CD86 B. CD8 C. CD3/TCR D. LFA-1 E. MHC class I 14. Of the following, which Fc receptor possesses an immunoreceptor tyrosine-based inhibitory motif? A. Fc ࠵? RI B. FcαRI C. pIgR D. FcRn E. Fc ࠵? RIIB 15. Compared to MHC class I molecules, which of the following statement(s) are true of MHC class II molecules? A. On average, length of the bound peptide contains more amino acids. B. On average, length of the bound peptide contains fewer amino acids. C. C- and N-termini anchor the peptide to the binding groove. D. The peptide binding groove consists of two domains located on the same polypeptide chain. E. None of the above

MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 5 16. A plasma cell expressing IgM undergoes class-switch recombination and subsequently expresses IgG1. Of the following proteins and complexes, which is required for this activity? A. RAG1/2 B. Terminal deoxynucleotidyl transferase (TdT) C. Activation-induced cytidine deaminase (AID) D. ICAM-1 E. None of the above 17. A receptor on a natural killer (NK) cell has bound an MHC class I molecule on another host cell. Which of the following statements describes the most likely outcome of this particular interaction? A. The NK cell receives an activating signal. B. The NK cell receives an inhibitory signal. C. The NK cell will kill the host cell. D. The NK cell will become anergic. E. The NK cell undergoes apoptosis. 18. Which of the following statements about High-endothelial venules (HEVs) is false? A. HEVs are specialized post-capillary venules found in the spleen. B. HEVs are specialized post-capillary venules found in lymph nodes. C. HEV cells express addressins. D. Approximately 30000 lymphocytes can move through the HEVs of a signal lymph node every second. E. HEVs express factors that facilitate lymphocyte extravasation. 19. You are a clinical researcher. A patient has a disease characterized by T cells that bind self- peptides through their TCRs. Which of the following is a plausible explanation for this phenotype? A. Deletion of the RAG1/RAG2 genes B. Mutations in Terminal deoxynucleotidyl transferase (TdT) gene C. Mutations in activation-induced cytidine deaminase (AID) D. Deficiency of memory B cells E. Mutations in the autoimmune regulator (AIRE) gene

MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 6 20. Which cytokine is associated with autocrine signaling during the activation of naïve lymphocytes? A. IL-2 B. IL-7 C. CXCL12 D. INF- g E. IL-10 21. You identify a healthy host cell that is presenting exogenous peptides on MHC class I. Based on this characteristic, which term best describes this cell? A. Anergic APC B. Activated APC C. Any cell in your body D. Licensed APC E. None of the above 22. You are investigating the immune response in the GALT. You identify a population of T cells that are expressing FoxP3 and secreting IL-10. Which T cell subset have you most likely identified? A. T H 1 B. T H 17 C. T REG D. T H 2 E. None of the above 23. Which of the following conditions do you expect to drastically reduce the number of T H effector cells below normal levels? A. HIV-1 infection B. Round worm infection C. Type-1 immune response in the lung D. CD40 binding to CD40L E. Upregulation of INF- g

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MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 7 24. Which of the following T cell subsets do you expect to have the lowest capacity for self- renewal? A. Effector memory T cells B. Central memory T cells C. Stem cell memory T cells D. Resident memory T cells E. Effector T cells 25. A naive T cell has just encountered an APC presenting a peptide on an MHC class II molecule. The T cell binds the APC with its TCR and with CD28. Based on signals resulting from these two interactions, which receptor do you expect this T cell to upregulate as part of its activation and proliferation process? A. IL-10R B. IL-2R C. Fc a RI D. TLR4 E. None of the above 26. Which of the following statements best describes a common outcome of perforin and granzyme B mediated functions? A. Naive T cell activation B. Host cell caspase activation and subsequent apoptosis C. Neutrophil activation D. Induction of cross-presentation E. None of the above 27. A double positive (DP) thymocyte binds an MHC class I molecule on a cortical thymic epithelial cell (TECs); the interaction is characterized by intermediate binding affinity. Which of the following processes is likely to happen next? The thymocyte: A. becomes a single, CD4+, positive cell and moves into the thymic medulla. B. remains DP and moves into the thymic medulla. C. dies through "death by neglect". D. becomes a single, CD8+, positive cell and moves into the thymic medulla. E. becomes a single, CD4+, positive cell and moves into secondary lymphoid tissues.

MCB 408 Exam 2 Fall 2022 Professor Beth Stadtmueller 8 28. You are investigating an emerging virus that infects humans and you have identified "protein X" as a virulence factor. Through experiments you determine that protein X is a superantigen. Based on this finding, what do you expect will happen when you combine purified protein X with naive T-cells and dendritic cells in a single culture flask? A. The T cells will become activated. B. The T cells will undergo apoptosis. C. The dendritic cell will undergo apoptosis. D. No change compared to control experiments lacking protein X. E. The dendritic cell and T cell will not form contacts with each other. 29. Which of the following statements does NOT describe a property or activity associated with RAG1/2 recombinase function? A. DNA binding B. Addition of palindromic ‘P’ nucleotides between V and J segments C. DNA cleavage D. Histone binding E. Expression only in lymphocytes 30. Which of the following protein complexes transduces TCR activation signals to the cell interior? A. LFA-1 B. CD2 C. CD4 D. CD3 E. IgaIgb END OF EXAM

MCB408FA22_Exam2_FormAKey (1)

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