front 1 1. What is the clonal selection theory? A. Each T cell bears multiple types of antigen receptors B. Each B cell bears a single type of Ig receptor and forms identical clones after activation C. All B cells recognize the same antigen D. Plasma cells have many different receptors | back 1 B. Each B cell bears a single type of Ig receptor and forms identical clones after activation |
front 2 2. Why is the clonal selection theory relevant? A. Explains innate immunity B. Explains why antibodies are nonspecific C. Explains the formation of memory cells for faster secondary responses D. Describes antigen presentation | back 2 C. Explains the formation of memory cells for faster secondary responses |
front 3 3. What is a plasma cell? A. A B cell that secretes cytokines B. A B cell that secretes antibodies C. A naïve B cell in bone marrow D. A macrophage in the spleen | back 3 B. A B cell that secretes antibodies |
front 4 4. Which mature B cell type participates in germinal center reactions and shows somatic hypermutation? A. B1 cell B. MZB cell C. B2 cell D. Plasma cell | back 4 B. MZB cell |
front 5 5. Which chemokines recruit B cells to secondary lymphoid tissues? A. IL-4 and IL-5 B. CCL19 and CCL21 C. TNF and IL-1 D. CXCL10 and CXCL11 | back 5 B. CCL19 and CCL21 |
front 6 6. Which structure secretes CXCL13 and holds antigen like flypaper? A. Dendritic cell B. Follicular dendritic cell (FDC) C. Plasma cell D. B1 cell | back 6 B. Follicular dendritic cell (FDC) |
front 7 7. What is BAFF and its role? A. B-cell activating factor; promotes B cell activation and survival B. A cytokine that inhibits T cell activity C. A surface receptor on macrophages D. A transcription factor in plasma cells | back 7 A. B-cell activating factor; promotes B cell activation and survival |
front 8 8. What is the Fibroblastic Reticular Cell Conduit (FRCC) system? A. Antibody transport system B. Channel that allows small antigens to flow through lymph node C. Site of macrophage development D. Cytokine signaling pathway | back 8 B. Channel that allows small antigens to flow through lymph node |
front 9 9. Which of the following describes a lipid raft? A. Soluble protein cluster in cytoplasm B. Cholesterol- and sphingolipid-rich membrane region involved in signaling C. Cytoskeletal filament D. Vesicle carrying MHC molecules | back 9 B. Cholesterol- and sphingolipid-rich membrane region involved in signaling |
front 10 10. What is the role of Igα/Igβ in BCR signaling? A. Bind antigen directly B. Anchor the BCR to the membrane C. Transduce the signal through ITAM phosphorylation D. Inhibit the B cell response | back 10 C. Transduce the signal through ITAM phosphorylation |
front 11 11. What are the costimulatory molecules in the B cell response? A. CD3, CD4, CD8 B. CD19, CD21, CD81 C. MHC I, MHC II D. CD28, B7 | back 11 B. CD19, CD21, CD81 |
front 12 12. What are the three cell types required for a good B cell response? A. FDC, B cell, activated CD4+ T cell B. Plasma cell, macrophage, dendritic cell C. NK cell, macrophage, B cell D. Neutrophil, dendritic cell, plasma cell | back 12 A. FDC, B cell, activated CD4+ T cell |
front 13 13. What is a cognate T–B cell interaction? A. Two unrelated cells binding randomly B. A B and T cell that recognize different epitopes C. A B and T cell that recognize the same antigen epitope D. A B cell activating a CD8+ T cell | back 13 C. A B and T cell that recognize the same antigen epitope |
front 14 14. Which interaction is crucial for B cell activation and class switching? A. CD28/B7 B. CD40/CD40L C. MHC I/CD8 D. ICAM/LFA-1 | back 14 B. CD40/CD40L |
front 15 15. What cytokine signal determines the type of isotype produced during class switching? A. IL-10 B. IL-13 C. IFN-γ D. TNF-α | back 15 B. IL-13 |
front 16 16. What enzyme initiates somatic hypermutation and class switch recombination? A. DNA polymerase B. Activation-induced deaminase (AID) C. RNA polymerase D. DNase | back 16 B. Activation-induced deaminase (AID) |
front 17 17. During somatic hypermutation, AID converts what base to what base? A. Adenine → Guanine B. Cytosine → Uracil C. Thymine → Adenine D. Guanine → Cytosine | back 17 B. Cytosine → Uracil |
front 18 18. Which zone of the germinal center is densely packed with proliferating B cells? A. Light zone B. Dark zone C. B cell zone D. T cell zone | back 18 B. Dark zone |
front 19 19. Which statement about T-dependent B cell responses is correct? A. Occurs without T cell help B. Requires T cell recognition of same antigen epitope C. Only produces IgM D. Occurs only in the thymus | back 19 B. Requires T cell recognition of same antigen epitope |
front 20 20. Which type of antigen typically elicits a T-independent B cell response? A. Soluble protein B. Bacterial polysaccharide or cell wall component C. Viral peptide D. Fungal glycoprotein | back 20 B. Bacterial polysaccharide or cell wall component |
front 21 21. Germinal center | back 21 Site of somatic hypermutation and class switching |
front 22 22. FDC | back 22 Holds antigen and secretes CXCL13 |
front 23 23. plasma cell | back 23 Secretes antibody, no longer divides |
front 24 24. plasmablast | back 24 Early antibody-secreting B cell that can still divide |
front 25 25. TFH cell | back 25 Provides help for B cell maturation and class switching |
front 26 26. Describe the role of chemokines (CCL19, CCL21, CXCL13) in B cell migration and activation. | back 26 CCL19/CCL21 recruit B cells to T cell zone via CCR7; CXCL13 attracts B cells into follicles via CXCR5. |
front 27 27. What is the purpose of a B cell acting as an antigen-presenting cell (APC)? | back 27 To present antigen on MHC II to a cognate T cell for activation and class switching |
front 28 28. Define clustering of the BCR and explain what causes it. | back 28 Antigen binding causes BCRs to cluster into lipid rafts, enhancing signaling |
front 29 29. Explain the difference between FDCs and conventional dendritic cells. | back 29 FDCs hold antigen; conventional DCs process and present antigen |
front 30 30. List the three SMAC regions and their purposes. | back 30 cSMAC = signaling; pSMAC = adhesion; dSMAC = actin support |
front 31 31. What happens to a B cell that fails to find its cognate antigen in the lymph node? | back 31 It exits lymph node and reenters circulation. |
front 32 32. Explain the difference between plasma cells and plasmablasts. | back 32 Plasma cells secrete antibody but do not divide; plasmablasts secrete and still divide. |
front 33 33. What two major processes occur in the germinal center? | back 33 Somatic hypermutation (affinity maturation) and class switching. |
front 34 34. Explain how somatic hypermutation improves antibody affinity. | back 34 Introduces mutations in variable region; selects B cells with stronger antigen binding. |
front 35 35. Describe the difference between T-dependent and T-independent B cell responses. | back 35 TD = requires T cell help and class switching; TI = activated by polysaccharide antigens, mostly IgM response. |