front 1 What is the clonal selection theory? | back 1 Each B cell has a unique receptor; when its specific antigen binds, that B cell is selected to proliferate and differentiate into effector and memory cells. |
front 2 Why is clonal selection theory relevant? | back 2 It explains immune specificity (targeting exact antigens) and memory (faster response upon re-exposure). |
front 3 What is a plasma cell? | back 3 A fully differentiated B cell that secretes large amounts of antibodies, has lots of ER/Golgi, and no surface BCR. |
front 4 What are the “ground rules” of immune responses? | back 4 Antigen finding is random, many lymphocytes exist, one antigen has multiple epitopes, multiple responses occur simultaneously. |
front 5 What is the difference between T cells and B cells in antigen recognition? | back 5 T cells require antigen presented on MHC (MHC-restricted), while B cells bind whole antigen directly. |
front 6 Where do immune responses mainly occur? | back 6 Secondary lymphoid organs like lymph nodes and spleen. |
front 7 What are B2 cells? | back 7 Conventional adaptive B cells found in lymph node follicles that respond to specific antigens. |
front 8 What are B1 and marginal zone B cells? | back 8 Innate-like B cells that respond quickly and do not require strong adaptive signals. |
front 9 What are T-dependent (TD) antigens? | back 9 Protein antigens that require T cell help and lead to strong responses with memory and class switching. |
front 10 What are T-independent (TI) antigens? | back 10 Non-protein antigens (often polysaccharides) that activate B cells without T cell help. |
front 11 What are the characteristics of TD responses? | back 11 Germinal center formation, class switching, memory cell formation, high affinity antibodies. |
front 12 What are the characteristics of TI responses? | back 12 Mostly IgM, weak memory, little affinity maturation. |
front 13 What are TI-1 antigens? | back 13 Antigens that activate B cells through TLRs (e.g., LPS). |
front 14 What are TI-2 antigens? | back 14 Highly repetitive antigens that strongly crosslink BCRs. |
front 15 How do antigens reach lymph nodes? | back 15 Through lymphatic vessels from tissues. |
front 16 What is the role of chemokines in B cell recruitment? | back 16 They guide B cells to the correct zones within lymphoid tissues. |
front 17 What are HEVs? | back 17 High endothelial venules where lymphocytes enter lymph nodes from blood. |
front 18 What is BAFF? | back 18 A survival factor that promotes B cell survival. |
front 19 What is the B cell zone? | back 19 The follicle in lymph nodes where B cells reside. |
front 20 What is the FRC network? | back 20 A structural network that guides immune cell movement and distributes chemokines. |
front 21 What is opsonization? | back 21 Tagging pathogens with complement to enhance immune recognition. |
front 22 What receptor do B cells use to bind complement-tagged antigen? | back 22 CD21. |
front 23 How do B cells first encounter antigen? | back 23 Through free antigen, subcapsular macrophages, or follicular dendritic cells. |
front 24 What are subcapsular macrophages? | back 24 Cells that capture antigen and pass it to B cells in lymph nodes. |
front 25 What is the role of complement in B cell activation? | back 25 It enhances antigen binding and strengthens activation. |
front 26 What is BCR clustering? | back 26 Grouping of multiple BCRs when antigen binds, leading to stronger signaling. |
front 27 What causes BCR clustering? | back 27 Repetitive antigens binding multiple BCRs simultaneously. |
front 28 What is a lipid raft? | back 28 Membrane microdomain rich in signaling molecules that enhances BCR signaling. |
front 29 What is the cSMAC? | back 29 Central signaling area containing BCR and antigen. |
front 30 What is the pSMAC? | back 30 Adhesion region that stabilizes the interaction. |
front 31 What is the dSMAC? | back 31 Outer regulatory region controlling the interaction. |
front 32 What is the result of BCR activation? | back 32 B cell activation and antigen internalization. |
front 33 What are the B cell co-receptors? | back 33 CD19, CD21, CD81. |
front 34 What is the function of the co-receptor complex? | back 34 Amplifies BCR signaling. |
front 35 What is the role of Igα | back 35 Igβ? / They transmit signals inside the cell after antigen binds BCR. |
front 36 What are ITAMs? | back 36 Signaling motifs on Igα/Igβ that initiate intracellular signaling. |
front 37 What is the outcome of BCR signaling? | back 37 Proliferation, differentiation, antibody production, and antigen presentation. |
front 38 What are the four B cell differentiation outcomes? | back 38 Plasma cells, plasmablasts, memory B cells, germinal center B cells. |
front 39 What are plasma cells? | back 39 Long-lived antibody-secreting cells with no BCR. |
front 40 What are plasmablasts? | back 40 Short-lived, proliferating early antibody-secreting cells. |
front 41 What are memory B cells? | back 41 Long-lived cells that respond faster and stronger upon re-exposure. |
front 42 What are germinal center B cells? | back 42 B cells undergoing mutation and selection to improve antibody affinity. |
front 43 What is the B cell response timeline? | back 43 Early plasmablasts → germinal center response → memory and long-lived plasma cells. |
front 44 What are the characteristics of plasmablasts? | back 44 Early responders, secrete antibodies, still dividing, short-lived. |
front 45 What is the difference between naïve and plasma B cells? | back 45 Naïve have surface BCR and do not secrete antibodies; plasma cells secrete antibodies and lack BCR. |
front 46 What are intrinsic properties of naïve B cells? | back 46 Circulate, express BCR, ready but inactive. |
front 47 What are intrinsic properties of plasma cells? | back 47 Specialized for antibody production with extensive ER/Golgi. |
front 48 What are inducible properties of naïve B cells? | back 48 Can proliferate and differentiate. |
front 49 What are inducible properties of plasma cells? | back 49 Increased antibody secretion; plasmablasts may still divide. |
front 50 What are germinal centers? | back 50 Sites where B cells improve antibody affinity. |
front 51 What cells are in germinal centers? | back 51 B cells, Tfh cells, and follicular dendritic cells. |
front 52 What are follicular dendritic cells (FDCs)? | back 52 Cells that display intact antigen to B cells for selection. |
front 53 How do FDCs differ from regular dendritic cells? | back 53 They do not process antigen and interact with B cells instead of T cells. |
front 54 What are light zones? | back 54 Areas where B cells are selected based on affinity. |
front 55 What are dark zones? | back 55 Areas where B cells proliferate and undergo mutation. |
front 56 What happens in the light zone? | back 56 Selection and isotype switching. |
front 57 What happens in the dark zone? | back 57 Somatic hypermutation. |
front 58 What are cognate B and T cells? | back 58 Cells that recognize the same antigen. |
front 59 What are Tfh cells? | back 59 T follicular helper cells that help B cells activate and mature. |
front 60 What do Tfh cells control? | back 60 Activation, class switching, affinity maturation, and memory formation. |
front 61 How do B and T cells find each other? | back 61 Chemokine-guided migration to the T–B border. |
front 62 What are key costimulatory interactions? | back 62 CD80/86–CD28 and CD40–CD40L. |
front 63 Why is CD40–CD40L important? | back 63 It provides the main activation signal to B cells. |
front 64 What is somatic hypermutation? | back 64 Introduction of mutations in antibody genes. |
front 65 What is affinity maturation? | back 65 Selection of B cells with higher affinity antibodies. |
front 66 What is AID? | back 66 Enzyme that converts C to U in DNA to induce mutations. |
front 67 What are mutational hotspots? | back 67 Regions of DNA more prone to mutation. |
front 68 How does AID increase antibody affinity? | back 68 Creates variants, then highest-affinity B cells are selected. |
front 69 What are antibody kinetics? | back 69 Timing of antibody production (early IgM, later IgG/IgA/IgE). |
front 70 What is class switching? | back 70 Changing antibody isotype without changing antigen specificity. |
front 71 What controls class switching? | back 71 Cytokines from Tfh cells. |
front 72 What does AID do in class switching? | back 72 Creates DNA breaks for recombination. |
front 73 How is antibody isotype determined? | back 73 By cytokines from Tfh cells. |
front 74 Where do activated B cells go? | back 74 Infection sites and bone marrow. |
front 75 What is the function of B cells in tissues? | back 75 Secrete antibodies to neutralize pathogens. |
front 76 What are differences between naïve and memory B cells? | back 76 Naïve are slow and low affinity; memory are fast, high affinity, and often class-switched. |
front 77 What are general characteristics of TI responses? | back 77 Fast, no T cell help, mostly IgM, weak memory. |
front 78 What types of antigens trigger TI responses? | back 78 Polysaccharides, lipids, and repetitive structures |