Term
| Primary B-cell encounter with antigen or primary immune response occurs in what tissue? |
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Definition
| Secondary lymphoid tissue |
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Term
| Where are B cells found in secondary lymphoid tissues ? |
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Definition
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Term
| Where are T cells found in secondary lymphoid tissues ? |
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Definition
| In regions surround follicles |
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Term
| Initiating stimulus for B-cell activation is ? |
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Definition
| Antigen-induced crosslinking of the B-cell receptor complex, followed by its endocytosis in a cytosolic endosome |
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Term
| Activated native B cells undergo clonal expansion that is detectable within ______ hours of immunization. |
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Definition
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Term
| This site in primary follicles is associated with B cell clonal expansion, isotype switching, affinity maturation, differentiation to plasma cells, and differentiation to memory B cells |
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Definition
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Term
| Which antibody isotype is not secreted ? |
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Definition
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Term
| Isotype switching (switch recombination) is what ? |
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Definition
| Process by which cells expressing IgM and IgD are modified at genomic level such that they produce Abs of different isotypes (IgA, IgE, or IgG) |
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Term
| What part of Ab determines an antibody's isotype ? |
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Definition
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Term
| Is isotype switching irreversible ? |
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Definition
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Term
| Disruption of what cytokine gene inhibits isotype switching / switch recombination ? |
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Definition
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Term
| What is affinity maturation (somatic mutation)? |
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Definition
Process that leads to gradual accumulation, with time after immunization, of higher affinity Abs for the immunizing antigen
Is due to point mutations that occur in the Ab "VDJ" gene region of both light and heavy chains |
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Term
| Differentiation of activated B cells to memory cells occurs where ? |
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Definition
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Term
| Entry of memory B cells into lymph nodes occurs via afferent lymphatics rather than high endothelial venules (HEVs) because |
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Definition
| memory B cells have reduced expression of L-selectin |
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Term
| What is BLyS (B cell stimulator) or BAFF (B cell activating factor) ? |
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Definition
| Plays a critical role in B cell selection and survival. |
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Term
| Release of BLyS in monocytes/macrophages and dendritic cells is... |
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Definition
triggered by crosslinking of FcgammaR by IgG, an opsonin
This provides a link b/w innate immunity and adaptive immunity |
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Term
| BLyS binds to what 3 diff. receptors ? |
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Definition
BR3, BCMA, and TACI
Interaction with BR3 provides the greatest affinity |
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Term
| BCMA receptor binding to BLyS does what ? |
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Definition
| BCMA is needed for the optimal generation of long-lived plasma cells |
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Term
| BR3 leads to B-cell survival by ? |
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Definition
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Term
| Abnormal production of BLyS causes what ? |
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Definition
| Survival of autoreactive B cells, triggering autoimmune disorders |
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Term
| Serum levels of BR3 has been reported in pts. with what disorders ? |
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Definition
| Rheumatoid arthritis, SLE, or multiple sclerosis |
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Term
| Down regulation of B cell activation and decreased BLyS receptor levels is due to... |
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Definition
| Colligation of FcgammaR2B-IgG/antigen with membrane bound Ab/antigen |
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Term
| What is negative signalling in B-cells ? |
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Definition
Inhibition of B cells following antigen induced activation
Occurs when secreted IgG crosslinks the membrane bound Abs with the FcgammaR integral membrane receptor |
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Term
| What is the only ligand for BR3 ? |
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Definition
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Term
| What are the two ligands for TACI and BCMA ? |
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Definition
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Term
| Secondary immune responses occur where ? |
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Definition
| May be initiated outside of secondary lymphoid tissues |
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Term
| Does secondary immune response produce a better result than primary immune response ? |
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Definition
| Yes, b/c response and effect is faster and greater |
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Term
| What are T-indep. antigens ? |
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Definition
| Can induce naive B-cell activation in absence of cognate interaction with T cells. |
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Term
| B-cell acativation in response to T-indep. antigens leads to what ? |
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Definition
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Term
| Example of T-indep. antigen is what ? |
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Definition
Low conc. of LPS
Pneumococcal polysaccharide |
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Term
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Definition
| Small molecules less than 5kd, become immunogenic when coupled to large proteins. Small molecule is a hapten and larger molecule is a carrier |
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Term
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Definition
They enhance the immune response to an antigen
Is important in immunization
Exs) are alum precipitate and Freund's complete adjuvant |
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Term
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Definition
| Naturally occuring molecules that have capacity to bind to and trigger proliferation of many clones of lymphocytes |
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Term
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Definition
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Term
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Definition
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Term
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Definition
Often bacterial products, which act in an oligoclonal manner to activate subsets of T-cells
They bind to T-cell receptor regions called VBeta |
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Term
| Does somatic recombination occur in germinal centers ? |
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Definition
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