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23 Cards in this Set
- Front
- Back
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where does B cell activation occur?
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in secondary lymphatic tissue
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What do mature B cells express?
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IgM and IgD
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what happens to naive B cells in the absence of antigen?
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they will die by apotosis
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what does antigen-driven activation of B cells lead to?
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this leads to the generation of plasma cells and memory B cells
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What are T cell independent activators of B cells?
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nonprotein antigens (LPS, lipids, nucleic acids)
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How do T cell independent activators work? what does it result in?
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these activated B cells by cross linking BCR and CR2.
this doesnt require t cell binding. This results in limited class switching, limited memory cell generation |
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What is used to T cell dependent activation of B cells?
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Proteins in class 2 MHC on B cell binds to TCR-
B-cell's CD40 then binds T cell. this results in extensive class switching, memory cell generation, and affinity maturation |
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What does the antigen mediated cross linking of the BCR result in?
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mitosis, expression of new surface molecules, and migration of cells
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Where B cells migrate to after activation?
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they migrate to the edge of the follicle (B zone)
they then interact with activated T helper cells. (2nd signal) |
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What receptors bind up during the second signal via Th cell interaction?
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CD40 on the B cell binds CD40L on activated T cell.
B7 on B cell binds D28 on T cell |
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what does the second signal from T-cells encourge a B cell to do?
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b cell proliferation and clonal expansion
(this takes place after CD40 (B cell) binds CD40L (activated T cell) and B7 (b cell) binds CD28 (T cell) |
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What do short lived plasma cells produce?
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IgM mostly
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What do long lived plasma cells produce?
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IgG and IgA (secrete low levels)
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What is heavy chain class switching? when does it happen?
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this is the switching of the base chain that a B cell produce (igM to IgG or something)
this happens after B cell activation and differentiation (CD40 and CD40L binding) |
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What is affinity maturation?
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this is somatic hypermutation, exons encoding the variabile regions of H/L chains undergo high levels of point mutations. used to strengthen binding
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what do follicular dendritic cells do?
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these are used to help select B cells with specific antigens for the bound antigen.
B cells do their hypermutation thing, then attempt to Bind follicular dendritic cells. IF they bind tight, then they live! |
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What markers do memory B cells express?
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mIgG, mIgA, mIgE
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What antibodys to memory B cells mostly produce?
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IgG
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What is antibody feed back?
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secreted IgGs inhibit continued B cell activation by forming Ag-Ab complexs- these bind Fcgamma receptors and BCR receptors
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what do anti-idiotype antibodies do?
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these are antibodies against the variable region of of BCR's and secreted anti bodies
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What do pts with B cell immunodeficiencies typically present like?
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reccurent pyrogenic infections (pus forming, from neutrophils) beginning at 6-12 months of age.
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What is XLA? (Brutons aggamalobulinemia)
How is it treated? |
these are low B cells, reccurent infections of encapsulated bacteria, (pneumoniae, influenzae, staph)
poorly differentated tonsils, adenoids, lymph nodes, and peyers patches. This is treated by IV IG- (gamma globulin) |
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What is hyper IgM syndrome?
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this is characterized by way high IgM levels, and next to no IgG, IgA, or IgE.
there is No CD40/CD40L interaction, to tell B cells to switch classes from their base IgM class (what they were created with) |
