Ch. 11. B Cell Generation, Activation, and

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Ch. 11. B Cell Generation, Activation, and
Differentiation B cells develop in the bone
marrow B cells undergo Ag-induced activation and
differentiation in the periphery Activated B
cells give rise to Ab-secreting plasma cells
and memory cells
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p. 273
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p. 272
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Stages of B cell maturation are distinguished by
cell-surface markers
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p. 274
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p. 276
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Why do only approx. 10 of B cells leave
the bone marrow? Negative selection of cells
that express Abs against self-antigens Cross-
linking of mIgM by self Ag may lead to cell
death or anergy Two kinds of Ags T-independent
(a few) dont need T cell help T-dependent (a
lot) need T cell help
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p. 279
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p. 279
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B cell activation stimulates much
signal transduction Process has many parallels
to T cell activation
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p. 280
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p. 282
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p. 283
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Initial exposure to antigen mIg has low
affinity Co-receptor may help with signaling
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p. 285
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p. 286
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p. 289
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p. 290
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Where is the humoral response actually
induced? Lymphoid tissues concentrate
antigens Spleen from blood Lymph nodes - from
tissues Lots of APCs in lymph nodes dendritic
cells, macrophages
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p. 292
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p. 294
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p. 296
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Generation of plasma cells Little membrane Ig
RNA processing supports secreted Ig Heavy and
light chain genes are transcribed at a higher
rate than in other cells Memory cells are
selected from a similar population of
high-affinity cells
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p. 297
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Immune system may be nonresponsive (tolerant)
of antigen Antigen-mediated dosage competing
antigen previous exposure to one antigen may
suppress response to another Antibody-mediated p
reformed antibody can interfere
with immunization (by competing for
antigen?) Maternal Ab may interfere with
immunization
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p. 298
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Summary of B cell maturation Antigen-independent
in bone marrow, antigen- dependent in
periphery TH cells are required for B cell
activation Affinity maturation, class switching
and formation of plasma and memory cells occur
in germinal centers Protective mechanisms such
as clonal anergy may prevent the formation of
self-reactive cells