Term
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Definition
In fetuses: liver and spleen
In adults: bone marrow |
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Term
| What is the half-life of B cells? |
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Definition
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Term
| What is the first differentiation of hematopoietic stem cells? |
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Definition
| Between the myeloid line and the lymphoid line |
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Term
| What cells have the potential to become T cells but default to the B cell line? |
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Definition
| Common lymphoid progenitor cells (CLP) |
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Term
| What markers do pro-B cells display on their surface? |
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Definition
| CD19 and CD45R, but no immunoglobulin |
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Term
| What drives pro-B cell proliferation? |
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Definition
| Stromal cells release IL-7 and stem cell factor, which binds to c-kit |
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Term
| What differences are there between early pre-B cell and late pre-B cell? |
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Definition
| The early pre-B has a heavy mu chain with only one allele expressed (allelic exclusion). In late pre-B cells, there is Vk/Jk and Vlambda/Jlambda recombination |
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Term
| What chains appear on immature B cells? |
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Definition
| Light chains forming mu-k or mu-lambda IgM molecules |
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Term
| How does an early pre-B cell get stimulated to proliferate? |
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Definition
| A pre-BCR with a surrogate light chain must react with a ligand, in addition to stimulation from IL-7 via stromal cells |
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Term
| What is a surrogate light chain? |
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Definition
| A structure similar to a light chain consisting of lambda5 and VpreB. It has tails that allow SLs to aggregate on the pre-B cell surface to enhance signaling |
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Term
| What effects does the pre-BCR have inside the cell? |
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Definition
| Expression of Rag1, Rag2, lambda5 and VpreB cease |
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Term
| How are immature B cells selected? |
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Definition
| Immature B cells that see self antigens undergo clonal deletion via apoptosis |
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Term
| What is receptor editing? |
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Definition
| A way to salvage self-reactive B cells by changing their light chains' antigen specificity. They re-express Rag and form new light chains until becoming functional |
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Term
| What is a consequence of B cell self-reactivity? |
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Definition
| It cannot receive help from T cells and will not receive survival signals such as Bcl-x |
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Term
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Definition
| B cells made by adults that do not self renew. They are foreign antigen specific and are a good source of memory cells |
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Term
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Definition
| Self-renewing, self-reactive B cells of fetal/neonatal origin that express CD5. They clear cellular debris by forming immune complexes, provide natural serum antibodies to many pathogens, do not undergo somatic hypermutation, and are poor memory cells |
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Term
| What is a consequence of B-1 cell self-renewal? |
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Definition
| It makes them a common source of B-cell line leukemias |
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Term
| Where are marginal zone B-cells found and what do they express? |
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Definition
| They are found in the marginal sinuses of the white pulp of the spleen and express CD21/35 and have C3 fragment complement receptors |
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Term
| What do the BCRs of marginal zone B cells do? |
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Definition
| They are mainly for common bacteria and are adapted for quick, potent antibody production to blood-borne antigens (sepsis) |
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Term
| What do each type of B cell secrete? |
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Definition
| Minor populations secrete mostly IgM, but B-2 cells secrete more IgG |
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