Term
| what 3 processes happen in B/T cell maturation? |
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Definition
| 1) proliferation of immature cells. 2) expression of antigen receptor genes. 3) selection of lymphocytes that express useful antigen receptors |
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Term
| where do B/T cells arise? |
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Definition
| from bone marrow stem cells. |
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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
| what is the signal for proliferation? |
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Definition
| IL-7 = interleukin 7. Made by stromal cells in bone marrow and thymus. |
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Term
| What happens when you have a IL-7 deficiency ? |
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Definition
| Severe Combined Immunodeficiency Syndrome (SCID) |
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Term
| what codes for the antigen receptors? |
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Definition
| gene segments. These recombine during lymphocyte formation and go on to produce diverse antigen receptors, which means diverse B/T cell repertoire. |
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Term
| what happens if a pre-lymphocyte fails to express any antigen receptors? |
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Definition
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Term
| is having ANY receptor good enough? What is positive selection? |
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Definition
| No, keep only those T cells that can recognize self MHC molecules. |
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Term
| what is negative selection? |
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Definition
| keep only T/B cells that dont have too strong affinity to self antigens |
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Term
| what are the components of the germline configuration in bone marrow stem cells for antigen receptors? |
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Definition
| Leader sequence (L), Variable region genes (V), Diversity gene segment (D), Joining gene segment (J), Constant Region Genes (C) |
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Term
| which two gene segments are recombined on the first somatic recombination in the production of antigen receptors? What about the second? |
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Definition
| D and J. Second is when V segments come in. Bottom line is that combination arises and makes UNIQUE receptor because there are many different combinations. |
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Term
| what happens in b lymphocyte development? |
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Definition
| 1) gene rearrangements to produce antigen receptors. 2) selective retention/deletion of B cells (keep the good, get rid of bad) |
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Term
| what happens in Pro-B cell to Pre-B cell conversion? |
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Definition
| a Pre-B cell receptor complex is formed from addition of a mu heavy chain that combine with surrogate light chains + IgAlpha and IgBeta signaling molecules. |
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Term
| what is allelic exclusion? |
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Definition
| B cells can express Ig from only one of the two inherited parental alleles. Resulting in each cell only expressing a receptor of a single specificity |
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Term
| can you have a b cell receptor expression for Tetanus toxin and influenzae virus on the same cell? |
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Definition
| no! goes against allelic exclusion. |
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Term
| Second signal in B cell development: |
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Definition
| combinations of mu + kappa chains or mu + lambda chains yielding membrane associated IgM receptor and making an Immature B cell. |
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Term
| if a B cell is IgM+IgD+ ... |
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Definition
| it is mature and can respond to antigen in peripheral lymphoid tissues. |
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Term
| what happens if the B cell binding to an antigen in the bone marrow occurs with high affinity? |
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Definition
| further maturation stops! |
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Term
| During immunoglobulin gene recombination in B cells. which cells are positively selected for and which are negatively selected against? |
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Definition
| positively for cells with intact receptors. Negatively against cells with strong reception for self antigen. |
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