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12 Cards in this Set
- Front
- Back
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What are the 5 phases of T cell development
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1. Arrival in the thymus and initial proliferation
2. Positive selection 3. Negative selection 4. Entery to the peripheral T cell pool 5. Terminal antigen stimulated differentiation into effector and memory cells |
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What is thymic stroma composed of
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Cortical and medullary epithelial cells that play important roles in T cell development. Dendritic cells and macrophages also play important roles
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What is the earliest stage of T cell development called
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The double negative stage, because the cells do not express CD4 or CD8
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Recombination of which TCR loci occurs first
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Beta, Gamma and Delta
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How many successive rearrangements are possible at the Beta chain locus
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Two, because there are two cassettes of D and J segments
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Expression of the pre-T cell receptor signals for what
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Initiation of CD4 and CD8 co-receptor expression and the cells become double positive. Also signals for cessation of recombination at the Beta chain locus and for initiation of recombination at the alpha chain locus
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What is positive selection
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A process where those TCRs that can interact productively with self-MHC are selected
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Where does positive selection of T cells occur
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The thymic cortex, and is mediated by cortical epithelial cells
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In the development of T cells, what does productive MHC interaction signal
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Down regulation of either CD4 or CD8, and cessation of alpha chain rearrangment
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What is negative selection
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TCRs that interact too strongly with complexes of self MHC and peptide (autoreactive) are elimated from the pool of developing T cells
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Where does negative selection of T cells (central tolerance) take place
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Primarily at the cortico-medullary junction, and is mediated by dendritic cells and macrophages.
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What are some T cell neoplasias
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T cell acute lymphoblastic leukemia (T-ALL); Lymphoblastic lymphoma; Adult T cell leukemia/lymphoma (HTLV-1)
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