OVERVIEW OF THE IMMUNE SYSTEM
LYMPHATIC AND IMMUNE SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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T-cells that bind MHC survive
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T-cells that bind MHC die
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T-cells that bind self antigens survive
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T-cells that bind self antigens die
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T-cells that do NOT bind MHC die
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Detailed explanation-1: -Cells which have successfully rearranged ab TCR will die in the thymus cortex if they do not bind self MHC within 3-4 days.
Detailed explanation-2: -Positive selection of T cells in the thymus is a fundamental step in the generation of a responding T cell repertoire: only those T cells survive that recognize human peptides presented on the surface of cortical thymic epithelial cells.
Detailed explanation-3: -Positive selection In this process, cells in the thymus present short pieces of proteins, called peptides, on their own MHC class I and class II molecules, allowing immature T cells to bind. If TCRs are incapable of binding, the T cell will undergo a type of cell death celled apoptosis.
Detailed explanation-4: -Positive selection involves targeting the desired cell population with an antibody specific to a cell surface marker (CD4, CD8, etc.). The targeted cells are then retained for downstream analysis. Negative selection is when several cell types are removed, leaving the cell type of interest untouched.
Detailed explanation-5: -Negative selection deletes T cells with high affinity for self-peptides via apoptosis, thus ensuring selftolerance, and is presumed to reflect strong signaling via TCR recognition of peptide–MHC complexes on APC.