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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negative selection
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positive selection
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positive
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None of the above
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Detailed explanation-1: -In positive selection, T cells in the thymus that bind moderately to MHC complexes receive survival signals (middle). However, T cells whose TCRs bind too strongly to MHC complexes, and will likely be self-reactive, are killed in the process of negative selection (bottom).
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 of T Cells Double positive ab TCRlow cells must successfully undergo positive and negative selection before they can leave the thymus. 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-4: -Precursors of T cells migrate from the bone marrow and mature in the thymus. This process is similar to that for B cells, including the sequential rearrangement of antigen receptor gene segments.