Thursday, November 11, 2010

63 在胸腺(thymus)中,T細胞進行負選擇(negative selection)之目的是除去下列那種細胞?
T細胞受器(T cell receptor, TCR)基因重組失敗之T細胞
不能辨識自己MHC分子之T細胞
能辨識自己MHC呈獻自己peptide(self MHC + self peptide)之T細胞
能辨識外來MHC呈獻自己peptide(foreign MHC + self peptide)之T細胞



In mammals the process occurs in the thymus (T cells)[5][6] and bone marrow (B cells). These are the two primary lymphoid organs where T cells and B cellsmature. During the maturation phases of both T cells and B cells the cells are sensitive to antigen-recognition. Unlike mature peripheral lymphocytes, which become activated upon encountering their specific antigen, the immature lymphocytes respond to stimulation with antigen by undergoing a rewiring of the cellular processes. The response to antigen at this stage depends on the properties of the antigen, the cell type and the developmental stage, and can lead to the cell becoming non-responsive (anergic), undergoing directed suicide (negative selection), altering its antigen receptor (receptor editing) or entering a regulatory lineage

Central tolerance is the mechanism by which newly developing T cells and B cells are rendered non-reactive to self[

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