In:
Clinical and Developmental Immunology, Hindawi Limited, Vol. 2012 ( 2012), p. 1-6
Abstract:
Survival of T cells in both the central and peripheral immune system determines its ultimate function in the regulation of immune responses. In the thymus, developing T cells undergo positive and negative selection to generate a T cell repertoire that responds to foreign, but not self, antigens. During T cell development, the T cell receptor α chain is rearranged. However, the first round of rearrangement may fail, which triggers another round of α chain rearrangement until either successful positive selection or cell death occurs. Thus, the lifespan of double positive (CD4 + CD8 + ; DP) thymocytes determines how many rounds of α chain rearrangement can be carried out and influences the likelihood of completing positive selection. The anti-apoptotic protein Bcl-x L is the ultimate effector regulating the survival of CD4 + CD8 + thymocytes subject to the selection process, and the deletion of Bcl-x L leads to premature apoptosis of thymocytes prior to the completion of the developmental process. In addition to its critical function in the thymus, Bcl-x L also regulates the survival of peripheral T cells. Upon engagement with antigens, T cells are activated and differentiated into effectors. Activated T cells upregulate Bcl-x L to enhance their own survival. Bcl-x L -mediated survival is required for the generation of effectors that carry out the actual immune responses. In the absence of Bcl-x L , mature T cells undergo apoptosis prior to the completion of the differentiation process to become effector cells. Therefore, Bcl-x L ensures the survival of both developing and peripheral T cells, which is essential for a functional immune system.
Type of Medium:
Online Resource
ISSN:
1740-2522
,
1740-2530
Language:
English
Publisher:
Hindawi Limited
Publication Date:
2012
detail.hit.zdb_id:
2817541-4
detail.hit.zdb_id:
2119272-8
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