FcRγ promotes T cell apoptosis in Fas-deficient mice.

Autor: Juvet SC; Division of Respirology, University Health Network, Toronto General Research Institute, University of Toronto, Toronto, ON, Canada M5G 1L7. Stephen.juvet@mail.utoronto.ca, Thomson CW, Kim EY, Joe B, Adeyi O, Zhang L
Jazyk: angličtina
Zdroj: Journal of autoimmunity [J Autoimmun] 2013 May; Vol. 42, pp. 80-93. Date of Electronic Publication: 2013 Jan 10.
DOI: 10.1016/j.jaut.2012.12.002
Abstrakt: Deficiency of Fas or its ligand leads to lymphocyte accumulation, lymphadenopathy, splenomegaly, and autoimmunity in mice and humans. Although the Fas pathway is important for limiting the number of peripheral T cells, inactivation of other pro-apoptotic molecules can also perturb T cell homeostasis independently of and/or in concert with Fas deficiency. Here, we show that combined deficiency of Fas and the Fc receptor common γ signaling chain (FcRγ) results in worsened T cell accumulation in comparison with mice lacking Fas alone, with a particularly marked increase in the number of TCRαβ(+)CD4(-)CD8(-) double negative (DN) T cells. LPR FcRγ(-/-) mice exhibited reduced survival due to progressive lymphadenopathy. We further investigated the mechanisms whereby FcRγ deficiency promotes lymphoproliferative disease in Fas-mutant mice. Interestingly, there were no significant differences in T cell proliferation between LPR FcRγ(+/+) and LPR FcRγ(-/-) mice in vivo and in vitro. However, FcRγ deletion resulted in significantly decreased peripheral T cell apoptosis. Importantly, the observed increase in apoptosis was restricted to a subset of FcRγ(+) T cells. These T cells, but not those lacking FcRγ expression, exhibited increased activation of caspases 3 and 9, indicating a role for FcRγ in driving their apoptosis. FcRγ(+) DN T cells also showed enhanced sensitivity to TCR restimulation-induced cell death (RICD) despite lacking Fas, suggesting that TCR stimulation of autoreactive T cells in vivo may serve to eliminate FcRγ(+) T cells and thus exert partial control over lymphoproliferative disease. Hence, our data reveal a novel role for FcRγ in promoting peripheral T cell apoptosis in Fas-deficient mice, which may be of significant value in understanding autoimmune lymphoproliferative syndromes.
(Copyright © 2012 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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