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  • Title: Monochloramine enhances Fas (APO-1/CD95)-induced apoptosis in Jurkat T cells.
    Author: Ogino T, Ma Y, Than TA, Omori M, Okada S.
    Journal: J Leukoc Biol; 2000 Jan; 67(1):46-52. PubMed ID: 10647997.
    Abstract:
    Monochloramine derivatives are physiological oxidants produced by activated neutrophils. We report the effects of chemically prepared monochloramine (NH2Cl) on Fas-induced apoptosis in Jurkat T cells. When the cells were pretreated with NH2Cl (20-70 microM), subsequent addition of apoptosis-inducing anti-Fas antibody resulted in a synergistic enhancement of apoptosis. Treatment of NH2Cl (50-70 microM) alone resulted in a slight but definite apoptosis. Caspase activities, as measured by DEVD and IETD cleavage activities, were also elevated synergistically by NH2Cl + anti-Fas antibody stimulation. Moreover, a broad caspase inhibitor, Z-VAD-fmk, almost completely inhibited the apoptosis induced by NH2Cl and/or anti-Fas antibody. Fas expression on the Jurkat cell surface was not affected by the NH2Cl treatment. After 3 h of NH2Cl treatment, when the apoptosis was beginning to increase, the cells showed cytochrome c release from mitochondria, proteolytic activation of caspase 9, and poly (ADP-ribose) polymerase cleavage, regardless of Fas stimulation. Z-VAD-fmk almost completely inhibited this poly (ADP-ribose) polymerase cleavage, but not cytochrome c release. By contrast, Fas stimulation alone resulted in neither cytochrome c release nor caspase 9 activation at 3 h, and the increase in the DEVD cleavage activity and apoptosis became evident at later time points. These results suggested that NH2Cl enhanced Fas-induced apoptosis through the cytochrome c release and caspase 9 activation at the early stage of apoptosis. Chloramines derived from acute inflammation may modify immune reactions, such as cell-mediated cytotoxicity and some autoimmune diseases, by the enhancement of Fas-induced apoptosis.
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