Fas antigen (CD95) in pure erythroid cell line AS-E2 is induced by interferon-gamma and tumor necrosis factor-alpha and potentiates apoptotic death

We investigated the expression of Fas antigen (CD95) in the pure erythroid cell line AS-E2 in the presence and absence of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), TNF-alpha induced apoptosis i n AS-E2 cells, whereas IFN-gamma did not. In culture containing no IFN-gamm a, or TNF-alpha, AS-E2 cells expressed Little Fas antigen. However, IFN-gam ma and TNF-alpha both induced expression of Fas antigen and its mRNA within 24 hours after the stimulation. When anti-Fas monoclonal antibody (IgM) wa s added to AS-E2 cells after the induction of Pas expression, AS-E2 cells u nderwent apoptosis as shown by the induction of DNA fragmentation, This apo ptotic change was inhibited by an inhibitor of caspase-3-like proteases (Ac -DEVD-CHO) and an inhibitor of CED3/ICE family proteases (Z-Asp-CH2-DCB) bu t not by an inhibitor of caspase-1-like proteases (Ac-YVAD-CHO), suggesting a role for caspase-3-like proteases in Pas-receptor signaling. Although AS -E2 cells expressed Fas ligand mRNA, treatment with ZB4, an antibody that i nhibits Fas-mediated cell death, failed to suppress IFN-gamma- or TNF-alpha -mediated cytotoxicity. These findings suggest that the late erythroid prog enitor cells are negatively regulated by IFN-gamma and TNF-alpha, both of w hich are capable of inducing functional Fas expression, (C) 1999 Internatio nal Society for Experimental Hematology, Published by Elsevier Science Inc.