Caspase-1 is activated by Fas ligation and is required for Fas-ligation-induced IL-1β secretion and phenotypic maturation of DCs. (A) Western blot analysis of caspase-1 activation in DCs cultured in medium alone (C) or after stimulation with anti-Fas antibody Jo-2 (J), isotype antibody (I), or LPS (L) for the indicated times. (B) Inhibition of Fas-ligation-induced IL-1β secretion (i) and maturation marker CD86 expression in DCs (ii) by the relatively specific caspase-1 inhibitor Ac-YVAD. Comparable results were obtained from 3 independently conducted experiments.