PLTs express FasL. (A) Expression levels of death ligands FasL and TRAIL in resting or ADP-activated murine PLTs and MEFs analyzed by western blot. Loading equivalency was assessed by Tom20 staining. (B) Human whole blood was stimulated with ADP (activated) or buffer (resting), fixed with PFA, and analyzed by flow cytometry. PLTs were gated by forward and side light scatter characteristics and analyzed for FasL expression using a PE-coupled FasL Ab. Data are mean ± SEM and are shown as percentage of control and IgG control represents the 100% control (n = 5). *P < .05 vs control. (C) Murine PLTs were stimulated with ADP and analyzed for surface expression of FasL by flow cytometry. Data are mean ± SEM and are shown as percentage of control. Resting PLTs represent the 100% control (n = 7). *P < .05 vs control. (D) PLTs were co-stained for the α-granular marker CD62P (green) and FasL (red). Staining was analyzed by confocal fluorescence microscopy. Scale bar, 5 µM.