Role of FcRand factor XIIIAin coated platelet formation

coated platelets. Following dual stimulation with the collagen receptor agonist convulxin and thrombin, 68% of platelets from C57BL/6 mice acquired the coated platelet phenotype, defined by high surface levels of fibrinogen and von Willebrand factor and decreased binding of the IIb3 activation-dependent antibody PE-JON/A. In FcR / mice, only 10% of platelets became “coated” after dual stimulation with convulxin plus thrombin (P < .05 vs C57BL/6 platelets). Decreased coated platelet formation in FcR / platelets was accompanied by decreased annexin V binding (P < .01) and decreased platelet procoagulant activity (P < .05). Platelets from FXIIIA / mice did not differ from control platelets in coated platelet formation or annexin V binding. We conclude that FcR, but not factor XIIIA, is essential for formation of highly procoagulant coated platelets following dual stimulation with collagen and thrombin. (Blood. 2005;106:4146-4151)