Cartoon representation of platelet activation markers associated with bleeding score independent of platelet count in ITP patients. (A) Patients with high bleeding scores, where low concentration TRAP yields a low percentage of PAC1- and P-selectin–positive platelets. (B) Patients with low bleeding scores, where low concentration TRAP yields a high percentage of PAC1- and P-selectin–positive platelets. (A-B) thus represent patients with different bleeding tendencies despite an equal number of circulating platelets.