Platelet surface expression of activation markers in controls and WAS/XLT patients. The following markers were measured with and without agonist stimulation: (A) percentage of platelets positive for activated GPIIb-IIIa (measured by PAC1 binding), (B) mean fluorescence for activated GPIIb-IIIa (PAC1), (C) percentage of platelets positive for P-selectin, (D) mean fluorescence for P-selectin, (E), mean fluorescence for CD41, and (F) percentage of cells positive for PS (measured by annexin V binding). Low ADP, 0.5 μM; high ADP, 20 μM; low TRAP, 1.5 μM; high TRAP, 20 μM; low convulxin, 1 ng/mL; and high convulxin, 5 ng/mL. Results are expressed as mean ± SEM with n = 8 (n = 7 for panel F) for controls and n = 9 (n = 6 for panel F) for WAS/XLT patients, and analyzed with 2-way ANOVA with Bonferroni posttest. *Significant difference (P < .05).