Platelet surface-activated GPIIb-IIIa and P-selectin normalized to platelet surface CD41 fluorescence in controls and WAS/XLT patients. The following markers were measured with and without agonist stimulation: (A) FSC of platelets, (B) ratio of mean fluorescence for activated GPIIb-IIIa (PAC1) and CD41 mean fluorescence, and (C) ratio of mean fluorescence for P-selectin and CD41 mean fluorescence. Low ADP, 0.5 μM; high ADP, 20 μM; low TRAP, 1.5 μM; and high TRAP, 20 μM. Results are expressed as mean ± SEM with n = 8 for controls and n = 9 for WAS/XLT patients, and analyzed with 2-way ANOVA with Bonferroni posttest. *Significant difference (P < .05).