Platelet aggregation and αIIbβ3 activation induced by Cvx are altered in both patients. (A) Aggregation of washed platelets was initiated by increasing concentrations of Cvx (200-800 pM) for 3 minutes. Aggregation was expressed as the percentage change in light transmission, with the value of the blank (buffer without platelets) set at 100%. Tracings are representative of at least 2 experiments per patient. (B) Quantification of activated αIIbβ3 at the surface of washed platelets was assessed by flow cytometry by binding of the mAb PAC1 to control and P1 and P2 platelets upon activation with Cvx (200-800 pM). (C) The same experiment was conducted in the presence of apyrase (2 U/mL) and indomethacin (10 μM). Results are representative of 2 experiments for each patient. (D) Adherence and thrombus size were investigated on collagen matrix (50 μg/mL) in the presence or absence of apyrase (2 U/mL) and indomethacin (10 μM) at high shear rate (1500 s⁻¹) after 3 minutes. Platelet adhesion was expressed as covered surface (%) and thrombus size as total integrated fluorescence intensity (IFI) from 2 experiments carried out in triplicate. Data are presented as the mean ± SEM and statistical differences were determined using 1-way analysis of variance followed by the Tukey multiple comparison test (*P < .05, **P < .01, ***P < .001). a.u, arbitrary units.