Disulfide-exchange–induced thiol expression is necessary for αIIbβ3 ligation but not for agonist-induced expression of P-selectin.
Platelets were stimulated with collagen (A), CRP-XL (B), or thrombin (C) in the presence of FITC-fibrinogen (squares), monoclonal antibody PAC-1 (diamonds), or anti–P-selectin (triangles) and of increasing concentrations of pCMPS, bacitracin, or RL90 (solid lines) or a matched IgG control (broken lines). The total fluorescence at each concentration of inhibitor was expressed as the percentage of fluorescence in the absence of inhibitor, defined as 100%. Data are mean ± SD from 4 different determinations using samples from 4 different donors. Concomitant determination of bound FITC-fibrinogen, PAC-1 and, anti–P-selectin to agonist-stimulated platelets distinguished between inhibition of αIIbβ3activation and platelet stimulation.
