ACTIVATED PLATELETS IN PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA

One of the major causes of morbidity and mortality in paroxysmal noctu rnal haemoglobinuria (PNH) is venous thrombosis. We have studied fibri nolysis, coagulation and platelets in 11 patients with PNH in an attem pt to identify the possible mechanism(s) of thrombosis in PNH. In this study we did not identify any fibrinolytic defects, evidence of coagu lation activation, nor reduction in coagulation inhibitors. In contras t, in this cohort of 11 PNH patients we have identified varying degree s of platelet activation as defined by the surface expression of activ ation-dependent proteins and the binding of adhesive proteins to the p latelet surface. The thrombotic events in PNH usually occur in the ven ous system. Our studies and previous experimental studies suggest that anti-platelet therapy may be efficacious in reducing the incidence an d severity of venous thrombosis in PNH.