Platelet function in sickle cell disease during steady state.

Platelet function was investigated in 37 patients with sickle cell disease during steady state. The measurement of platelet aggregation in whole blood, demonstrating interaction of sickle cells and platelets, showed increased activity in patients compared to controls. In contrast, by classical platelet aggregation in platelet-rich plasma (PRP) we observed decreased platelet aggregation in sickle cell patients. Aggregation of washed platelets appeared identical in patients and controls beta thromboglobulin (beta TG) and platelet factor 4 (PF4) as well as fibrinopeptide A (FPA) plasma levels were increased in patients with sickle cell disease. These results suggest that in sickle cell patients there is in vivo platelet stimulation, which may therefore appear "exhausted" in patients plasma during in vitro studies, and also a possible role of coagulation in the pathophysiology of sickle cell disease as supported by high levels of FPA.