Normal prostacyclinlike activity and response to plasma exchange in thrombotic thrombocytopenic purpura: report of 2 cases.

2 cases of acute idiopathic thrombotic thrombocytopenic purpura are reported. Both of them were treated with plasma exchange, antiplatelet drugs and prednisolone and both completely recovered. Plasma exchange appeared to be the critical treatment. In 1 of these cases the prostacyclinlike activity released from venous tissues and the ability of plasma to stimulate synthesis of prostacyclinlike activity from venous tissues exhausted after repeated washings were investigated. Both activities were detectable and comparable to those of a healthy control. These findings do not support the hypothesis of a major role played by the prostacyclin system in the pathogenesis of thrombotic thrombocytopenic purpura.