Studies of the pathogenesis and management of thrombotic thrombocytopenic purpura.

We have studied the pathophysiological signs and methods of management of thrombotic thrombocytopenic purpura (TTP) in our TTP patients. We showed that anti-platelet GP II b- III a monoclonal antibodies bound to human vascular endothelial cells (HUVEC). The binding rate of 125I-anti-platelet GP II b- III a monoclonal antibodies to HUVEC treated with TTP patients sera was decreased, compared with the value observed for HUVEC treated with normal sera. These findings showed that GP II b- III a like substances are expressed on HUVEC and that TTP patients sera appear to contain anti-platelet GP II b- III a antibodies which may attack and injure the endothelial cells. PGI2 stabilizing activity of plasma is measured by PGI2 inhibitory activity attenuation on normal platelet aggregation induced by ADP. PGI2 stabilizing activity decreases in acute phase, increases in remission, suggesting that there may be a relationship between pathogenesis of TTP and decreases of PGI2 stabilizing activity. We also showed that PGI2 analogue (beraprost sodium) was useful for prevention of relapse of TTP. Plasmapheresis has emerged as the treatment of choice of TTP. We found the effectiveness of the high molecular weight fraction (HMW-F) of plasma in chronic TTP patients. HMW-F of plasma may contain the main factor necessary for improvement of TTP.