[Thrombomodulin as a clinical marker in thrombotic thrombocytopenic purpura. Japan TTP Study Group].

Endothelial cell injury may be common and a fundamental mechanism in thrombotic thrombocytopenic purpura (TTP). Thrombomodulin (TM) is an endothelium-associated cofactor for thrombin-induced protein C activation. TM also abrogates virtually all of thrombin's procoagulant activities. Soluble TM exists in circulating plasma as heterogeneous fragments and is regarded as a molecular marker, reflecting injury of endothelial cells. The plasma TM level is elevated in patients with TTP as compared with healthy subjects. It may reflect damage to vascular endothelial cells or organ failure in patients with TTP. Although, at present, there are no alternative means superior to TM for specifically evaluating the endothelial damage, further studies are needed before soluble TM can be recommended as a standard molecular marker for TTP.