A monoclonal antibody (SZ-53) against thrombomodulin inhibits thrombin-mediated release of t-PA and PGI2 from endothelial cells.

Monoclonal antibodies against thrombomodulin have become a useful means to study the structure and function of thrombomodulin. In this study, we used a monoclonal antibody against human thrombomodulin, named SZ-53, to investigate the function of thrombomodulin on the surface of cultured human umbilical vein endothelial cells. Preincubation of endothelial cells with SZ-53 before addition of thrombin not only inhibited thrombomodulin mediated activation of protein C, but also inhibited thrombin mediated release of t-PA and PGI2 from endothelial cells. The inhibitory effects depended on the concentration of SZ-53 IgG. According to our experimental results, we suggest that thrombomodulin on the surface of endothelial cells could participate in the regulation of thrombin mediated release of t-PA and PGI2 from these cells.