DECREASED PLASMA TISSUE FACTOR PATHWAY INHIBITOR LEVELS IN PATIENTS WITH THROMBOTIC THROMBOCYTOPENIC PURPURA

We measured plasma levels of tissue factor (TF) and tissue factor path way inhibitor (TFPI) in patients with thrombotic thrombocytopenic purp ura (TTP) and disseminated intravascular coagulation (DIC) to examine the relationship between TFPI and vascular endothelial cell injury. TF antigen was detected in the plasma of healthy volunteers, and the lev els were significantly increased in the patients with DIC, but decreas ed slightly in those with TTP. Plasma TFPI levels were significantly d ecreased in patients with TTP compared with those in healthy volunteer s. The concentration of plasma thrombomodulin (TM) antigen was signifi cantly higher in those with TTP than in normal volunteers. One month a fter treatment, TTP patients showed a significant decrease in plasma T M levels, and a significant increase in plasma TFPI levels, but plasma levels of TF antigen were not significantly increased. As plasma TFPI /TF ratio was significantly increased after treatment, the hypercoagul able state was therefore improved after treatment. There was no signif icant difference in plasma TF and TFPI levels between those who achiev ed complete remission (CR) and those who died. However, plasma TM leve ls were significantly higher in those who died than in those who achie ved CR. Plasma TFPI levels might reflect injury of vascular endothelia l cells as do plasma TM levels, and decreased plasma TFPI/TF ratio and vascular endothelial cell injuries might play causative roles in TTP.