Summary
We measured plasma levels of tissue factor (TF) and tissue factor pathway inhibitor
(TFPI) in patients with thrombotic thrombocytopenic purpura (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 levels were significantly increased in the patients with DIC, but decreased
slightly in those with TTP. Plasma TFPI levels were significantly decreased in patients
with TTP compared with those in healthy volunteers. The concentration of plasma thrombomodulin
(TM) antigen was significantly higher in those with TTP than in normal volunteers.
One month after treatment, TTP patients showed a significant decrease in plasma TM
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 hypercoagulable state was therefore improved after
treatment. There was no significant difference in plasma TF and TFPI levels between
those who achieved complete remission (CR) and those who died. However, plasma TM
levels were significantly higher in those who died than in those who achieved CR.
Plasma TFPI levels might reflect injury of vascular endothelial cells as do plasma
TM levels, and decreased plasma TFPI/TF ratio and vascular endothelial cell injuries
might play causative roles in TTP.