Interaction of plasma clotting factors with vascular endothelial cells in hemostasis and thrombosis with special reference to endothelial cell tissue factor.

The interaction of plasma clotting factors with vascular endothelial cells was investigated. Human umbilical cord vein endothelial cells generated tissue factor activity after treatment with various stimulators including IL-1. Cycloheximide inhibited production of the tissue factor in the cells, but did not affect the expression of the tissue factor activity on the surface of endothelial cells. Endotoxin-treated vascular endothelial cells activated Factor X in the presence of Factor VII and calcium ion. Activation of Factor X by endothelial cells with Factor VII was enhanced by the presence of both Factors VIII and IX. Binding study revealed that endotoxin-treated endothelial cells bound Factor IX. These data suggest that perturbed vascular endothelium expresses tissue factor activity on the cell surface, binds factor IX and in the presence of Factor VII, activates not only factor X but also Factor IX.