Objectives: To elucidate partly the mechanism of homocysteine-associated thrombosis.
Methods: 1. Thrombomodulin (TM) antigen distribution on human vascular endothelial cell (EC) membrane was assayed by immune-fluorescence histochemistry stain and flow cytometry; 2. Plasma heparin cofactor activity was measured by chromogenic method.
Results: Homocysteine (Hcy) significantly down-regulated the expression of TM on EC, with a concentration-dependent manner; 2. Hcy did not influence platelet aggregation induced by ADP and thrombin; 3. Hcy exerted no effects on the activities of antithrombin III or heparin cofactor.
Conclusion: The effect of Hcy in developing thrombosis may be associated with an inhibitory action on EC TM expression; which was independent of platelet aggregation or heparin cofactor activity.