Objective: To explore the change in the protein content and procoagulant activity of platelet-associated tissue factor (TF) in thrombotic diseases.
Methods: Platelets were isolated with Sepharose 2B gel column. ELISA was employed to detect the TF protein content in the lysates of washed platelets, procoagulant activity of platelet-associated TF was measured with one stage clotting time assay.
Results: A certain amount of TF antigen (16.37 +/- 6.39) ng/L was detected in resting platelets in normal controls. The procoagulant activity of resting platelets and platelets activated by collagen were (0.89 +/- 0.26), (2.27 +/- 0.24) U/ml respectively. While specific TF McAb was added, the procoagulant activity of activated platelets can be markedly inhibited (1.39 +/- 0.28) U/ml (P < 0.001). It is thus proved that the procoagulant activity of activated platelets mainly comes from TF. TF protein content of the lysates of washed platelets in coronary heart disease group, brain infarction group and diabetes mellitus group was (20.71 +/- 8.78), (23.83 +/- 8.03), (22.12 +/- 8.24) ng/L respectively. The procoagulant activity of platelets without collagen treatment in these thrombotic diseases was (1.71 +/- 0.24), (1.69 +/- 0.25), (1.75 +/- 0.31) U/ml respectively. When specific TF McAb was added specific TF McAb, the procoagulant activity was (1.43 +/- 0.25), (1.39 +/- 0.25), (1.40 +/- 0.29) U/ml respectively. The TF protein content of lysates of washed platelets and the procoagulant activity of platelets without collagen treatment in patients with thrombotic diseases were significantly higher than those in normal controls. This procoagulant activity can be inhibited by TF McAb (P < 0.01).
Conclusion: The change in platelet-associated TF in thrombotic diseases may contribute to the maintenance of hypercoagulability.