Thrombin increases the adhesion of washed human platelets to collagen.

Thrombin stimulates the adhesion of washed human platelets to fibrillar collagen. This phenomenon occurs also when platelets, before thrombin stimulation, are resuspended in the presence of prostaglandin E1 to minimize the release reaction. Enzymatic activity of thrombin is not necessary for the enhancement of platelet adhesiveness, since phenylmethylsulphonylfluoride inhibited thrombin is effective in this respect. Detachment of thrombin from thrombin treated platelets by the use of hirudin restores normal platelet adhesiveness to collagen.