Immunofluorescence study on thrombolysis with special reference to the patterns of distribution and the contents of fibrin, plasminogen, alpha2-macroglobulin and urokinase in artificial thrombi.

By the immunofluorescence technique, fibrin, plasminogen and alpha2-macroglobulin demonstrated a similar basic pattern of distribution in the artificial thrombi, rimming the platelet aggregates in the white part and forming a network structure in the red part. The content of plasminogen seemed to be higher in the red part than in the white part. After superfusion with urokinase solution, urokinase was found in a similar pattern of distribution of that of fibrin. The content of urokinase seemed to be higher in the red part, especially in its outer area, than in the white part. It is concluded that urokinase diffused into the artificial thrombi can convert plasminogen, trapped onto fibrin in threads to plasmin. Poor lysibility of the white part might be due to thick strands of fibrin, a low content of plasminogen and a low diffusibility of plasminogen activator, in addition to the antifibrinolytic activity of platelets.