Plasmin inactivation in plasma.

Inhibition and inactivation of plasmin is ascribed to alpha2-macroglobulin, alpha1-antitrypsin and c1-esterase inhibitor. In an "overall" inactivation test of plasmin in plasma, which comes perhaps closest to rapid inactivation of plasmin in the circulating blood, we only found a correlation between the immunological concentration of alpha2-macroglobulin and the plasmin-inactivating capacity of the plasma, but no correlation with the immunological concentration of the other inhibitors mentioned. Therefore, alpha2-macroglobulin seems to be the most important plasmin inhibitor in relation to thrombosis.