Antithrombin III, plasminogen, plasmin, and alpha-2-antiplasmin in donor blood and plasma components

The functional levels of antithrombin III, plasminogen, plasmin, and alpha-2-antiplasmin were evaluated in sequentially derived fresh frozen plasma, cryoprecipitate, and cryo-poor plasma aliquots from 20 registered blood donors. Antithrombin III is the major plasma inhibitor of the serine proteases of the procoagulant system. Plasminogen, the proenzymatic form of plasmin, is the primary endogenous profibrinolytic moiety; alpha-2-antiplasmin is the principal intermediate acting inhibitor of plasmin. As congenital or acquired deficiencies of antithrombin III and/or plasminogen predispose to thrombosis, and as these agents may be consumed in acute thrombosis, the goal of this investigation was to discern those plasma components which potentially might maximize both antithrombotic and fibrinolytic activities if used therapeutically. Using enzyme specific synthetic substrate methods, it was determined that no spontaneous plasmin activity was evident through phlebotomy or component processing and storage. Analysis of variance showed antithrombin III to be significantly decreased in cryoprecipitate as compared to the other components (p less than 0.0001). Furthermore, the level of antithrombin III or plasminogen in cryo-poor plasma and fresh frozen plasma was not statistically different. Also, the alpha-2-antiplasmin level was not statistically different among the specimen groups. Since fresh frozen plasma and cryo-poor plasma contain comparable total quantities of antithrombin III and plasminogen and as most of the activity of factors I, V, VIII, and XIII is diverted into cryoprecipitate, it is suggested that cryo-poor plasma may be preferable to fresh frozen plasma for the treatment of thrombosis associated with or complicated by antithrombin III and/or plasminogen deficiency.