Antiserum against factor IX shortens the bovine thromboplastin coagulation time of human plasma.

Abstract

Abstract The one-stage prothrombin time was determined with bovine thromboplastin after the addition of a high-titred sheep antiserum against human factor IX. In normal plasma and plasma from patients with hemophilia B and a normal amount of plasma factor IX antigen, the addition of antiserum resulted in a shortening of the prothrombin time. Serum from a sheep which had not been immunized had no such effect. The antiserum had no effect on the prothrombin time of plasma from patients with hemophilia B and no detectable plasma factor IX antigen (hemophilia B-). Incubation with antiserum also resulted in a shortening of the clotting time of normal plasma in the Thrombotest and had no effect on the clotting time of hemophilia B-plasma. Addition of purified factor IX to normal plasma increased the prothrombin time determined with bovine thromboplastin. The antiserum had no effect on the prothrombin time determined with human or rabbit thromboplastin. It is concluded that normal factor IX antigen and factor IX antigen from patients with hemophilia B+ probably act as inhibitors in the reaction between bovine thromboplastin, factor VII and factor X.