Summary
Prothrombin is utilized in hemophilia B blood when a platelet cofactor I concentrate
is added. It is not well utilized when the same preparation is added to hemophilia
B plasma, hemophilia A plasma, or hemophilia A blood. Platelet factor 3 concentrates
did not promote prothrombin utilization. Mixtures of platelet cofactor I and platelet
factor 3 (threone) give prothrombin utilization under all conditions tested in hemophilia
A and B.