Antihemophilic Factor (AHF) Levels Following Transfusions of Blood,Plasma and Plasma Fractions. ∗

Summary

1. Canine and human hemophilic subjects were transfused with homologous blood or plasma, Dogs were also transfused with AHF-rich plasma fractions. The increase in plasma AHF levels following transfusions was proportional to the amount of AHF administered. Over half of the AHF activity disappeared within a few hours, although traces of AHF may persist for nearly a week. Frequent replacement transfusions are required if AHF levels as high as 5-10% are to be maintained. 2. Injection of potent plasma fractions into normal dogs resulted in transient supernormal AHF levels. Half of the injected AHF was lost in about 2 hours. 3. The minimum amount of AHF required to give normal values is not uniform with different clotting tests. AHF levels above 1% resulted in normal values for the clotting time and prothrombin utilization tests. Levels above 15% resulted in normal values for the PTT test.