Serum Accelerator Factors and Antihemophilic Factor (AHF) in Early Phases of Clotting. ∗

Abstract

Summary

1. An eluate from BaSO₄-ad-sorption of normal serum is shown to have a marked effect on the clotting time in hemophilia without altering the defect in prothrombin utilization. 2. The eluate is shown to operate chiefly by reducing the latent period of prothrombin utilization. 3. The effect of this eluate on AHF assays is discussed. 4. The necessity of platelets for prothrombin conversion is demonstrated again under different experimental conditions. 5. AHF is shown to be required for the demonstration of maximal prothrombic activity in the prothrombin time test.