Some Factors that Influence Utilization of Antihemophilic Activity During Clotting. ∗

Summary

A study has been made of the effects of various plasmas, sera and fractions on AHF in stabilized (BaSO₄-adsorbed) plasma. Only reagents that provided a source of thrombin caused AHF to disappear after recalcification. Materials tested that produced loss of AHF were: normal, hemophilic, PTC-deficient and Stuart factor deficient plasmas and hemophilic serum. All contained prothrombin. Those that produced no significant loss were: dicumarol plasma, normal serum, SAF, PTC and adsorbed serum; they contained no detectable prothrombin. Slow prothrombin conversion (e.g. Stuart plasma, platelet-poor plasma) was accompanied by slow AHF utilization. Removal of fibrinogen from reaction mixtures did not abolish AHF loss. Purified prothrombin caused utilization of AHF in proportion to its concentration if cephalin and calcium ions were present to cause conversion to thrombin. Preformed thrombin was also effective in proportion to its concentration; its effect was accelerated by calcium ions. The significance of these findings is discussed in relation to blood preservation, intravascular coagulation and basic clotting reactions.