Nature and Action of a New Clotting Factor Obtained From Erythrocytes

Abstract

Erythrocytes were found to contain a clotting factor differing from any known agent. It has almost no thromboplastic activity as measured by the one-stage prothrombin time but when added to normal platelet-poor plasma, it brings about a much greater consumption of prothrombin than an extract of platelets. When the hemolysate is added to plasma from a severe hemophiliac, no demonstrable consumption of prothrombin occurs which indicates that the erythrocyte factor requires thromboplastinogen as a co-factor. If increasing amounts of thromboplastinogen are added to hemo-philic plasma containing an excess amount of hemolysate factor, the consumption of prothrombin is a straight-line function of the concentration of thromboplastinogen. By adding hemolysate to hemophilic blood, the prothrombin consumption becomes a quantitative measure of thromboplastinogen. In serum only a trace of the latter factor is found by this method. The erythrocyte factor is sensitive to pH changes and is most stable at pH 7.4. It is heat labile, is destroyed by acetone dehydration, by trypsin digestion but not by chymotrypsin B. Unlike platelet extract, its activity is unaltered by high centrifugation.