Hemophilia: Quantitative Studies of the Coagulation Defect

Abstract

The prothrombin-consumption test described by one of us in 1947 1 was based on the assumption that the amount of prothrombin remaining in serum when blood clotted under standardized conditions was a measure of the thromboplastin that resulted from the interaction of platelets with a plasma constituent which was designated as thromboplastinogen. It was concluded that the poor consumption of prothrombin observed when hemophilic blood clotted was caused by a lack of this plasma factor and that, therefore, the method could be employed for its assay. This assumption was supported by the significant increase in prothrombin consumption obtained after giving a hemophiliac a transfusion of normal blood or plasma. In mild hemophilia, however, the results were not always consistent, and, peculiarly, it was observed that when the platelet-rich plasma of such patients was clotted the prothrombin consumption was lower and more constant than when the test was done on whole blood.2This observation led to the discovery that the erythrocytes contain a potent clotting factor which is distinct from all the known primary clotting agents of the blood.3 The name "erythrocytin" is proposed for this substance.When the erythrocyte factor is added to normal plasma depleted of platelets, an ex¬ ceedingly high consumption of prothrombin is obtained, which shows not only that the new agent can completely replace platelets but also that it is more potent than the latter. Strikingly, no measurable amount of pro¬ thrombin consumption occurs when an ex¬ tract of hemolyzed erythrocytes (hemolysate) or a partially purified preparation of erythro¬ cytin is added to the blood or plasma of a severe hemophiliac. When a purified prepa¬ ration of thromboplastinogen is added to hémophilie blood or plasma and the pro¬ thrombin consumption with a fixed excess of hemolysate is determined, a straight-line proportion between the concentration of thromboplastinogen and the prothrombinconsumption time is obtained.4 The possi¬ bility of utilizing this observation for the development of a method to assay blood for its concentration of thromboplastinogen was investigated, and the results of this study, especially as it pertains to hemophilia, are reported in this paper. METHODS AND MATERIALSBlood was collected with a silicone-coated syringe and needle and transferred to containers similarly coated which were immersed and kept in an ice bath.The clotting time was carried out by standardized procedure previously described.5 The normal range is 5 to 10 minutes.

Erythrocytes and Blood Coagulation

“…Consistent with these findings, Quick was able to develop a quantitative assay for Factor VIII using hemolyzed erythrocytes as a partial thromboplastin, much as cephalin is used in the partial thromboplastin in the PTT test (Quick and Hussey 1956). This basic assay was used later by Bentley and Krivit (1 960) in a study of 21 carrier and 5 probable female carriers of hemophilia.…”