Action of Erythrocyte Extract on the Prothrombin Consumption Test

¹ From the Department of Biochemistry, Marquette University School of Medicine, Milwaukee, Wisconsin

The prothrombin consumption time for human and rabbit whole blood and for platelet-rich plasma is approximately the same. The addition of an extract of human erythrocytes to the blood or plasma before clotting increases prothrombin consumption significantly except in platelet-poor rabbit plasma. If a mixture of aged normal serum and an extract of erythrocytes is added to the latter, the consumption of prothrombin is greatly increased. This potentiating activity of normal aged serum is also present in aged hemophilic serum, but is diminished in the serum from a patient with hemophilia B (PTC deficiency). The serum factor is destroyed at 60°C and is adsorbed with Ca₃(PO₄)₂. The findings suggest that the cofactor of erythrocytin, the clotting factor in the erythrocyte, may be related to the agent lacking in hemophilia B.