Peculiar Disorder of Plasma Thromboplastin Production

Abstract

ONE of the several functions of platelets is participation in the formation of plasma thromboplastin. Recently, we encountered in the blood of a patient an agent with the unprecedented action of specifically hindering this activity. Thus, the presence of his plasma or serum in the incubation mixture inhibited the generation of plasma thromboplastin¹. Compared with a normal control (Table 1) the derangement, as estimated from the clotting time of the substrate, was more apparent on reducing the number of platelets (experiments B and C) and practically abolished on using a concentrated suspension (experiment D). Antihæmophilic globulin and Christmas factor levels² were determined in the presence of excess platelets; normal results were obtained. The patient's platelets were fully active in the thromboplastin generation test. Pre-incubation of normal platelets with patient's plasma or serum did not cause further deterioration in the production of plasma thromboplastin, indicating that the inhibitor has a retarding but not a destructive action on the platelet thromboplastin component. Further study has shown that this inhibitor counteracts the combination of platelets with antihæmophilic globulin and Christmas factor; the activity of other blood-clotting factors or their intermediate products were uninfluenced.