Letter | Published:

Peculiar Disorder of Plasma Thromboplastin Production


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.

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  1. 1

    Biggs, R., and Douglas, A. S., J. Clin. Path., 6, 23 (1953).

  2. 2

    Nour-Eldin, F., and Wilkinson, J. F., J. Physiol., 136, 324 (1957).

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