Leukocyte anticoagulant with myelogenous leukemia

Abstract This is a case of subacute myelogenous leukemia in a man who had a bleeding diathesis which was attributed to a leukocyte anticoagulant. The presence of the anticoagulant was first suggested by a significant prolongation of the silicone clotting time and was neutralized in vitro by phospholipid. An assay for the anticoagulant activity was developed and the results in this patient compared with assays in other subjects with chronic and acute leukemia. The assay clearly indicated a "twentyfold" increase in activity. The anticoagulant persisted after therapy even when the number of circulating leukocytes was reduced to 20,000 per cu mm. A "blastic" relapse of the leukemia was associated with a striking increase in anticoagulant activity. The marked leukopenia which developed following therapy with cystosine arabinoside resulted in the disappearance of the anticoagulant activity. To our knowledge this is the first such case to be documented. The studies suggest that leukocyte anticoagulants should be investigated in patients with leukemia who exhibit bleeding in the absence of thrombocytopenia or specific clotting factor deficiencies.