Anticoagulant activity in cell homogenate of adult T cell leukemia

The hemostatic abnormality in 18 patients with adult T cell leukemia (ATL) was studied. Activated partial thromboplastin time (APTT) was slightly prolonged and prekallikrein activity was markedly low in these patients. The leukemic cell homogenate from these patients prolonged the recalcification time (RCT) of normal plasma; homogenates containing more than 3 x 10(3) cells/microliter prolonged it, although a lower cell concentration shortened it. The crude anticoagulant fraction from the gel filtration, with a molecular weight of about 34,000, prolonged RCT. The crude anticoagulant did not affect prothrombin time (PT), thrombin activity or activated X activity at any concentration, but prolonged the contact activation test, inhibited the activation of prekallikrein and prolonged RCT of Fletcher trait, Fitzgerald trait and F XII deficient plasma. These effects of ATL cell homogenate were stronger on platelet poor plasma than on platelet rich plasma. Although ATL cells had low procoagulant activity, increase of leukemic cells made anticoagulant activity predominant, might be the cause of hemostatic abnormality or amplify the bleeding tendency in patients with ATL.