Elastase activity in leukemic cells.

Elastase, a proteolytic enzyme which digests different clotting factors, has previously been isolated from monocytes, macrophages and granulocytes. In the present work, we have isolated leukemic cells from 1 patient with acute lymphoblastic leukemia (ALL) and from 6 patients with acute nonlymphoblastic leukemia. Detectable elastase activity was found in the cells from all patients with acute nonlymphoblastic leukemia and ranged from 0.016 to 0.619 mukat/l/micrograms DNA. The highest elastase activity was found in 1 patient with promyelocytic leukemia (M3), and no activity was found in the cells from the patient with ALL. It is possible that elastase-mediated proteolysis of coagulation factors is the mechanism responsible for bleeding complications which are frequent in M3.