Leukocytic fibrinolysis in myelomonocytic leukemia

A case of myelomonocytic leukemia is described in which an increase in primary fibrinolytic activity produced a severe hemorrhagic diathesis. The leukemic cells were demonstrated to be the source of the fibrinolytic activity. Utilizing a fibrin coated slide technique, the intact leukemic cells were shown to release their fibrinolytic activity and to induce local lysis. Intact leukocytes from normal subjects and other patients with acute leukemia of varied cell types were unable to release fibrinolytic activity although in some of the leukemic preparations, increased fibrinolytic activity was demonstrated after in vitro disruption of the cells.