Fibrinolytic Activity of Leucocytes in Smears of Bone Marrow and Peripheral Blood

Abstract

A cytochemical method for studying fibrinolytic (proteolytic) activity in specified white cells in blood and bone marrow smears has been developed and the spontaneous fibrinolytic activity at pH 6.0 and 7.65 as well as the activity of a plasminogen‐like proenzyme were studied. These fibrinolytic enzymes appeared in the granulocytic and monocytic series; their activity depending upon the maturation stage. The enzymes appear in promyelocytes, reach the highest activity in metamyelocytes and in band cells and then gradually decrease during maturation. No significant differences between mature neutrophils, eosinophils and basophils were observed. Megakaryocytes, erythroblasts, erythrocytes and lymphocytes were devoid of significant fibrinolytic activity. Some implications of these findings are discussed.