Esterases in acute leukemias: a cytochemical and electrophoretic study.

Specific and nonspecific esterases were extracted from various typical cytologic types of leukemic blasts and subjected to electrophoresis in polyacrylamide gel. Preparations rich in normal granulocytes and normal monocytes were analyzed in a similar manner. The results indicated the presence of specific esterase activity in normal monocytes and in myelomonocytic and histiomonocytic leukemia, and a lack of consistent differences in the electrophoretic patterns of both specific and nonspecific esterases in these leukemias. The results support the viewpoint that distinctions between myelomonocytic and histiomonocytic leukemias cannot be made with certainty, and that they may represent variants within a broad spectrum of monocytic leukemias rather than separate and distinct entities.