Reversal of human myeloid leukemia cells into normal granulocytes and macrophages: activity and intracellular distribution of catalase.

The activity and intracellular distribution of catalase was studied in culture human myeloid leukemia cells before and after induction of differentiation with tunicamycin. Activity of catalase was increased 5-fold in acute myeloid leukemia cells (AML) and 3-fold in chronic myeloid leukemia cells in comparison with normal granulocytes. Tunicamycin induced differentiation of HL-60 line and primary AML line characterized by increase in phagocytic cells and changes to resemble mature myeloid cells. Fc receptors were also induced in cells after tunicamycin treatment. Induction of differentiation with tunicamycin decreased high activity of catalase in cultured leukemic cells. The results of digitonin titration experiments showed that in control granulocytes and differentiated leukemic cells most of the catalase activity is present in subcellular particles distinct from mitochondria or lysosomes. In contrast, the catalase activity in undifferentiated cells is present in the same compartment as the other cytosolic markers.