Abstract
Induction of arginase activity in mouse myeloid leukemic M1 cells by treatment with recombinant human tumor necrosis factor (rH-TNF) or TNF-elicited mouse serum (TNS) were examined in vitro. M1 cells differentiated into macrophage-like cells by addition of rH-TNF or TNS. The differentiated cells expressed phagocytic function and did not grow anymore. Cytolytic effect of rH-TNF or TNS was not observed. The differentiation of M1 cells into phagocytic cells by the TNS treatment was more rapidly than that by the rH-TNF treatment though TNS contained 25-time less amounts of TNF indicating species specificity of TNF action on myeloid leukemic cells or TNS containing other differentiation factor (s). 3H-ornithine formation from 3H-arginine is catalyzed by arginase (EC, 3.5.3.1). The enzyme product increased in the M1 cell culture medium by the treatment with rH-TNF or TNS. The arginase activity statistically correlated with the appearance percentage of differentiated cells with phagocytic function. These results suggest that in vitro differentiation of M1 cells is accompanied by induction of arginase activity.
