Effects of histone fractions on induction of differentiation of cultured mouse myeloid leukemia cells

Mouse myeloid leukemic cells (M1) could be induced to differentiate into macrophage-like and granulocyte-like cells by a lysine-rich, histone H1 fraction (10 to 100 microgram/ml). The differentiated M1 cells expressed phagocytic and lysozyme activity and were macrophage-like and granulocyte-like cells. The differentiation-inducing activity of histone H1 was found in histone H1 fractions isolated from calf thymus, rat liver, and mouse leukemia M1 cells. Histone H2A and H2B fractions did not induce differentiation of M1 cells at concentrations of 10 to 100 microgram/ml but did induce differentiation at a high concentration (200 microgram/ml). The histone H3 fraction, poly-L-lysine and poly-L-arginine, inhibited induction of differentiation of M1 cells.