Production of interleukin 6 and its relation to the macrophage differentiation of mouse myeloid leukemia cells (M1) treated with differentiation-inducing factor and 1α,25-dihydroxyvitamin D 3

Abstract

We have studied the production of interleukin 6 (IL-6) and its relation to the macrophage differentiation in murine myeloid leukemia cells (M1). As has been reported, differentiation-inducing factor (D-factor), 1α,25-dihydroxyvitamin D 3 [1α,25(OH) 2D 3], and recombinant IL-6 similarly induced differentiation of M1 cells into macropahges. The three compounds also induced mRNA expression of IL-6 in M1 cells. M1 cells treated with D-factor or 1α,25(OH) 2D 3 produced biologically active IL-6, but the amounts of IL-6 secreted into culture media did not appear to be enough to induce differentiation of M1 cells. Furthermore, simultaneous addition of anti-IL-6 antibody did not suppress the differentiation of M1 cells induced by D-factor or 1α,25(OH) 2D 3. These results show that IL-6 production is an essential property associated with the macrophage differentiation of M1 cells, but it may not be responsible for the D-factor- and 1α,25(OH) 2D 3-induced differentiation.