Induction of differentiation of WEHI-3B D+ leukemic cells transfected with differentiation-stimulating...

Differentiation-stimulating factor (D-factor)/leukemia inhibitory factor can induce the differentiation of mouse myeloid leukemia M1 cells and also stimulate proliferation of the interleukin-3 (IL-3)-dependent cell line, DA-1a. To determine whether D-factor can induce the differentiation of leukemia cells other than M1 cells, WEHI-3B D+ mouse myelomonocytic leukemia cells were transfected with a plasmid containing mouse D-factor receptor cDNA. Expression of D-factor receptor in transfected cells was determined by binding of [125]D-factor and analyzed by Scatchard's method. The transfected cells had high-affinity D-factor receptors with a dissociation constant of 100 to 200 pmol/L and binding sites per cell varied from 67 to 1,500 among several clones. The cells expressing a high level of D-factor receptor were induced to differentiate by D-factor; about 60% of the cells exhibited the ability to reduce nitroblue tetrazolium and expression of the differentiation antigen Mac-1 (CD11b) on the cell surface increased. The effect of cytokines, which induce the differentiation of M1 cells, on the transfected WEHI-3B cells was examined. The sensitivity to oncostatin M was identical to that against D-factor in the cells of each clone. Expression of D-factor receptor in WEHI-3B cells promoted sensitivity to IL-6 and granulocyte colony-stimulating factor (G-CSF). Induction of differentiation of the cells accompanied the suppression of proliferation. Treatment of the cells with D-factor for longer than 5 days resulted in 50% inhibition of growth. These results indicate that the stimulating effect of D-factor on the differentiation of malignant myeloid cells is not unique to M1 cells.