Altered pattern of differentiation and proliferation of HL-60 promyelocytic leukemia cells in the presence of leucocyte conditioned medium

Abstract

We have examined the response of HL-60 cell line to leucocyte conditioned medium (LCM), as a source of colony stimulating activity, in vitro. HL-60 cells exhibited initially increased proliferation, as assessed by tritiated thymidine incorporation and the rate of increase of viable cell counts, in response to added LCM. Cells cultured in the presence of LCM also exhibited partial differentiation with a myelomonocytic morphologic appearance and the acquisition of strong reactivity with alpha napthyl acetate esterase staining. Cells cultured in the presence of both DMSO and LCM underwent initial stages of differentiation more rapidly than with DMSO alone, but the appearance of terminally differentiated myeloid cells was delayed and cells acquired a macrophage-monocytic appearance.