the effect of hyperthermia on the differentiation of leukemic cell lines

treatment of human promonocytic leukemic cell line u937 with mild hyperthermia in the temperature range of 40-43°c resulted in differentiation of these cells into monocyte/macrophage-like cells in a heat dose and time dependent manner. this process was accompanied by marked morphological, functional and proliferational changes. u937 cells which normally grow in supension in the logarithmic phase of growth showed marked inhibition in proliferation after treatment with heat in comparison with controls, without significant decrease in cell viability. the clonogenicity of these cells in semisolid agar cultures was also reduced upon heat treatment. heat treatment increased the fraction of cells which could reduce nitro blue tetrazolium (nbt) and phagocytize latex particles. these data demonstrate that heat treatment can induce differentiation ofu937 cells into monocytes/macrophages and thus have possible applications in treatment of leukemia. temperatures higher than 43°c or exposures of longer than 30 minutes at such high temperatures resulted in cytotoxic effects.