The effect of erythropoietin and other factors on DNA synthesis by mouse spleen cells.

The effects of pure and crude human urinary erythropoietin, crude sheep plasma erythropoietin and other growth factors on the incorporation of labeled thymidine were studied using spleen cells from mice previously treated with phenylhydrazine hydrochloride. Erythropoietin at 400 mU/ml caused a 40-80 fold increase in the incorporation of the labeled nucleoside. The slope of the dose-response curve found for pure erythropoietin was not significantly different from that found for a crude urinary erythropoietin preparation or for crude sheep plasma erythropoietin. Colony-stimulating factor, interleukin 2, interleukin 3 and the lectin, concanavalin A were also stimulatory but at concentrations from one hundred to one million times higher than that found for erythropoietin.