Low doses of radiation induce systemic production of cytokines: possible contribution to leukemogenesis.

Experiments were conducted to explore the possible effect of low-dose irradiation on cytokine production in mice. SJL/J and C57BL/6J mice were exposed to 3 Gy and 4 Gy respectively. At various time intervals thereafter, lung-conditioned media, bone-marrow-conditioned media and sera were collected. Interleukin-6 and macrophage-colony-stimulating-factor activities were tested. Interleukin-6 in lung-conditioned media from both strains was found to be significantly induced by irradiation. Macrophage-colony-stimulating-factor activity was greatly enhanced in sera of irradiated SJL/J mice as well as in bone-marrow-conditioned media of both strains. The kinetics of the radiation-induced interleukin 6 and macrophage-colony-stimulating-factor activity differed in the 2 strains. SJL/J and C57BL/6J mice have been previously shown to be susceptible to low-dose-radiation-induced leukemia. The coleukemogenic effects of both cytokines in 3 different models of experimental leukemogenesis is demonstrated.