Inhibition of c-kit Ligand/Steel Factor by Antibodies Reduces Survival of Lethally Irradiated Mice

Abstract

AbstractSurvival after irradiation with LD100/30 (radiation dose lethal to 100% of mice in 30 days) is based on recovery of impaired hematopoietic function. Our previous studies using antibodies to interleukin-1 receptor (IL-1R), tumor necrosis factor (TNF), and IL-6 demonstrated that endogenous production of these three cytokines is required for untreated mice as well as mice protected with lipopolysaccharide (LPS), IL-1, or TNF to survive lethal irradiation. In this report we show that anti–c-kit ligand/steel factor (SIF) antibody similarly abrogates LPS- and IL-1–induced radioprotection. Furthermore, administration of this antibody to unmanipulated mice increased LD50/30 radiation lethality from 50% to 100%. Such an effect was not obtained using anti–IL-3, anti–IL-4, or anti–granulocyte-macrophage colony-stimulating factor antibody. Thus, like IL-1, TNF, and IL-6, SIF is required for survival from lethal irradiation.