Effects of whole body irradiation in mice treated with C. parvum

Abstract

We have investigated the effect of whole body irradiation (WBI) upon the survival of Corynebacterium parvum ( C. parvum)-treated CBA mice. Applied to mice 7 days after C. parvum WBI with 350–950 rad of X-ray killed more C. parvum-treated than -untreated mice. The number of endogenous hematopoietic colonies determined either at 9 days of irradiation or at the time of death of mice was greater in C. parvum-treated mice than in mice irradiated only. Using the exogenous spleen colony assay, it was found that CFUs from the spleen of mice treated with C. parvum were more sensitive to irradiation than the CFUs from the spleen of normal mice, Leucopenia caused by irradiation was equally severe in both groups of mice. However, a decrease in the number of erythrocytes was more pronounced in mice treated with C parvum and irradiation than in those given irradiation alone. Possible reasons for the increased radiosensitivity of C. parvum-treated mice as well as the relevance of these findings to tumor immunotherapy are discussed.