Possible role of elevation of glutathione in acquisition of enhanced immune function of mouse splenocytes exposed to low-dose γ-rays

The relation between induction of an increased glutathione level and the enhanced immune functions, including proliferative response and natural killer (NK) activity, of mouse splenocytes by a low dose of γ-rays was investigated. Glutathione level in mouse splenocytes significantly increased 2 h after whole-body γ-ray irradiation at 0.5 Gy, peaked at 4 h and thereafter, decreased almost to the initial (0 h) level within 12 h after irradiation. A significant enhancement of Con A-induced proliferation was recognized in the splenocytes from the whole-body-irradiated animals obtained at post-irradiation between 2 and 6 h. NK activity was also enhanced at the same time periods after the irradiation. Addition of glutathione to splenocytes obtained from normal mice enhanced both Con A-induced proliferative response and NK activity in a dose-dependent manner. These enhancements were completely blocked by buthionine sulfoximine, a specific inhibitor of the de novo pathway of glutathione synthesis. These results suggest that induction of endogenous glutathione synthesis in splenocytes after low-dose γ-ray irradiation is partially responsible for the appearance of enhanced immune function.