Protection of Spleen Tissue of γ-ray Irradiated Mice against Immunosuppressive and Oxidative Effects of Radiation by Adenosine 5′-Monophosphate

The immune system is very sensitive to radiation. This study revealed that adenosine 5′-monophosphate (5′-AMP) increased the DNA contents of the spleen and the spleen index of irradiated mice. Moreover, the exogenous 5′-AMP could significantly repair the ultra-structure of the damaged spleen through transmission electron microscopy. When indicators of the mouse immune system were assessed, the flow cytometry and enzyme-linked immunosorbent assay (ELISA) revealed that the administration of exogenous 5′-AMP could reduce the apoptosis in the splenic cells. It could also regulate the transition of cells towards S phase, increase the proportion of CD4(+) and CD8(+) cellular subsets, and enhance the secretion of interleukin-2 (IL-2), IL-4, IL-10, and interferon-γ (IFN-γ). These effects were associated with a decrease in oxidative stress, as evidenced by changes in superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), reduced glutathione (GSH), and malondialdehyde (MDA) levels of spleen tissues. These results suggested that exogenous 5′-AMP could repair the damaged spleen, increase the spleen index, and regulate the cell cycles and apoptosis. There was an increase in the production of various cytokines and play a protective role on the immune system of irradiated mice by dynamically adjusting the REDOX balance.