Microwaves activate immune response and promote lymphocytes proliferation of Wistar rats

Abstract

Objective The potential effects of microwave radiation on human health have been increasingly emphasized with its widespread application in human production and daily life. This study aimed to investigate microwave radiation effects on rat spleen tissue structure and immune function. Methods Male Wistar rats weighed approximately 320 to 350 g were subjected to S band (2.856 GHz) microwave radiation for 20 minutes at an average power density of 50 mW/cm². At 0 and 7 days after exposure, the concentration of IL-1, IL-1β, IL-2, IL-4, IL-8, IL-10, TNF-α and IFN-γ in rat serum were detected by ELISA. HE staining was used to observe the structure of rat spleen. Western blotting was used to assess the expression of HSP70 and CRT in rat spleen. Additionally, mixed lymphocytes from rat spleens were isolated, and the morphology and proliferation of rat spleen mixed lymphocytes was observed after 24 hours of culture, and their proliferation was evaluated using the CCK-8 assay. Results After exposure to 50 mW/cm² for 20 minutes, rats showed an increased secretion of inflammatory factors in their serum. This was observed both in the immediately irradiated group (R-0d) and in the irradiated group observed after 7 days (R-7d). The R-0d group exhibited lower levels of IL-1 and IL-8 than the control group (C-0d), while IL-2 and IL-10 secretion was elevated. Conversely, in the R-7d group, levels of IL-1, IL-2, and IL-10 were lower than those in the C-0d group, and IL-8 levels were lower compared to the control group. TNF-α and IFN-γ levels were elevated. Structural examination of rat spleen tissue revealed no significant damage. However, compared to the control group, the irradiated groups (R-0d and R-7d) showed a significant increase and thickening of the white pulp. Additionally, the boundary between the red and white medulla in the R-7d group appeared blurred. Western blotting showed no significant difference in the expression of HSP70 and CRT between the exposed and control groups. In addition, the splenic mixed lymphocytes in the irradiated group showed a significant proliferation of cell colonies. The results of the CCK-8 assay showed that the cell viability and proliferation capacity of the irradiated group were significantly increased compared to the control group. Conclusion The immune system of rats was activated, the pattern of cytokine secretion in rat serum was altered, splenocytes proliferation was promoted, potentially triggering an inflammatory immune response after exposure to 50 mW/cm² of microwave for 20 minutes.