Introduction: In the present study, the radioadaptive role of the immune system induced by low dose (LD) was investigated for its in vivo protective activity.
Materials and methods: Quantitative analysis of cytokine gene expression was assessed for their in vivo activity in BALB/c mice. To evaluate the adaptive response induced by LD on the mice spleen lymphocyte, the cytokine interleukin (IL)-4, interferon (IFN)-γ, and transforming growth factor (TGF)-β expression was measured by a real-time quantitative polymerase chain reaction. To verify the radioadaptive effect of LD, animals were preirradiated at 10 cGy from a 60 Co source and then challenge dose at 200 cGy was delivered. Independent sample student's t-test was employed to compare cytokine gene expression in radioadaptive (10 + 200 cGy), LD (10 cGy), high-dose (HD, 200 cGy), and control groups of animals.
Results: Following the HD, the cytokine gene expression of IFN-γ, IL-4, and TGF-β was significantly decreased compared to the control group (P = 0.0001). However, TGF-β expression was also decreased significantly in the LD and adaptive groups compared to the control group (P = 0.0001). IFN-γ/IL-4 ratio in the adaptive group was significantly decreased compared to the HD group (P = 0.0001).
Conclusion: These results indicate that the immune system plays an important role for radioadaptive response induction by LD radiation to adjust the harmful effects of HD irradiation.
Keywords: Gene expression profiling; immune system; low-dose ionizing radiation; radioadaptive response.