γ射线对小鼠调节性T细胞功能及相关细胞因子的影响及其意义

调节性T细胞（regulatory T cells,Tregs）及相关细胞因子在机体免疫平衡的调节中发挥重要作用,而其在放射免疫损伤中的作用尚不明确.本实验以6Gyγ射线照射C57BL/6小鼠,于照射后1～28d不同时间,检测外周血、胸腺和脾脏Treg细胞亚群及血清中细胞因子IL-2,IL-10及TGF-γ含量的变化,以探讨其在放射免疫损伤中的作用机制.结果显示,小鼠经6Gyγ射线照射后各组织CD4＋CD25＋Treg细胞比例明显增加（P〈0.05或P〈0.01）,胸腺CD4＋CD25＋Foxp3＋Treg细胞比例于照后1d即明显增高（P〈0.01）,而在照后7d明显低于未照射组（P〈0.01）;血清抑制性细胞因子IL-10（7d）,TGF-γ（3d）含量明显增高（P〈0.05）,而IL-2浓度持续降低.本文揭示了Treg细胞及其相关细胞因子与辐射所致免疫功能受抑和免疫调节功能失衡密切相关,为进一步的辐射损伤机制研究奠定基础.

Effects and Significance of γ-irradiation on Mouse Regulatory T Cells and Related Cytokines

Regulatory T cells (Tregs) and related cytokines play important roles in the regulation of immune balance, but its role in immune damage induced by radiation is not clear. In this study, the changes of C57BL/6 mouse peripheral, thymic and splenic Tregs and contents of serum cytokines (IL-2, IL-10 and TGF-β) were analyzed at different time points post 6 Gy γ-ray radiation, in order to investigate the effects of Tregs in immune injury. The results show that the percentage of CD4⁺CD25⁺ Tregs in different organs increased significantly (P<0.05 or P<0.01) after 6 Gy γ-ray irradiation. The percentage of thymic CD4⁺CD25⁺Foxp3⁺ Tregs increased significantly (P<0.01) at 1d post radiation, but it was much lower (P<0.01) than that of the control group at 7 d post radiation. Meanwhile, the contents of suppressor cytokines of IL-10(7 d) and TGF-β (3 d) increased significantly (P<0.05), however, IL-2 decreased distinctively. In summary, our study reveals that Tregs and related cytokines are closely correlated with immunosuppression and immuno-modulation imbalance induced by ionizing radiation, and provides basis for further study on the mechanism of radiation damage.