低剂量辐射对小鼠胸腺细胞成熟、分化、凋亡和激活的影响

目的研究低剂量辐射对胸腺细胞成熟、分化、激活和细胞凋亡及有关基因蛋白表达的影响，以揭示低剂量辐射免疫增强效应的发生机理。方法采用双参数直接免疫荧光和间接免疫荧光流式细胞术，检测了低剂量辐射小鼠全身照射后胸腺细胞ＣＤ４、ＣＤ８、ＴＣＲ、ＣＤ３、ＩＬ－２Ｒ、［Ｃａ２＋］ｉ、Ｂｃ１－２、Ｂａｘ的表达和细胞凋亡。结果实验结果表明：低剂量辐射全身照射未引起ＴＳ减少和ＴＨ／ＴＳ比值上调；低剂量辐射未增加胸腺细胞凋亡，这与Ｂｃｌ－２／Ｂａｘ比值上调有关；低剂量辐射促进了胸腺细胞的成熟分化和信息传递过程。结论以上结果提示：低剂量辐射促进胸腺细胞的成熟、分化和激活，使胸腺向外周输送成熟的具有功能活性的效应性Ｔ细胞的储备增强，可能是低剂量辐射免疫增强效应的重要机理。

Effects of low dose radiation on differentiation, activation and apoptosis of thymocytes in mice

Objective\ To elucidate the possible mechanism of immunoenhancement after low dose radiation (LDR),the differentiation,activation and apoptosis of thymocytes following low dose irradiation were studied. Method\ Kunming mice were whole body irradiated (WBI) with low dose X rays.The expressions of CD4,CD8,TCR,CD3,IL 2R,(Ca 2 ) i,Bcl 2 Bax and apoptosis of thymocytes were analyzed by flow cytometry.Results\ It was found that the ratio of T H/T S showed no significant changes after LDR.Thymocyte apoptosis was not increased after LDR.The increase of Bcl 2/Bax ratio after LDR might be one of its mechanisms.LDR could expedites the process of differentiation of,and facilitate the signal transduction in,thymocytes. Conclusion\ The results indicate that the mechanism of immunoenhancement might be related to the expedition of the maturation,differentiation and activation of thymocytes,thus up regulating the capability of supplying more mature T lymphocytes to the periphery by the thymus after LDR.