氡暴露对大鼠淋巴细胞的免疫毒性

Immunotoxicity of Radon Exposure on Rat Lymphocytes

[目的]通过研究氡暴露对大鼠胸腺、脾脏、外周血及骨髓淋巴细胞的损伤作用,探讨氡对大鼠免疫功能的影响,为探索氡致机体免疫损伤的可能机制提供实验资料。[方法]将15只健康雄性Wistar大鼠随机分成3组,每组5只,动物整体暴露于HD-3型多功能生态氡室,累积受照剂量分别达200工作水平月(WLM)和400WLM后,腹主动脉采血,胸腺、脾脏制成单细胞悬液,分离股骨取骨髓。采用五分类血液分析仪进行骨髓、外周血细胞计数及分类。采用荧光探针检测不同剂量氡暴露组淋巴细胞内活性氧(ROS)、游离钙离子浓度、线粒体膜电位(MMP)水平的变化。采用碘化丙啶(PI)染色后,观察脾脏、胸腺淋巴细胞周期及凋亡率。[结果]200WLM氡暴露组大鼠外周血淋巴细胞数为(6.84±1.40)×109/L,高于对照组的(3.34±1.10)×109/L(P<0.01),2剂量组骨髓淋巴细胞计数均明显增加(P<0.01);200WLM组胸腺淋巴细胞ROS高于对照组(P<0.01),骨髓、外周血淋巴细胞MMP低于对照组(P<0.01),脾脏、胸腺淋巴细胞钙离子浓度明显升高(P<0.01);与对照组比较,胸腺细胞G0/G1期细胞比例明显降低,而S期细胞比例显著升高,脾脏细胞则相反;200WLM氡暴露组胸腺细胞凋亡率为(1.63±0.46)%,高于对照组的(0.69±0.64)%(P<0.05),而400WLM氡暴露组未见明显改变。[结论]氡及其子体可暴露对大鼠免疫细胞和免疫功能产生毒性作用。

[ Objective ] To explore the adverse effects of radon and its daughters on lymphocytes in thymus, spleen, peripheral blood （PB）, bone marrow （BM）, and provide experimental data for mechanistic investigation on radon-induced immune damage in rats. [ Methods ] Fifteen male Wistar rats were divided to three groups with 5 rats in each group： 1 control group and 2 exposure groups. The exposed rats were placed in a HD-3 multifunction ecological radon chamber at a cumulative radiation dose of 200 or 400 working level months （WLM）. At the end of the exposure, the spleen and thymus of the rats were aseptically excised, and PB ＆ BM were collected to obtain single cells. The total number and proportion of cells in BM and PB were counted. The level of reactive oxygen species （ROS）, intraeellular free calcium concentration, mitochondrial membrane potential （MMP）, cell cycle, and the apoptosis in lymphocytes were also detected by fluorescence probe. [ Results ] The 200WLM radon exposure resulted in a statistically significant increase of lymphocytes in the PB in comparison with the control group [ （6.84 ± 1.40） × 109/L vs. （3.34 ± 1.10） × I09/L, P〈0.01 ]; the same changes were found in the BM of the two exposure groups. The level of ROS of thymus lymphocytes in the 200 WLM group was significantly higher than that in the control group （P 〈 0.01）. In the same group, the MMP of lymphocytes in BM and PB were significantly lower, and the intracellular Ca2~ concentration of lymphocytes of spleen and thymus were significantly higher than the corresponding indices of the controls （P〈 0.01）. The G0/G1 phase of thymocytes from the 200 WLM group was reduced and the S phase was prolonged; opposite results were observed in the splenocytes with baseline of the controls. The apoptotic rate of thymocytes in the 200WLM group was （1.63 ± 0.46）%, significantly higher than that in the control group [ （0.69 ± 0.64）%, P 〈 0.05 ]; but the same effect was not observed in the 400WLM group. [ Conclusion ] Radon and its daughters may cause toxic effects on immune cells and immune function of rats.