实验性矽肺模型大鼠外周血CD4＋CD25＋Foxp3＋调节性T细胞的变化及意义

[目的]研究实验性矽肺大鼠在染尘后病情发展不同阶段外周血CD4＋CD25＋T细胞和CD4＋CD25＋Foxp3＋调节性T细胞（Treg细胞）的频率，初步探讨Treg细胞在矽肺发生发展中的可能作用。[方法]将40只健康雄性SD大鼠随机分为模型组和对照组，模型组24只，对照组16只。模型组以非暴露方式气管内一次性注入1mL石英粉尘悬液（40mg／mL）建立大鼠矽肺模型，对照组大鼠气管内一次性注入等容量的灭菌生理盐水。染尘后第7、14、21及28天分别处死6只模型组和4只对照组大鼠，用流式细胞术检测大鼠外周血CD4＋CD25＋细胞及Treg细胞的百分率。[结果]第7天，急性肺泡炎期间，模型组CD4＋CD25＋T细胞和Treg细胞较正常对照组频率明显降低（P〈0．05）；第14天，矽性肉芽肿形成期，模型组CD4＋CD25＋细胞和Treg细胞数量回升，接近正常水平；第21天，矽性肉芽肿增多期间，模型组CD4＋CD25＋T细胞和Treg细胞频率较正常对照组略高，但差异不具有统计学意义；第28天矽性肉芽肿增多并大量纤维化期间，模型组CD4＋CD25＋T细胞和Treg细胞频率明显增加，与对照组相比差异具有统计学意义（P〈0．05）。[结论]Treg细胞可能在维持免疫耐受和矽肺的发生发展中发挥重要作用。

Changes and Significance of CD4+CD25+Foxp3+ Regulatory T Cells in Peripheral Blood in Experimental Silicotic Rat Model

[ Objective ] To investigate changes and significance of CD4＋CD25＋Foxp3＋ regulatory T cells （ Treg ceils ） in peripheral blood of silica exposed rats at different stages, and to explore the role that Treg may play in the development of silicosis. [ Methods ] Forty healthy male SD rats were randomly divided into the model and the control groups, with 24 rats in model group and 16 rats in control group. One miniliter silica suspension （ 40 mg/mL ）was administrated via intratracheal instillation while equal amount of saline was instilled to the rats of control group. Animals were sacrificed on the 7th, 14th, 21st and 28th day after instillation. The levels of CD4＋CD25＋ T ceils and Treg cells were analyzed by flow cytometry. [ Results ] During the stage of acute alveolitis （ on the Th day ）, the levels of CD4＋CD25＋T cells and Treg cells in silicotic rats were significantly lower than those in control group （ P 〈 0.05 ）. During the development stage of silicotic granuloma（ on the14th day ）, the levels of CD4＋CD25＋T ceils and Treg cells in silicotic rats increased slightly and approached to those of control group. On the 21st day, the levels of both CD4＋CD25＋T cells and Treg cells were higher than those in control group, but without statistical significance. During the stage of more silicotic granuloma and fibrosis（ on the 28th day ）, both of the levels significantly increased with statistical significance（ P 〈 0.05 ）. [ Conclusion ] Treg cells may play an important role in the maintenance of immune tolerance and the development of silicosis.