Objective To observe the effects of chronic arsenic exposure on tissues (liver ,spleen and other tissues) and immune cells (macrophage and T cells) of rats . Methods 20 rats were randomly divided into control group and low ,middle and high concentration of arsenic . The general conditions and changes in body weight of rats were observed during 12 weeks during which time the rats were fed with ar‐senic . The histological damage in liver ,spleen and other tissues were examined with H‐E staining . The phagocytosis of peritoneal macrophages was measured by neutral red method . The percentage of T lym‐phocytes were identified by flow cytometry . Results Rats exposured to high concentrations of arsenic showed abnormal gestures and behaviors and weight loss compared with the control group (P<0 .05) . Histopathological data showed tissue inflammation with arsenic exposure . The phagocytosis of peritoneal macrophages was significantly decreased in rats with high concentrations of arsenic exposure ( P<0 .05) compared with the control group . The percentage of CD3+ T cells and the ratio of CD4+ /CD8+ T cells were lower (P<0 .05) . Conclusion The tissues are damaged with chronic arsenic exposure in rats while the immune function is impaired possibly by effects on the function of macrophages and T lymphocyte sub‐sets in rats .%目的：观察慢性砷暴露对大鼠肝、脾、脑及巨噬细胞、T细胞的影响。方法20只大鼠随机分为对照组和低、中、高浓度染砷组。灌胃给药喂养大鼠12周，观察大鼠的一般情况和体质量变化；取肝、脾等组织行H‐E染色制备切片，观察组织形态学变化；中性红法测定光密度值（OD）检测腹腔巨噬细胞吞噬功能；流式细胞仪检测T淋巴细胞亚群。结果慢性高浓度砷暴露大鼠个别出现姿势和行为异常；染砷组和对照组大鼠体质量比较，有不同程度的下降（P＜0．05）；染砷组各组织切片可见不同程度的炎性细胞浸润；高浓度染砷组大鼠腹腔巨噬细胞吞噬中性红实验OD值明显低于对照组（ P＜0．05）；中、高浓度染砷组外周血CD3＋ T 细胞比例均低于对照组（P＜0．05），低浓度染砷组大鼠外周血CD4＋／CD8＋ T细胞比值高于对照组（P＜0．05），高浓度染砷组CD4＋／CD8＋比值低于对照组（P＜0．05）。结论慢性砷暴露对大鼠组织具有损害作用，并可能是通过影响巨噬细胞功能和T淋巴细胞亚群比例影响大鼠免疫功能。
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