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目的了解不同时间给予细菌内毒素对过敏性哮喘小鼠炎症反应的免疫调节作用。方法将60只小鼠随机分成4组,分别为模型组(Der f)、对照组(生理盐水)、实验A组(致敏前LPS+ Der f)、实验B组(致敏后LPS+Der f),观察肺组织病理学变化并进行支气管肺泡灌洗液(BALF)细胞计数与分类,ELISA法检测小鼠BALF与脾细胞培养液中IL-4、IL-5、IFN-γ、IL-12及血清中特异性IgE、IgG2a水平。结果与模型组比较,实验A组的BALF中炎细胞总数、嗜酸性粒细胞(EOS)、IL-4、IL-5显著降低,而IL-12显著升高(P均<0.05),血清中特异性IgE(sIgE)显著降低,而特异性IgG2a(sIgG2a)显著升高(P均<0.05);与哮喘组比较,实验B组仅BALF中IL-4水平显著升高(P<0.05)。结论致敏前LPS能显著抑制过敏性哮喘的炎细胞浸润并下调T_H2型免疫反应,而致敏后LPS未显示此功能,提示LPS致敏前给予对过敏性哮喘的发生有保护作用。
Objective To understand the immunomodulatory effects of bacterial endotoxin administered at different times on the inflammatory response in allergic asthmatic mice. Methods Sixty mice were randomly divided into 4 groups: model group (Der f), control group (saline), experimental group A (pre-sensitized LPS + Der f), experimental group B (sensitized LPS + Der f ). The pathological changes of lung tissue were observed and the numbers and classification of bronchoalveolar lavage fluid (BALF) were counted. The levels of IL-4, IL-5, IFN-γ and IL-12 in BALF and spleen cells And serum specific IgE, IgG2a levels. Results Compared with model group, the total number of inflammatory cells, eosinophils (EOS), IL-4 and IL-5 in BALF in experimental group A were significantly decreased, while IL-12 was significantly increased in experimental group A Specific IgE (sIgE) was significantly decreased, whereas specific IgG2a (sIgG2a) was significantly increased (all P <0.05). Compared with the asthma group, IL-4 level in BALF was significantly increased in experimental group B (P <0.05). Conclusions LPS before sensitization can significantly inhibit the infiltration of inflammatory cells in allergic asthma and down-regulate T_H2-type immune response. However, LPS does not show this function after sensitization, suggesting that pre-sensitization with LPS has a protective effect on the development of allergic asthma.