IFN-γ和IL-4抗卡氏肺孢子虫感染作用的研究

目的　研究细胞因子IFN γ和IL 4的抗卡氏肺孢子虫感染作用。　方法　分别用IFN γ或IL 4基因敲除的C5 7BL 6小鼠 (各 15只作为动物模型 )与未经基因敲除的C5 7BL 6小鼠 (15只作感染对照组 ) ,以密切接触的方式 ,使小鼠自然感染卡氏肺孢子虫 ;同时设非感染组 15只小鼠作阴性对照。分别于 3、5和 7wk后观察各组小鼠肺内虫体数量、肺部CD4+ 、CD8+ T细胞反应以及血清中卡氏肺孢子虫特异性IgG抗体滴度。分析基因敲除鼠对卡氏肺孢子虫的易感性。　结果　IFN γ基因敲除小鼠肺内虫体数量明显高于IL 4基因敲除小鼠 (P <0 .0 5 )和对照组小鼠 ,而IL 4基因敲除小鼠肺内虫体数量与对照组无显著性差异 (P >0 .0 5 )。T细胞亚群分析表明 ,两种基因敲除小鼠的CD4+ 和CD8+ T细胞反应曲线与感染度呈正相关。而IgG抗体滴度 ,3组接触感染鼠均逐渐呈不同程度上升。　 结论　IFN γ在小鼠抗卡氏肺孢子虫中起重要作用 ,但缺少IL 4基因的小鼠对肺孢子虫感染的影响不明显。

The Role of IFN-

Objective To investigate the role of cytokines interferon gamma (IFN γ) and interleukin 4 (IL 4) in host defense to Pneumocystis carinii infection. Method Two different murine models (IFN γ or IL 4 gene knockout C57BL/6 mice,15 mice each strain) were contagiously infected with P.carinii by cohousing with P.carinii positive mice for 3,5,7 weeks as well as 15 gene un knockout C57BL/6 mice for infection control group. Another 15 non contagious C57BL/6 mice were as the normal control group. The number of P.carinii ,the CD4 + and CD8 + T cells, and specific IgG were detected. Results The number of P.carinii differed in different groups of mice cohabited with P.carinii infected mice. The number of the organisms in the lungs of IFN γ knockout mice increased significantly ( P < 0.05),showed a slight increase in the lungs of IL 4 knockout mice as well as the gene un knockout mice ( P > 0.05). The CD4 +and CD8 + T cells response was in parallel to the burden of cysts in the lungs but specific lgG increased gradually in 3 groups after co housing. Conclusion IFN γ is important in host for defense from P.carini infection. Absence of IL 4 does not affect the resistance of mice against P.carinii infection.