母牛分枝杆菌对实验性老年肺结核的免疫保护作用

Immunoprotective effect of Mycobacterium vaccae on aged mice with experimental tuberculosis

目的:探讨母牛分枝杆菌菌苗对实验性老龄小鼠肺结核的免疫保护作用.方法:老龄C57BL/6J小鼠30只,随机法分为3组:无免疫保护组(C组),母牛分枝杆菌菌苗预防组(M组),卡介苗(BCG)预防组(B组),分别在0wk给予生理盐水0.1mL,母牛分枝杆菌菌苗22.5μg,BCG0.1mg皮内注射.4wk后将浓度为5×105/mL的H37Rv标准菌株0.2mL经小鼠尾静脉给予攻毒.感染6wk后处死小鼠,流式细胞仪测定小鼠外周血T淋巴细胞亚群,观察肺脏肺泡巨噬细胞内结核分枝杆菌数及肺组织病理学分析.结果:M组和B组的CD4+T淋巴细胞、CD4+/CD8+比值分别为(48.81±3.10,3.84±0.37),(48.08±3.72,4.16±0.24)均较C组(38.97±3.03,3.25±0.26)显著升高(P<0.01).而M组CD4+/CD8+比值则低于B组(P<0.05).M组和B组肺脏肺泡巨噬细胞内结核分枝杆菌数分别为(2.3±0.5),(2.7±0.6),较C组(5.4±0.9)显著降低(P<0.01).组织病理学显示M组和B组肺脏结核病变以增殖性结核结节为主,无坏死结节;C组肺脏则以淋巴细胞结节、坏死结节为主.结论:母牛分枝杆菌菌苗可增强CD4+T淋巴细胞活性,对实验性老龄小鼠肺结核有较好的保护作用.

AIM： To explore the immunoprotection of Mycobacterium vaccae against pulmonary tuberculosis in the experimental aged mice. METHODS： Thirty aged C57BL/6J mice were randomly divided into 3 groups： the non-immunoprotective group （group C）, the Mycobacterium vaccae preventative group （group M）, and the Bacillus Calmette-Guerin （BCG） protective group （group B）. All the subjects were injected subcutaneously 0.1 mL physiological saline, 22.5 μg Mycobacterium vaccae, and 0.1 mg BCG respectively at week 0. Four weeks later, 0.2 mL standard vaccine of H37Rv at the concentration of 5 × 10^5/mL was injected through the lateral tail vein to attack. Six weeks after the infection, the mice were killed. The flow cytometer was used to test the peripheral blood T lymphocyte subsets of the mice and to count the amount of Mycobacterium tuberculosis in the alveolar macrophages. The histopathological changes were analyzed. RESULTS ： CD4^＋ T lymphocytes and CD4^＋/CD8^＋ were （48.81±3.10, 3.84 ±0.37） and （48.08 ±3.72, 4. 16 ± 0.24） respectively in group M and B, significantly higher than those in group C （38.97±3.03, 3.25 ±0.26, P〈0.01）. However, the ratio of CD4^＋/CD8^＋ of group M was lower than that in group B （ P 〈 0. 05 ）. The amount of Mycobacterium tuberculosis in the alveolar macrophages were （2.3± 0.5 ） and （ 2.7 ±0.6 ） respectively in group M and B, significantly lower than that in group C（ 5.4±0.9, P 〈 0.01 ）. The histopathological examination showed that the tuberculosis in group M and B was mainly proliferative without necrosis; the tuberculosis in group C was mainly lymphocytic and necrotic. CONCLUSION： Mycobacterium vaccae can enhance the activity of CD4^＋ ＋ T lymphocyte and prevent the pulmonary tuberculosis of aged mice.