目的：评估早期应用草分枝杆菌F.U.36注射液干预治疗对哮喘小鼠CD4⁺CD25⁺调节性T细胞（Treg）和Th17细胞平衡的影响，探讨草分枝杆菌的免疫调节作用。方法：将30只雌性BALB/c小鼠随机分为对照组、哮喘组和草分枝杆菌治疗组（治疗组），每组10只。通过注射和雾化吸入鸡卵蛋白（OVA）制备哮喘模型；治疗组于第1次致敏前2周腹腔注射草分枝杆菌F.U.36注射液0.57?μg，隔日1次，共3次；对照组以生理盐水代替致敏液。所有小鼠于末次激发后24 h处死，取小鼠左肺组织作病理切片观察炎症改变；同时利用流式细胞仪检测各组小鼠脾单个核细胞CD4⁺CD25⁺ Treg细胞、Th17细胞占CD4⁺T细胞的百分比；酶联免疫吸附试验（ELISA）检测各组小鼠血清和支气管肺泡灌洗液中细胞因子IL-10、IL-17的表达水平。结果：哮喘小鼠脾单个核细胞CD4⁺CD25⁺ Treg细胞百分比及IL-10的表达水平较对照组明显降低（P<0.05），Th17细胞的百分比及IL-17表达水平较对照组明显增高（P<0.05）；治疗组小鼠CD4⁺CD25⁺ Treg细胞百分比及IL-10表达水平较哮喘组明显升高（P<0.05），而Th17细胞百分比及IL-17表达水平较哮喘组明显降低（P<0.05）。结论：早期应用草分枝杆菌F.U.36干预性治疗哮喘小鼠，可增加CD4⁺CD25⁺ Treg细胞的数目并促进IL-10的产生，同时抑制Th17细胞的表达及IL-17的产生。

OBJECTIVE: To evaluate the effect of early intervention with Mycobacterium phlei F.U.36 injection on the balance of CD4+CD25+ regulatory T cells and Th17 cells in asthmatic mice, and to investigate the immunomodulatory effect of Mycobacterium phlei F.U.36. METHODS: Thirty female BALB/c mice were randomly divided into three groups: normal control (n=10), asthma model (n=10) and Mycobacterium phlei F.U.36 treatment groups (n=10). A mouse model of asthma was prepared by injection and aerosol inhalation of chicken ovalbumin in the asthma model and Mycobacterium phlei F.U.36 treatment groups, while mice in the normal control group were given normal saline instead. The treatment group was intraperitoneally injected with Mycobacterium phlei F.U.36 (0.57 μg, once every other day) three times in the first two weeks after the first sensitization. All mice were sacrificed at 24 hours after the last challenge. Left lung tissues of these mice were obtained and made into sections for observation of inflammatory changes. The percentages of CD4⁺CD25⁺ regulatory T cells and Th17 cells in CD4⁺ T cells among splenic mononuclear cells were determined by flow cytometry. The levels of interleukin (IL)-10 and IL-17 in serum and bronchoalveolar lavage fluid were measured using ELISA. Results Compared with the normal control group, the asthma model group had significantly decreased percentages of CD4⁺CD25⁺ regulatory T cells and IL-10 levels (P<0.05) and significantly increased percentages of Th17 cells and IL-17 levels (P<0.05). Compared with the asthma model group, the Mycobacterium phlei F.U.36 treatment group had significantly increased percentages of CD4⁺CD25⁺ regulatory T cells and IL-10 levels (P<0.05) and significantly decreased percentage of Th17 cells and IL-17 levels (P<0.05). Conclusions Early intervention with Mycobacterium phlei F.U.36 can promote development of CD4⁺CD25⁺ regulatory T cells and production of IL-10 and inhibit generation of Th17 cells and production of IL-17 in asthmatic mice.