该研究探讨乳双歧杆菌XLTG11对免疫功能损伤模型小鼠免疫功能的影响。采用环磷酰胺（CTX）构建小鼠免疫损伤模型，设立空白组和模型组，灌服生理盐水，阳性对照组，灌服盐酸左旋咪唑（LEV）（10 mg/kg），给药组灌服不同浓度乳双歧杆菌XLTG11（1×106、1×107、1×108、1×109 CFU），连续28 d，测定各组小鼠免疫功能相关指标。各剂量组乳双歧杆菌XLTG11可以拮抗CTX对小鼠胸腺的损伤，胸腺指数分别比模型组提高37.37%、43.43%、56.56%和84.84%（p<0.05）；增加小鼠足跖肿胀程度，足跖厚度分别比模型组提高38.24%、50.00%、55.89%和94.12%（p<0.05）；提高小肠绒毛高度，增加杯状细胞数目（p<0.05），其中1×109 CFU剂量组小肠绒毛高度提高20.82%（p<0.01），杯状细胞数目提高51.23%（p<0.01）；升高血清免疫球蛋白和细胞因子水平（p<0.05），以IgA、IL-2和TNF-α水平升高最为显著，1×109 CFU剂量组IgA水平升高20.03%（p<0.001），IL-2水平升高35.94%（p<0.001），TNF-α水平升高14.50%（p<0.05）。乳双歧杆菌XLTG11具有增强小鼠免疫功能作用，且呈剂量依赖性。该研究为益生菌保健食品开发和使用提供理论依据。

The effects of Bifidobacterium lactis XLTG11 on immune function utilizing an immunosuppressed mouse model that was constructed using cyclophosphamide (CTX) were investigated. The blank control and model groups were given normal saline, the positive control group was given levamisole hydrochloride (LEV) (10 mg/kg), and the experimental groups were given B. lactis XLTG11 at different concentrations (1×109, 1×108, 1×107, or 1×106 CFU) for 28 consecutive days; subsequently, immunological indices were measured. All mice dosed with B. lactis XLTG11 resisted CTX damage to the thymus; their thymic indices increased by 37.37%, 43.43%, 56.56%, and 84.84% (p<0.05), respectively, compared with those of the model group. Additionally, the experimental groups showed increases in plantar thickness of 38.24%, 50.00%, 55.89%, and 94.12% (p<0.05), respectively. Higher villus height and goblet cell number in the small intestines (p<0.05) were also observed, with those of the 1×109 CFU group increasing by 20.82% (p<0.01) and 51.23% (p<0.01), respectively. Moreover, elevated serum immunoglobulin and cytokine levels were detected (p<0.05). IgA, IL-2, and TNF-α levels increased the most; in the 1×109 CFU group, IgA increased by 20.03% (p<0.01), IL-2 by 35.94% (p<0.01), and TNF-α by 14.50% (p<0.05). Therefore, B. lactis XLTG11 enhanced the immune function of immunocompromised mice in a dose-dependent manner. Our findings can serve as a theoretical basis for the development and use of probiotic health foods.

黑龙江省自然科学基金项目（LH2019H106）；黑龙江省“头雁”团队