中文摘要：

目的观察活的/热致死发酵乳杆菌对牛乳β-乳球蛋白（BLG）致敏小鼠Th1/Th2细胞平衡、血清抗体水平及T淋巴细胞亚群数量的影响,探讨其缓解过敏反应的作用。方法用牛乳BLG和弗氏佐剂的混合液腹腔注射诱发Balb/c小鼠致敏,建立动物过敏模型。将实验动物随机分为空白组、致敏组、活的与热致死发酵乳杆菌组。采用ELISA法测定各组小鼠血清总IgE和BLG特异性IgE含量。体外分离培养各组小鼠脾淋巴细胞,采用ELISA法检测细胞上清液中Thl型细胞因子（IL-12、IFN-γ）和Th2型细胞因子（IL-4）的水平,采用流式细胞术检测脾淋巴细胞中CD3＋、CD4＋和CD8＋的百分含量。结果与致敏组相比,活的/热致死发酵乳杆菌组小鼠的IFN-γ/IL-4比值（代表Thl/Th2细胞平衡）显著增高（P〈0.05）;血清总IgE和BLG特异性IgE水平显著降低（P〈0.05）;脾淋巴细胞中的CD4＋细胞比例升高,CD4＋/CD8＋比值得到优化。特别是热致死的发酵乳杆菌组抑制IL-4分泌的效果显著优于活菌组（P〉0.05）,且该组的抗体水平和CD4＋/CD8＋比值与空白组相比无差异（P〉0.05）。结论发酵乳杆菌干预可改善小鼠的BLG过敏症状,其作用可能与促进Thl占优势的Thl/Th2细胞平衡,阻断IgE分泌及平衡T淋巴细胞亚群数量相关。

英文摘要：

We aim to investigate the effects of live/dead Lactobacillus fermentum on the Th1/Th2 cell balance,antibody production and T lymphocyte subsets of milk BLG-sensitized mice.We firstly set up a food allergic experimental rat model by intraperitoneally injecting of the mixture of milk BLG and Freund＇s adjuvant.Then rats were randomly divided into 4 groups： blank group,food allergy group,live and heat-killed L.fermentum groups.The total IgE and BLG-specific IgE contents in the serum of rats were measured with ELISA;splenic lymphocytes were isolated and cultured in vitro,the levels of Thl type cytokine（IL-12,IFN-γ） and Th2 type cytokine（IL-4） were detected by ELISA;the lymphocyte subgroups in the spleen were analyzed by flow cytometry.We found that the IFN-γ/IL-4 value which represents the Th1/Th2 cell balance both increased significantly in live and dead L.fermentum groups compared with those of food allergy group（P 0.05）,but the serum levels of total and BLG-specific IgE decreased significantly（P 0.05）.In addition,the percentage of CD4＋ T cell was increased and the ratio of CD4＋ to CD8＋ of the rats was optimized;the production of IL-4 from administered rats was significantly lower as compared to live L.fermentum,at the same time,the antibody production and CD4＋/CD8＋ ratio in heat-killed L.fermentum group showed no difference compared with the blank group（P 0.05）.Thus,we conclude that intake of L.fermentum may be effective in preventing and alleviating BLG allergic symptoms by the improvement of the Th1/Th2 cell balance toward Th1 dominance and the inhibition of IgE production and modulating splenic T lymphocyte subsets.