A probiotic lactobacillus was discovered from lactobacilli of the Lactobacillus genus independently isolated from human adult feces. The probiotic lactobacillus was selected from other bacterial strains for: (1) being highly resistant to gastric acid/bile acid； (2) having a high promoting activity on IL-12 production from mouse derived spleen cells and a high Th1/Th2 balance-improving effect； (3) having a high ability to inhibit the production of antigen-specific IgE induced by intraperitoneally administering ovalbumin to BALB/c mice； (4) having a high ability to inhibit the production of antigen-specific IgE induced by orally administering a food antigen to C57BL/6N mice； (5) having a high Natural Killer cell-activating ability； (6) having a high IL-12 production-promoting activity on spleen cells and mesenteric lymph node cells derived from mice immunized with ovalbumin and a high Th1/Th2 balance-improving effect； and (7) having a high ability to suppress eosinophilia induced by a cedar pollen-extracted antigen. This discovery led to the completion of the present invention.本發明由獨自分離自成人糞便的Lactobacillus屬乳酸菌中，選拔出符合(1)具有高度胃酸、膽汁酸耐受性；(2)具有促進小鼠脾臟細胞產生IL－12之活性及改善Th1/Th2平衡之效果；(3)具有高度抑制BALB/c小鼠卵白蛋白(ovalbumin)腹腔投與時誘導產生抗原專一IgE之功效；(4)具有高度抑制對C57BL/6N小鼠經口投與食物抗原時誘導產生抗原專一IgE之功效；(5)具有高度活化自然殺手(nature killer)細胞的能力；(6)具有促進卵白蛋白免疫的小鼠脾臟細胞及腸間膜淋巴節細胞之IL－12產生的活性，以及改善Th1/Th2平衡之效果；(7)能高度抑制杉樹花粉萃取抗原所誘發增生的嗜酸性白血球(eosinophil)，等條件的菌株，其結果發現一種益生菌乳酸菌能符合上述所有條件，本發明於是完成。
