One of the well-known immunoregulatory functions of probiotics is the induction of cytokine production Given that IL-10 exerts improving effects on the diseases caused by a skew in the immune responses, it is promising to isolate an active Lactobacillus strain that can stimulate the host immune cells to generate sufficient amount of IL-10. We attempted to isolate the strains that efficiently stimulate host immune cells to produce IL-10 from traditional fermented foods in Thailand. As a result, we could isolate a lactobacillus strain TJ515 (Lactobacillus pentosus), that bore high IL-10-inducing efficiency, out of 270 Lactobacillus strains. The gnotobiotic mice associated with TJ515 were immunized with ovalbumin and alum to evaluate the effect of TJ515 on the skewed Th2/IgE response. As a result, both total IgE and OVA-specific IgE responses were minimal in the TJ515-associated mice, whereas these IgE responses were very high in the gnotobiotic mice associated with little IL-10 inducing lactobacillus isolate. The immune cells obtained from those TJ515-associated mice produced a significant amount of IL-10 by challenge with the antigen in vitro. These results presented the possibility of TJ515 as a probiotic strain to suppress Th2-skewed IgE response through induction of IL-10 production