Leuconostoc mesenteroides strain NTM048 has been shown to have intestinal IgA-inducing ability. In this study, we investigated the immunostimulant potency of an exopolysaccharide secreted from strain NTM048 (NTM048 EPS) in vitro and in vivo in a murine model. NTM048 EPS ranges in size from 10 to 40 kDa and is speculated to be mainly composed of glucose and fructose. The in vitro study revealed that NTM048 EPS induced total and antigen-specific IgA production by Peyer's patch cells and influenced Th1 and Th2 cell-mediated response in splenocytes. Oral administration of NTM048 EPS dose-dependently induced fecal IgA production accompanied by the up-regulation of retinoic acid synthase and transforming growth factor-β receptor genes in Peyer's patch cells. Flow cytometric analysis of the splenocytes revealed an increase of the CD3+ T-cell population and the ratio of CD4+ T-cells/CD8+ T-cells. These results indicate that NTM048 EPS could enhance the mucosal barrier and influence the systemic immune response.
Keywords: Leuconostoc mesenteroides; antigen-specific IgA; exopolysaccharide; immunostimulant; systemic immune response.