Dietary cycloinulooligosaccharides enhance intestinal immunoglobulin A production in mice.

The purpose of this study was to elucidate the effects of dietary supplemented cycloinulooligosaccharides (CF) on the intestinal immune function and humoral immunity in BALB/c mice. The mice were orally administered with a control diet or a diet containing 5% CF for 6 weeks. The fecal IgA level, an indicator of the intestinal immune response, was increased dramatically by 5% CF feeding, and casein-specific IgA in the feces was also significantly increased. The amounts of short-chain fatty acids (SCFA) in the cecal contents and feces were significantly higher in the 5% CF group than in the control group. On the other hand, CF administration had only a slight affect on the plasma IgA and IgG levels and no effect on the plasma IgE and IgM levels. These results indicate that dietary CF up-regulated the intestinal immune response, but not the humoral immune response. Furthermore, the dose-dependent effect of CF feeding on IgA and SCFA production was examined. Significant increases in the fecal IgA and SCFA levels were observed in the mice fed with 5% CF, but not in the 1% and 2.5% CF-fed groups, indicating that the amount of CF administered was an important factor for up-regulation of the intestinal immune function.