Stimulatory effect of a dietary casein phosphopeptide preparation on the mucosal IgA response of mice to orally ingested lipopolysaccharide from Salmonella typhimurium.

The effect on immunoglobulin production of a commercially available casein phosphopeptide preparation (CPP-III) consisting mainly of bovine alpha s2-casein (1-32) and beta-casein (1-28) in mice that had orally ingested lipopolysaccharide (LPS) from Salmonella typhimurium was investigated. No significant difference in body weight gain was observed between the mice fed on the CPP-III-added diet and those fed on the control diet. The mice fed on the CPP-III-added diet exhibited similar serum and intestinal IgG, IgM, and IgE responses towards LPS to those fed on the control diet. In contrast, fecal and intestinal anti-LPS IgA and total IgA in mice fed on the CPP-III-added diet were significantly higher than in those fed on the control diet. Spleen cells from mice fed on the CPP-III-added diet produced larger amounts of IgA, IL-5, and IL-6 than cells from mice fed on the control diet. These results suggest that dietary casein phosphopeptide may protect a host from invasion of the intestinal mucosa by food-born pathogenic microorganisms.