The Immunoenhancing Property of a Dietary Casein Phosphopeptide Preparation in Mice

The effect on serum and intestinal IgG or IgA production of a dietary casein phosphopeptide preparation, CPP-III, mainly consisting of residues 132 of bovine αs2-casein and residues 128 of bovine β-casein, was investigated in mice. No significant difference was seen in body weight gained between mice fed a CPP-III-added diet (a mixture of 0.1 to 1.0 g CPP-III and 24.9 to 24.0 g ovalbumin as protein sources in 100 g diet) and mice fed a control diet (25.0 g ovalbumin in 100 g diet). Mice fed CPP-III-added diets exhibited a similar serum IgG response towards β-lactoglobulin injected peritoneally and ovalbumin ingested orally to those fed the control diet. In contrast, the level of serum IgA towards the proteins showed a rising tendency in mice fed CPP-III-added diets compared with those fed the control diet. The difference between the control diet group and CPP-III-added diet groups was often statistically significant. Moreover, the intestinal antigen-specific IgA and total IgA in some mice fed the CPP-III-added diet were significantly higher than those fed the control diet. The present results suggest that oral use of the casein phosphopeptide is beneficial to the enhancement of mucosal immunity.