Antigenicity for Humans of Cow Milk Caseins, Casein Hydrolysate and Casein Hydrolysate Fractions

Cow milk casein consists of several fractions each of which have different structure and differing antigenicity. The aim of the study was to investigate the capacity of cow milk casein, casein fractions, casein hydrolysate and its fractions to bind human IgG antibodies (antigenicity). Whole cow milk, bovine casein, α-casein native and dephosphorylated, β- and κ-casein, further a casein hydrolysate and its fractions were incubated in a IgG-ELISA assay with sera from five patients with cow milk intolerance and a pooled control serum from milk drinking healthy individuals. In healthy controls, predominantly β-caseins, both commercial and chromatographically separated, contained the strongest antigenic epitopes. In milk intolerant infants, however, κ-casein along with β-caseins was the strongest antigen. The antigenicity of the casein hydrolysate compared to nonhydrolysed casein was reduced down to 18.5 and 41.8 % measured with patient and control sera, respectively. There were traces of intact protein in the hydrolysate. Antigenicity of the casein hydrolysate fractions reached only 24 to 44 % of the antigenicity of the whole hydrolysate. Although their antigenicity roughly correlated with their molecular weight, only negligible differences among particular fractions were found