ANTIGENICITY OF COW'S MILK PROTEINS IN TWO ANIMAL MODELS

Abstract

Antigenicity of proteins found in cow's milk is age dependent. This is primarily due to infants possessing a more permeable intestinal wall than that in adults. Thus infants may acquire cow's milk allergy during their first year of life. While milk antigen specific IgE may cause allergy in susceptible subjects, there is some evidence indicating that milk antigen specific IgG may play some role in chronic disease development. The puropose of this study was to determine the antigenicity of cow's milk proteins in two animal models and to recommend the more sensitivie one, as an evaluation tool, to assess the antigenicity of a poteintial hypoallergenic formula. A crude extract of cow's milk was injected either to young male rabbits or BALB/C mice in four doses. Pure standard proteins of cow's milk were also injected to separate groups of animals to use their anti sera in later stages. The polyclonal pooled serum was then used to evaluate the antigenicity of the extract by indirect enzyme-linked immunossorbeni assay (LEISA). and Western blotting. Both the rabbit and BALB/C murine mode! demonstrated strong ELISA titres against casein and BSA proteins. However, the rabbit model also had a high antibody response against beta-lactoglobulin (/Mg). The lowest antibody response was found against alpha-kictalbumin («-la) in both animal models and no response against immunoglobulins (Igs) in either model. In Western blotting, rabbit antiserum showed four bands («-la, /Mg, caseins and BSA) compared to two bands (caseins and BSA) for mouse antiserum. Considering the allergenicity of these proteins in genetically prone subjects, it may be wise to exclude food sources of caseins as well as major whey proteins (BSA), from the diet of infants with a family history of atopy during the first year of life. The rabbit hyperimmunization model was more sensitive than the murine mode! in detecting antibodies against milk proteins. Thus, the rabbii model should be employed when evaluating the antigenicity of a hydro lysate formula.