Studies on the allergenicity of cow's milk. I. The allergenic properties of alpha-casein, beta-lactoglobulin and alpha-lactalbumin.

It seems apparent from the present study that each of the McMeekin-Gordon protein fractions of milk is immunologically homogeneous. Of the three fractions, beta-lactoglobulin is the most allergenic, while alpha-lactalbumin and alpha-casein are of a much lower order of allergenicity. While sensitization by parenteral injection is artificial and may not thus apply strictly to natural sensitization to milk through ingestion, the data indicate that lactoglobulin is the dominant allergen of the three studied. Heretofore, lactalbumin has been considered the major protein in the production of milk allergy. The present studies furnish evidence against the lactalbumin fraction as the potent allergen in clinical practice and evidence in favor of the lactoglobulin fraction as the allergen responsible for the majority of cases of milk allergy.