Allergy to cows' milk is an important and frequent cause of cows' milk protein-intolerance in infants. Many infants within days of birth are fed cows' milk or cows' milk-based formula feeds. It is thought desirable to have a test available that would indicate the allergenic potency per os of milk formulae and of milk substitutes intended for infant feeding.
Such a test, based on the finding that guinea-pigs drinking cows' milk become anaphylactically sensitized to milk proteins, is described. After drinking pasteurized milk for only 4 days, 88% of guinea-pigs were susceptible to fatal anaphylaxis on intravenous challenge on the 22nd day; drinking milk for 8 days resulted in 100% of guinea-pigs becoming sensitive to fatal anaphylaxis. Following milk drinking for 7 days, a subsequent interval of 7 days was required before anaphylactic sensitivity could be shown in 100% of animals. With this information the effect of heat on the per os allergenic potency of cow's milk could be examined; likewise the allergenic potency of supposedly hypo-allergenic infant feed formulations.
Pregestimil induced no anaphylactic sensitivity even after 37 days of drinking, and no anaphylactic antibodies, detectable by PCA, were formed to the milk proteins β-lactoglobulin and casein. In contrast, AL110 likewise drunk by guinea-pigs for 37 days resulted in 90% fatal anaphylactic reactions in animals challenged with the same product. Anaphylactic antibodies were found to casein but not to β lactoglobulin.
Comminuted Chicken and Prosobee (a soya milk), two alternative ‘hypo-allergenic’ cows' milk substitutes, rendered approximately 50% guinea-pigs anaphylactically sensitive to the product fed, but neither product stimulated cross-reactive anaphylactic antibodies to either casein or β-lactoglobulin as tested by PCA.
There is some indirect evidence that results of the guinea-pig test are relevant to responses in infants with cows' milk protein intolerance.