Evaluation of the allergenicity of infant formulas in a guinea pig model

In the present study we evaluated the allergenicity of infant formulas using a guinea pig model. Seven groups of ten guinea pigs each maintained on a diet free of cow milk received either water or pasteurized cow milk (PCM) or a conventional cow milk infant formula (CMF) or whey hydrolysate formula (WHF) to drink. On day 37 all the animals were challenged by intravenous injection with 0.5 mL of supernatant of either PCM or WHF. The reactions to the challenge were expressed as none, mild, severe nonfatal, and fatal. A score ranging from 0 to 3 was assigned to each animal and considered in the statistical analysis; P values are expressed as comparisons to the negative water-fed control group. Animals fed WHF and challenged with WHF (group 1), showed 10% fatal reactions and 50% severe but not fatal reactions (P less than .05). When challenged with PCM (group 2), 40% showed a mild reaction. Cow milk formula-fed animals showed 10% fatal reactions and 70% severe reactions when challenged with WHF (group 3). The same challenge caused 40% severe reactions in animals fed PCM (group 4) (P greater than .05). Animals fed and challenged with PCM (group 5) showed 100% fatal reaction (P less than .01). Animals fed water showed no reaction when challenged with either WHF (group 6) or PCM (group 7). The results suggest that WHF has less anaphylactic sensitizing power than PCM and CMF.