Residual antigenicity of hypoallergenic infant formulas and the occurrence of milk-specific IgE antibodies in patients with clinical allergy.
BACKGROUND: Milk protein hydrolysates are frequently used in milk substitutes for children with cow's milk allergy. However, cases of hypersensitivity to commercially available hypoallergenic infant formulas based on milk protein hydrolysates have been reported. OBJECTIVE: Our purpose was to determine the immunologic response of milk protein-specific IgE and IgG in the serum of patients allergic to cow's milk against four commercially available hypoallergenic milk protein hydrolysates and eight infant formulas. METHODS: Antibody levels in patients' serum and milk protein-specific residual antigenicity of the hypoallergenic products were determined by indirect and competitive ELISA. RESULTS: Patients allergic to cow's milk had IgE and IgG antibodies to several protein fractions of cow's milk; intraindividual and interindividual variation in the concentrations of these antibodies was considerable. In general, IgE and IgG residual antigenicity of individual milk proteins in the hypoallergenic products was lower compared with that of the intact milk protein, but immunoreactive epitopes could still be detected in all products. Their number varied considerably among the individual milk proteins and also differed among products. CONCLUSIONS: The individual sensitization pattern of the patient allergic to cow's milk and the milk protein-specific residual antigenicity might be considered as possible laboratory predictors of adverse reactions to hypoallergenic products. Their determination could be a useful preclinical screening test for pediatricians to select a formula adapted to the individual patient.