Intact Milk Protein Research Articles

EVALUATION OF HYPOALLERGENICITY OF VARIOUS INFANT FORMULA USING TNFα RELEASED FROM MONONUCLEAR CELLS OF COW'S MILK ALLERGIC CHILDREN.

We have recently shown that the peripheral blood mononuclear cells of infants with active cow's milk allergy (CMA) -but not those of tolerant infants- secreated high amounts of TNFα, when stimulated specifically with intact milk proteins. TNFα was also shown to alter the intestinal epithelial integrity. In the present study, we used the TNFα test to compare the reactivity of mononuclear cells to intact milk proteins, unprocessed infant formula, extensively hydrolyzed whey or casein formula, soya-based formula and an amino acid-based formula. Methods: blood samples were collected just before a late milk challenge from 25 cow's milk allergic infants who were maintained on a cow milk free diet for several months. Peripheral blood mononuclear cells (PBMC) were isolated and cultured at 106 cells/ml for 24 hours without stimulation, or in the presence of intact cow milk proteins (βlactoglobulin, α-lactalbumin, casein, 50μg/ml of each) or various infant formula containing extensively hydrolyzed whey proteins or casein, soya proteins or an amino-acid based formula. TNFα was assayed in culture supernatants. Results: According to clinical observations, 18 children had a positive milk challenge: in these children, unstimulated PBMC secreted low amounts of TNFα (129±34 pg/ml) compared to PBMC stimulated with intact milk proteins (693±77 pg/ml, p<0.0001) or with unprocessed formula (727±67. p<0.0001). According to the TNFα test, among the infant formula tested, the amino acid-based formula Neocate behaved as the less allergenic (TNFα =105±38 pg/ml, not different from unstimulated condition). The other hypoallergenic milk or soya-based formula induced an intermediate secretion ranging from 155±36 pg/ml (Nutramigen) to 572±102 pg/ml (Pregomine). These results indicate that the TNFα release test is a useful and sensitive test reflecting the reactivity of peripheral mononuclear cells to food antigens, that can be considered as relevant in measuring the hypoallergenicity of infant food formula.

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. (J A LLERGY C LIN I MMUNOL 1995;96:365-74.)