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

Abstract

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.