Effect of antigen load on development of milk antibodies in infants allergic to milk.

The phenomenon that large amounts of antigen, such as are absorbed during the neonatal period, suppress the IgE response while low-dose exposure enhances it was investigated by analysing the antibody responses of infants allergic to milk according to their degree of exposure to cows'-milk protein. IgG, IgA, and IgM milk-specific antibodies in these infants and in age-matched controls were measured by enzyme-linked immunosorbent assay. Milk-specific IgE and total IgE were also measured. Children allergic to milk who were breast fed and had had minimal exposure to cows' milk had decreased titres of IgG, IgA, and IgM milk antibodies compared with infants allergic to milk who, before diagnosis, had been fed substantial volumes of cows' milk. Conversely, the infants with minimal exposure to cows' milk showed vastly increased total and milk-specific IgE antibodies compared with the milk-fed infants. These results support recent experimental evidence that appreciable amounts of allergen suppress rather than stimulate IgE production. These data may have important implications for dietary regimens in at-risk infants. The results also lend support for the role of IgE in immediate-type allergic reactions and suggest that various non-IgE immune mechanisms play a part in the aetiology of intolerance to cows'-milk protein in some children.