Differences between normal and milk allergic subjects in their immune responses after milk ingestion.

In order to understand why non-atopic people do not have adverse symptoms to food antigens which enter the circulation after eating, 8 non-atopic and 10 atopic eczema- and milk-allergic subjects were challenged with milk, and the types of circulating immune complexes formed were analysed. Although the amount of beta-lactoglobulin incorporated into complexes did not differ statistically between the groups, the type of immune complex did. Of the non-atopic individuals, 5 formed IgA and 2 IgG complexes. Of the milk-allergic group, all showed a rise in at least one type; 5 formed IgA, 7 IgG, 6 IgE, and 6 formed C1q-binding complexes. Our data suggest that serum IgA is concerned in safe food antigen handling in non-atopic people, and that the differences in the type of immune complexes formed in response to antigen challenge may underlie the systemic symptoms of food allergy.