Study of IgE antigenic relationships in hypersensitivity to hydrolyzed wheat proteins and wheat-dependent exercise-induced anaphylaxis.

Background: Wheat is involved in different forms of respiratory, food and contact allergy. The IgE of patients generally reacts with various flour proteins. It is not known if antigenic relationships could explain some of these reactions and if proteins could be involved in different pathologies.

Methods: Two sera were selected as representative of patients with either wheat-dependent exercise-induced anaphylaxis (WDEIA) or hypersensitivity to hydrolyzed wheat proteins (HHWP). Their IgE specificity was studied with wheat, barley and rye proteins, using immunoblot, and immunoblot inhibition with recombinant gamma-3 hordein. This protein was chosen for its cross-reactivity with omega-5 gliadin, a major allergen in WDEIA.

Results: The IgE from both sera strongly reacted with natural and recombinant gamma-3 hordein but displayed different patterns of reactivity with wheat, barley and rye proteins. Those from the WDEIA patient showed expected reactions with omega-5 gliadin, gamma-35 and gamma-75 secalins, but also with wheat low-molecular-weight glutenin subunits (LMW-GS), and not with C hordeins. On the contrary, IgE from a HHWP patient reacted with C hordeins, various omega gliadins, and gamma-75 secalin, but very weakly with gamma-35 secalin and LMW-GS. Recombinant gamma-3 hordein inhibited strongly but not totally the WDEIA patient's IgE binding to prolamins. No such inhibition could be observed for the HHWP patient's IgE.

Conclusions: At least part of the reactions of prolamins with the IgE from the WDEIA patient was due to antigenic homologies. The occurrence of cross-reacting carbohydrates was unlikely. These common IgE epitopes were not involved in the pathology of the HHWP patient.