Low Molecular Weight Glutenins in Wheat-Dependant, Exercise-Induced Anaphylaxis: Allergenicity and Antigenic Relationships with Omega 5-Gliadins

Abstract

Background: Adults suffering from wheat-dependant, exercise-induced anaphylaxis (WDEIA) develop IgE directed against wheat ω5-gliadins (major allergens for this allergy) and against wheat low-molecular weight glutenin subunits (LMW-GS). However, the ability of LMW-GS to trigger an inflammatory response is still unknown. It also remains to be determined if IgE from these patients bind the same epitopes on LMW-GS and ω5-gliadins or if the epitopes are independent. Methods: WDEIA patients were selected and skin prick tests (SPTs) were performed on them using commercial gluten, wheat flour extracts, prolamin fractions and a purified natural LMW-GS P42. The IgE-binding ability of natural and recombinant wheat prolamins was verified by immunoblot experiments. Cross-reactivity between LMW-GS and ω5-gliadins was studied by immunoblot inhibition experiments, using purified natural ω5-gliadin as an inhibitor. Results: Patients developed positive SPTs with natural LMW-GS fractions and/or with the purified LMW-GS P42. Natural and recombinant LMW-GS were highly reactive with patient IgE in immunoblot experiments, as was ω5-gliadin. However, differences in reactivity were evident within the LMW-GS group. Except for one recombinant LMW-GS (P73), IgE cross-reactivity between LMW-GS and natural ω5-gliadin was only partial. Conclusion: LMW-GS are able to promote local inflammation and they share common epitopes with ω5-gliadins. The nature of these epitopes is discussed. LMW-GS also carried specific epitopes, completely independent from the ω5-gliadin epitopes. Thus, LMW-GS behaved partly as independent allergens.

Wheat‐dependent exercise‐induced anaphylaxis

“…All percentages based on total gluten contents. Two recombinant LMW-GS also reacted with IgE antibodies [54] and a subsequent study confirmed the WDEIA-specific antigenicity of LMW-GS [55]. In addition to x5-gliadin, HMW-GS were shown to be the most potent allergens [53] with three predominant epitopes (QQPGQ, QQPGQGQQ, and QQSGQGQ) [49].…”

Antibody reactivity in patients with IgE-mediated wheat allergy to various subunits and fractions of gluten and non-gluten proteins from ω-gliadin-free wheat genotypes

“…It seems obvious as the ω-5 gliadin fractions act as the main allergens in WDEIA [18,[32][33][34]. However, ω-5 can be also active in other wheat allergies [21,35].…”

Development and characteristics of ω-gliadin-free wheat genotypes

“…This decrease in immunoreactivity occurred in spite of overexpression of a/b and some c-gliadin genes. a/b and c-gliadins are less allergenic than x-gliadins (Battais et al 2003;Bouchez-Mahiout et al 2010;Waga et al 2011). However, higher amounts of low immunoreactivity a/b or cgliadins might, theoretically, have a greater effect than lower-amounts of more immunoreactive x-gliadin proteins.…”