Specific IgE Determination to Epitope Peptides of ω-5 Gliadin and High Molecular Weight Glutenin Subunit Is a Useful Tool for Diagnosis of Wheat-Dependent Exercise-Induced Anaphylaxis

Abstract

Wheat ω-5 gliadin and a high m.w. glutenin subunit (HMW-glutenin) have been reported as major allergens in wheat-dependent exercise-induced anaphylaxis. A simultaneous detection of specific IgE to epitope sequences of both proteins is considered to be a reliable method for diagnosis of wheat-dependent exercise-induced anaphylaxis. However, the IgE-binding epitope of HMW-glutenin remains unknown. The aim of this study was to determine the IgE-binding epitopes of HMW-glutenin to establish a useful system of identifying patients with wheat-dependent exercise-induced anaphylaxis. For determination of IgE-binding epitopes of HMW-glutenin overlapping peptides were synthesized and reactivities of IgE Abs in the sera of patients to those peptides were analyzed. Three IgE-binding epitopes, QQPGQ, QQPGQGQQ, and QQSGQGQ, were identified within primary sequence of HMW-glutenin. Epitope peptides, which include IgE-binding sequences of ω-5 gliadin and a HMW-glutenin, were synthesized and peptide-specific IgE Abs were measured by CAP-System fluorescent enzyme immunoassay. Twenty-nine of 30 patients with wheat-dependent exercise-induced anaphylaxis had specific IgE Abs to these epitope peptides. None of the 25 sera from healthy subjects reacted to both epitope peptides. Twenty-five patients with atopic dermatitis who had specific IgE to wheat and/or gluten had very low or nonexistent levels of epitope peptide-specific IgE Abs. These results indicated that measurement of IgE levels specific to epitope peptides of ω-5 gliadin and HMW-glutenin is useful as an in vitro diagnostic method for the assessment of patients with wheat-dependent exercise-induced anaphylaxis.

About the role and underlying mechanisms of cofactors in anaphylaxis

“…This most prevalent subform of FDEIA, termed 'wheat-dependent exercise-induced anaphylaxis' (WDEIA), was characterized in detail by Palosuo et al (26). Later, it was demonstrated that in most WDEIA patients, conventional tests to verify sensitization to wheat remain without reaction (27), but IgE …”

Analysis of Food Allergen Structures and Development of Foods for Allergic Patients

“…Although various foods (including shellfish, celery, hazelnuts, peanuts, soy, peas, and bananas) have been associated with FDEIA, the most frequently reported cause of these reactions appears to be wheat. 23,24) Wheat-dependent, exerciseinduced anaphylaxis is not as rare as previously thought, but is a rather poorly recognized disorder. Although the mechanisms by which exercise provokes reactions in food-or wheat-dependent, exercise-induced anaphylaxis remain unclear, the gliadin fraction is thought to be an allergen.…”

“…29) As other allergens, thioredoxin, 19) lipid transfer protein, 20) acyl-CoA oxidase, 30) peroxidase, 31) and fructose-bisphosphate aldolase 32) were identified. 8,21) In addition, the epitope structures of gliadin in patients with FDEIA 24) and celiac disease 33) have been recently reported.…”

“…Although the mechanisms by which exercise provokes reactions in food-or wheat-dependent, exercise-induced anaphylaxis remain unclear, the gliadin fraction is thought to be an allergen. 23,24) In the following sections, I focus on wheat allergens that cause atopic dermatitis.…”

Degradation of Wheat Epitope Peptides for Atopic Dermatitis and Exercise-Induced Anaphylaxis by Microbial Proteases

“…from ω-5 gliadin 4 and QQPGQ etc. from high molecular weight (HMV) glutenin 5 . The proteases from germinated wheat seeds hydrolyzed wheat gliadins and glutenins 14 , as well as the epitopes of gliadins and glutenins for atopic dermatitis 8 .…”