Omega-5 and Gamma Gliadin are the Major Allergens in Adult-Onset IgE-Mediated Wheat Allergy: Results from Thai Cohort with Oral Food Challenge

Abstract

Background: Various clinical patterns based on routes of sensitization and sensitized allergens are reported in adult-onset IgE-mediated wheat allergy. There is still a paucity of data on IgE-bound wheat allergen profiles in wheat challenge-proven adult-onset wheat allergic cases. Therefore, we aim to identify the major sensitized allergens in Thai adultonset wheat allergic patients whose first symptom occurred after the age of 18 years despite previous tolerance. Methods: This cross-sectional pilot study recruited patients from the Thai Adult-onset IgEmediated Wheat Allergy Cohort (TAWAC). The sera of patients with mostly challenge-proven cases were selected for allergen study, including ImmunoCAP and IgE-bound gliadins along with glutenins profiles. The IgE-bound proteins were identified by liquid chromatographytandem mass spectrophotometry (LC-MS/MS). Direct binding of IgE to recombinant gliadin and glutenin was performed to confirm the results of immunoblot and LC-MS/MS. Results: Eleven wheat-dependent exercise-induced anaphylaxis (WDEIA) and 4 typical wheat allergy (WA) patients were enrolled. Serum IgE from >50% of bound proteins had a molecular weight ranging from 35 to 55 kDa in both gliadin and glutenin extracts. Further, ELISA demonstrated that γ-gliadin and ω5-gliadin were the most important major allergens. Other major allergens include α/β-gliadin, HMW glutenin, and possibly α-amylase inhibitor or LWM glutenin. Gamma-gliadin sensitization was found in all WA patients (4/4), while ω-5 gliadin was found in all WDEIA patients (11/11) from ELISA. Conclusion: Wheat γ-gliadin and ω-5 gliadin are major wheat allergens among adult-onset wheat allergy patients in Thailand. Component-resolved diagnosis using γ-gliadin might be helpful in high suspicion of wheat allergy.

Elicitors and phenotypes of adult patients with proven IgE‐mediated food allergy and non‐immune‐mediated food hypersensitivity to food additives

“…Most studies, however, have been performed in paediatric cohorts and their role in adulthood has not been completely established. For example, Tri a 19 has been suggested for wheat allergy, 27,28 whereas for other allergens, like celery, the availability of recombinant allergen diagnostics is still limited.…”

A Meta-Analysis of the Prevalence of Wheat Allergy Worldwide

“…The proteins in wheat that can cause allergic reactions, including those related to gliadin, glutenin, albumin, and globulin. Moreover, omega-5 and gamma gliadin are major allergens in adults with wheat allergy in Thailand [ 3 ]. Alpha-amylase/trypsin inhibitor family members exhibit strong IgE reactivity in wheat flour [ 4 ], and omega-5 gliadin and high molecular weight gluten are major allergens associated with wheat-dependent exercise-induced anaphylaxis (WDEIA) [ 5 ].…”