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

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 adult-onset 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 IgE-mediated 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 gamma-gliadin and omega 5-gliadin were the most important major allergens. Other major allergens include alpha/beta-gliadin, HMW glutenin, and possibly alpha-amylase inhibitor or LWM glutenin. Gamma-gliadin sensitization was found in all WA patients (4/4), while omega-5 gliadin was found in all WDEIA patients (11/11) from ELISA. Conclusion: Wheat gamma-gliadin and omega-5 gliadin are major wheat allergens among adult-onset wheat allergy patients in Thailand. Component-resolved diagnosis using gamma-gliadin might be helpful in high suspicion of wheat allergy.