Clinical Characteristics and Proposed Wheat-Cofactor Challenge Protocol with a High Diagnostic Yield in Adult-Onset IgE-Mediated Wheat Allergy

Background: IgE-mediated wheat allergy in adults can be childhood or adulthood onset. Adult-onset wheat allergy has been reported, but data on clinical characteristics and practical food challenge protocols are scarce. Objective: We aimed to describe the clinical characteristics of adult-onset wheat allergy, laboratory results, and outcomes of a modified 3-day challenge protocol using a combination of aspirin, wheat, and exercise. Patients and Methods: Patients with histories compatible with adult-onset wheat allergy were recruited from Siriraj Hospital, Thailand. Clinical history, skin prick tests (SPTs), and specific IgE (sIgE) levels were ascertained. Patients with no food challenge contraindications were asked to volunteer for wheat challenge. A modified 3-day protocol using 300 mg of acetylsalicylic acid, 60-75 g of wheat flour, and exercise was used for confirmatory diagnosis of conventional wheat allergy (WA) and wheat-dependent exercise-induced anaphylaxis (WDEIA). Results: Thirty-three patients were recruited. The mean age of onset was 29.7 years (SD 10.5). SPTs yielded positivity rates of 9.1%, 84.8%, and 81.8% in commercial wheat, in-house gliadin, and in-house glutenin extracts, respectively. sIgE yielded a positivity rate of 61% and 88% in wheat and omega 5-gliadin, respectively. Eighteen patients underwent oral wheat challenges. Of these, 17 patients (94.4%) had positive challenges leading to definite diagnoses of WA (35%), and WDEIA (65%). One WDEIA patient developed hypotensive anaphylaxis in the protocol. Conclusion: WDEIA was the most common phenotype. Our modified 3-day protocol could differentiate WA and WDEIA and yielded a high positivity rate (94.4%). It should be used cautiously as severe reactions can occur.