Identification of peroxidase-1 and beta-glucosidase as cross-reactive wheat allergens in grass pollen-related wheat allergy

Abstract

BackgroundSome patients with wheat-dependent exercise-induced anaphylaxis (WDEIA) or wheat allergy showed negative ω-5 gliadin-specific IgE test and high level of grass pollen-specific IgE. It was presumed that these patients developed allergic reaction upon cross-reaction of their IgE antibodies raised against grass pollen allergens to wheat allergens. This study aimed to clarify clinical characteristics and wheat allergens of this phenotype of WDEIA/wheat allergy, which were tentatively diagnosed as grass pollen-related wheat allergy (GPWA). MethodsA total of six patients with GPWA were enrolled, and controls were 17 patients with grass pollen allergy but no episode of wheat allergy, and 29 patients with other wheat allergies: 18 with conventional WDEIA and 11 with hydrolyzed wheat protein allergy. Sensitization to wheat proteins was determined by basophil activation test (BAT). IgE-binding proteins in wheat flour were identified by immunoblotting followed by mass spectrometry. Wheat allergen-specific IgE tests were established by CAP-FEIA system. ResultsAll the six patients with GPWA were sensitized to water-soluble wheat proteins in BAT and IgE-immunoblotting, and peroxidase-1 (35 kDa) and beta-glucosidase (60 kDa) were identified as specific IgE-binding wheat proteins. The binding of patient IgE to these proteins was inhibited by pre-incubation of patient sera with grass pollen. The peroxidase-1- and beta-glucosidase-specific IgE tests identified three and four of six patients with GPWA, respectively, but only two of 29 controls, indicating high specificity of these tests. ConclusionsPeroxidase-1 and beta-glucosidase are specific wheat allergens for GPWA among grass pollen allergy and other types of wheat-induced food allergies.