Ig E reactivity to carbohydrate moieties of glycoproteins in wheat allergy

Abstract

RATIONALE: In current available diagnostic tests, wheat proteins do not include all the allergens derived from wheat protein fractions with different solubility. The role of whole gliadin to wheat allergy has not evaluated, yet. The carbohydrate moieties of different glycoprotein such as cross-reactive carbohydrate determinants and galactose alpha-1,3-galactose can induce IgE responses with diversity of clinical significance. In this study, we purposed to evaluate the allergenicity of gliadin to wheat allergy. Possible participation of the glycan from gliadin of wheat in their IgE-binding capacity was also investigated in children with wheat allergy.METHODS: Total IgE, wheat specific IgE, careful history taking and oral food challenge were done for 52 children. They were characterized as wheat allergy patients, wheat IgE high group, wheat positive control and negative control. SDS-PAGE and glycan detection of gliadin were evaluated. IgE binding to gliadin and deglycosylated gliadin were measured by immunoblotting and ELISA.RESULTS: Gliadin specific IgE was detected in all patients with wheat allergy and not correlated with wheat specific IgE. The range of glycan was almost overlapping with whole gliadin bands. Removal of glycan from gliadin reduced allergenicity of gliadin. In gliadin, allergenicity of glycan portion was larger in wheat allergy patients than wheat IgE high group.CONCLUSIONS: We suggest that the examination of IgE reactivity to whole gliadins are useful to diagnosis of wheat allergy. We concluded that almost all gliadins might be glycosylated and N-glycan of gliadin might have allergenicity as possible carbohydrate epitope in wheat allergy children.