Identification of a Candidate IgE-Binding Maize Protein in a Patient With Corn-Dependent Exercise-Induced Anaphylaxis: A Case Report

Corn-dependent exercise-induced anaphylaxis (food-dependent exercise-induced anaphylaxis [FDEIA]) is rare, and its causative allergens remain poorly defined. Here, we report a case of corn-dependent FDEIA and investigate candidate IgE-binding proteins using immunological and proteomic analyses. A 13-year-old boy with a history of buckwheat allergy developed recurrent anaphylaxis during exercise after ingesting corn-containing foods. An exercise challenge after ingesting 272 g of sweet corn reproduced the symptoms and confirmed the diagnosis. Corn-specific IgE was 3.72 UA/mL, and skin prick testing was positive. IgE immunoblotting revealed patient-specific bands at ~45 and 60 kDa. Two-dimensional immunoblotting and mass spectrometry identified globulin-1S (GLB1) and other proteins as candidate IgE-binding proteins in this patient. Sequence analysis revealed significant local sequence similarity between maize GLB1 and buckwheat Fag e 5 within the second cupin domain. These findings identify GLB1 as a candidate IgE-binding protein in this patient with corn-dependent FDEIA. Although sequence similarities were observed between maize GLB1 and buckwheat Fag e 5, their immunological and clinical significance remains unclear, and further studies are required to determine whether cross-reactivity exists.