Food-dependent exercise-induced anaphylaxis: a report of two cases and determination of wheat-gamma-gliadin as the presumptive allergen

Water/salt-insoluble wheat proteins have been identified as the most freque nt allergenic foodstuffs in patients with food-dependent exercise-induced a naphylaxis (FDEIA) in Japan. However, the specific allergenic proteins in w heat-dependent exercise-induced anaphylaxis have not been well defined. Cha llenge testing, skin testing and a fluoroenzyme immunoassay were used for d iagnosis in two patients suspected by history of having wheat-dependent exe rcise-induced anaphylaxis. Gel chromatography and IgE immunoblotting follow ed by N-terminal amino acid sequencing were used to identify the allergenic wheat protein. The challenge test revealed that both patients had FDEIA. T he skin tests and the immunoassay results suggested that wheat gluten was t he allergen in both patients. Gel chromatography of wheat gluten revealed t hat the antigens had molecular weights ranging from 40 to 250 kDa. IgE immu noblotting and subsequent N-terminal amino acid sequencing revealed that wh eat-gamma -gliadin was the antigen predominantly bound by IgE in the two pa tients.