Rye gamma-70 and gamma-35 secalins and barley gamma-3 hordein cross-react with omega-5 gliadin, a major allergen in wheat-dependent, exercise-inducedanaphylaxis

Background Patients with wheat-dependent, exercise-induced anaphylaxis expe rience severe allergic reactions when exercising after ingestion of wheat. The major wheat allergen associated with these reactions is a omega -5 glia din, and patients following a gluten-free diet have remained free of sympto ms. Objective The aim of this study was to examine whether allergens cross-reac ting with wheat omega -5 gliadin are present in rye, barley and oats. Methods Sera from 23 adult patients with wheat-dependent, exercise-induced anaphylaxis were examined. Cereal allergens cross-reacting with wheat omega -5 gliadin were identified by immunoblot inhibition. The cross-reactive al lergens were purified by gel filtration and reversed-phase chromatography a nd submitted to amino acid sequencing. Cross-reactivity was further studied by IgE ELISA and ELISA inhibition, and in vivo reactivity by skin prick te sting. Results In immunoblotting rabbit anti-omega -5 gliadin antibodies bound to 70 kDa and 32 kDa proteins in rye and a 34-kDa protein in barley, but not t o proteins in oats. N-terminal sequencing identified these proteins as rye gamma -70 secalin, rye gamma -35 secalin and barley gamma -3 hordein, corre spondingly. In ELISA 21/23 (91%) patients with wheat-dependent, exercise-in duced anaphylaxis showed IgE antibodies to purified gamma -70 secalin, 19/2 3 (83%) to gamma -35 secalin and 21/23 (91%) to gamma -3 hordein. In ELISA inhibition omega -5 gliadin inhibited over 90% of the IgE binding of pooled patient sera to solid-phase gamma -secalins and gamma -3 hordein. Skin pri ck testing gave positive reactions to gamma -70 secalin in 10/15 (67%) pati ents, to gamma -35 secalin in 3/15 (20%) patients and to gamma -3 hordein i n 7/15 (47%) patients. Conclusion The results of this study show that gamma -70 and gamma -35 seca lins in rye and gamma -3 hordein in barley cross-react with omega -5 gliadi n, a major allergen in wheat-dependent, exercise-induced anaphylaxis. These findings suggest that also rye and barley may elicit symptoms in patients with wheat-dependent, exercise-induced anaphylaxis.