Serological characterization of allergens in poppy seeds

BACKGROUND AND OBJECTIVE: Poppy seeds in food can induce immediate-type allergic reactions ranging from mild local symptoms to severe anaphylactic reactions. Previous publications showed that poppy seeds cross-react with other plant-derived allergens. The IgE-binding components have not been defined so far. METHODS: We analysed sera from 11 patients with adverse reactions after ingestion of poppy seed-containing food by IgE-immunoblotting. Nine of 11 patients showed concomitant IgE binding to allergens of birch, mugwort or grass pollen in RAST-CAP, and suffered from characteristic seasonal symptoms. RESULTS: Ten of 11 patients showed IgE binding to a 45-kDa protein, 4/11 to a 34-kDa, 5/11 to a 17-kDa, 5/11 to a 14-kDa, and 3/11 to a 5-kDa component. Furthermore, individual IgE binding to proteins of 20, 25, 30 and 40 kDa proteins could be observed. Periodate treatment of blots markedly reduced the IgE binding capacity of the 40- and 45-kDa compounds, indicating the existence of IgE epitopes of the carbohydrate type. Inhibition studies indicated the presence of homologues of pollen allergens in extracts from poppy seeds, i.e. Bet v 1 and Bet v 2. CONCLUSION: The serological analysis showed IgE binding to protein and sugar components of poppy seeds. The 40- and 45-kDa allergens are glycoproteins and contain IgE binding carbohydrate moieties. Moreover, cross-reacting homologues of pollen allergens including Bet v 1 and profilin were detected in poppy seed extract.