Analysis of the pollen allergen content of twelve olive cultivars grown in Portugal

Olive pollen presents intercultivar variability as regards to its antigenic and allergenic composition. In this study, we report the presence of differences among the SDS-PAGE pollen protein profiles of twelve Portuguese olive cultivars. Though most soluble proteins from these extracts seemed similar, three bands of about 18, 20 and 22 kDa presented sharp differences in intensity among the cultivars analyzed. The dissimilarity of patient’s sera reactivity to these protein extracts and the presence of several allergens already characterized (Ole e 1, Ole e 2, Ole e 5 and Ole e 9) in the extracts were also investigated. Epidemiological data indicated that 53.3 % out of the 428 patients analyzed with reactivity to pollen extracts, presented specific IgE levels to Olea europaea. A representative number of these sera were assayed in immunoblotting experiments. The cultivars ‘Galega’ and ‘Conserva de Elvas’ displayed low reactivity to the sera of atopic patients, whereas the extracts corresponding to the cultivars ‘Cobrançosa’, ‘Ascolana’ and ‘Verdeal de Serpa’ led to higher IgE reactivity. The use of antibodies to the allergens Ole e 1, Ole e 2, Ole e 5 and Ole e 9 in immunoblotting experiments also allowed cultivar discrimination. The cultivar ‘Verdeal de Serpa’ presented the highest Ole e 1, Ole e 5 and Ole e 9 allergen loads but the lowest Ole e 2. ‘Carrasquenha’ was the second cultivar in terms of the higher allergen content. Oppositely, the lowest allergen loads were those of the cultivars ‘Galega’ and ‘Conserva de Elvas’ coincidentally with their low IgE reactivity. These data may help interpret physiological differences in pollen performance for successful olive fertilization and, moreover, to better define future strategies for allergy diagnosis and treatment by specific immunotherapy.