Maize-induced allergy: each plant a different reaction?

Cereals are the most important crops in the world. For the majority of the world’s human population, cereal-based foods constitute the most important source of energy and other nutrients. In the poorest parts of the world starchy foods, including cereals, may supply 70% of total energy. Although a number of cereal species are grown for food worldwide, only three - maize, wheat and rice (respectively, 883, 704 and 722 million tonnes in 2011) - together account for over 85% of the total production (FAOSTAT- http://faostat.fao.org/site/567/DesktopDefault.aspx?PageID=567#ancor). Maize is present in a wide range of foods (bread, breakfast cereals, corn snacks, corn flour, polenta, popcorn). Maize variation may be categorized based on the quality, quantity and pattern of endosperm composition in the kernel. Maize types are generally divided in: flint, dent, flour, pop, sweet and pop corn. Maize allergy can occur after the ingestion of maize or maize derivatives, or by the inhalation of maize flour or pollen. Recently, some papers were published on maize allergy. However, the factors that may influence allergen production are still unknown. Considering that proteins are the elicitors of the majority of allergic food reactions, it would be expected that different cultivars may induce different allergic reactions. Actually, some authors have already reported an high heterogeneity in the distribution and quantification of several already known plant allergens among different cultivars. In this study we aimed to contribute to the characterisation of maize flour allergens via proteomic tools (SDS-PAGE and 2-D gel electrophoresis followed by Western blot) trying to understand if natural proteomic differences, between maize varieties, may conduct to different allergic reactions among maize-allergic individuals. In order to accomplish this goal we have tested plasma IgE reactivity from four maize-allergic individuals against four different protein fractions (albumin, globulin, glutelin and prolamin) of three different maize cultivars. We have observed that maize cultivars have different proteomic profiles inducing different allergic reactions in the tested individuals. We could identify 19 different maize IgE-binding proteins, 11 of which unknown to date. Five of these 11 proteins, were already identified as potential allergens in other organisms. Moreover, we found that most (89.5%) of the 19 identified potential maize allergens could be related to stress. These results lead us to conclude that, like the proteome, plant allergenic potential varies with genotype and have also the potential to be highly influenced by environmental stress.