Comparative analysis of allergen genes and pro-inflammatory factors in pollen and fruit of apple varieties

Allergy to freshly consumed apple fruits is often associated to pollinosis and manifested as oral allergy syndrome (OAS). The allergenic properties of apple varieties differ greatly, spanning from low allergenic to high allergenic varieties. The knowledge of the genetic determinants for allergenicity has been of great interest in scientific community for several years, but the molecular mechanisms involved are still little understood. Here, factors putatively involved in allergenicity were investigated at biochemical and molecular level in pollen and in fruits of apple varieties differing in their allergenic potential. Among putative sensitizing factors, transglutaminase (TGase) and phospholipase A(2) (PLA(2)) were considered together with reactive oxygen species (ROS) and known apple allergen genes, with particular attention devoted to the Mal d 1 gene family, the most important one in sensitization. We found that the expression of some allergen genes and the activities of TGase, PLA(2) and ROS producing enzyme are lower in the hypo-allergenic variety 'Duren di Forli' in comparison with the high-allergenic genotypes 'Gala' and Tlorina'. These results highlight correlations among allergen expressions, enzymatic activities and apple cultivars; these data underline the possibility that some of them could be used in the future as markers for allergenicity.