Immunological characterization of recombinant Mal d 1, the main allergen from apple (Malus x domestica L. Borkh)

Apple-related allergy is increasing among European population. Avoidance of apple fruit consumption is the only strategy for sensitized people, with a subsequent shortage of healthy nutrients in the diet. Four different protein families, Mal d 1 to 4, determine the allergy to apple causing syndromes known as oral allergy syndrome (OAS) or gastro-intestinal/generalized syndrome (GS) in sensitized patients. With the aim to highlight the dissimilarities in the immunological response inside the Mal d 1 family, recognized as main determinant for OAS, single purified allergens were tested against sera of paediatric and adult patients suffering for both syndromes. Here, we found that Mal d 1 isoallergens showed a remarkable different allergenicity potential, thus indicating an individual pattern in each patient and a diverse sensitization between age groups. Moreover, two different allergens, Mald 2.01 and Mal d 4.01, were analyzed with the above sera. In addition to patients and allergens variability, differences in amount and localization of the allergens, detected by patient’s sera, were revealed among hypo- and hyper allergenic apple varieties, confirming the complexity of this food allergy.