Lipid-transfer proteins are relevant allergens in fruit allergy

Allergy to apple and Prunus fruits is frequently associated with birch pollinosis, with the principal cross-reacting allergens involved being members of the Bet v 1 family. However, a major 13-kd component, nonimmunologically related to Bet v 1, has been implicated as allergen in patients allergic to Prunoideae fruit but not to birch pollen.

We sought to isolate and characterize the 13-kd allergen present in apple and peach.

Sera from patients allergic to both fruits were selected on the basis of clinical symptoms, skin prick tests responses, and specific IgE levels. Allergens were purified by reverse-phase HPLC and characterized by N-terminal amino acid sequencing, MALDI analysis, specific IgE immunodetection, and immunoblot inhibition assays.

A 13-kd protein band was recognized in crude apple and peach extracts by 9 of 10 and 10 of 10 sera from patients allergic to fruit, respectively. The isolation and characterization of the corresponding allergens allowed their identification as lipid-transfer proteins, with a molecular mass of 9058 d for the apple protein and 9138 d for the peach protein. Both purified allergens were recognized by sera from patients allergic to fruit and fully inhibited the IgE binding by the 13-kd component present in the 2 crude fruit extracts.

Lipid-transfer proteins are relevant apple and peach allergens and, considering their ubiquitous distribution in tissues of many plant species, could be a novel type of panallergen of fruits and vegetables.