Lipid-transfer proteins are relevant allergens in fruit allergy

Abstract

Background: 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. Objective: We sought to isolate and characterize the 13-kd allergen present in apple and peach. Methods: 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. Results: 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. Conclusion: 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. (J Allergy Clin Immunol 1999;103:514-9.)