Heterogeneity of banana allergy: characterization of allergens in banana-allergic patients.

Background: Banana is a frequent cause of food allergy, particularly in latex-sensitized patients.
Objective: The aim of the study was to get insights in immunoglobulin (Ig)E antibody responses of patients with a history of allergic reaction to banana but not to latex.
Methods: In four patients who complained about symptoms after banana consumption, skin prick tests (SPTs) with aeroallergens, latex, banana, avocado, and kiwi were performed. Total and specific serum IgE to birch pollen, rBet v 1 and rBet v 2, latex, banana, avocado, and kiwi were determined by the CAP method (Pharmacia Diagnostics, Uppsala, Sweden). Allergens were identified by immunoblotting with banana extract and recombinant banana profilin. Two patients underwent double-blind, placebo-controlled food challenges (DBPCFC) with banana.
Results: All patients showed a positive SPT to banana, and three were IgE-CAP positive (> or = class 2). Two patients were also sensitized (SPT and CAP) to latex, avocado, kiwi, and birch pollen. In the immunoblot these two patients' sera reacted to 32- to 34-kDa proteins, which had already been described as major banana allergens. In both patients banana allergy was confirmed by DBPCFC. The third patient also had a sensitization to avocado, but not to latex or pollen. Immunoblot analysis detected a single band at 70 kDa. The fourth patient was sensitized to birch pollen, rBet v 1 and rBet v 2, but not to latex. Immunoblot analysis in this patient's serum was positive with recombinant banana profilin.
Conclusions: The relevance of banana as a source of food allergy was confirmed in two patients by DBPCFC. In 1 of 2 patients, in whom banana allergy was not a consequence of latex sensitization, a 70-kDa protein was identified as a banana allergen, and in the other patient profilin was detected as a putative cross-reactive allergen.