Cabbage lipid transfer protein Bra o 3 is a major allergen responsible for cross-reactivity between plant foods and pollens

BackgroundFood IgE-mediated allergy to members of the Brassicaceae family has been increasingly reported.ObjectiveTo characterize cabbage—Brassica oleracea var capitata—allergy and its major allergens.MethodsA prospective study was performed, recruiting 17 patients allergic to cabbage, and control subjects. Skin prick tests and double-blind placebo-controlled food challenges were performed. A major allergen was isolated from cabbage by RP-HPLC and characterized by N-terminal amino acid sequencing and matrix-assisted laser desorption/ionization mass spectrometry analysis. Specific IgE determinations, IgE immunoblots, and CAP-inhibition assays were also performed.ResultsSkin prick test and specific IgE were positive to cabbage in all patients. Five of them referred anaphylactic reactions when eating cabbage, and in another 5 patients, cabbage allergy was further confirmed by double-blind placebo-controlled food challenge. Most of them showed associated sensitizations to mugwort pollen, mustard, and peach. A 9-kd cabbage IgE-binding protein, Bra o 3, was identified as a lipid transfer protein (LTP) with 50% of identity to peach LTP Pru p 3. Skin prick test with Bra o 3 showed positive results in 12 of 14 cases (86%). On CAP inhibition assays, Bra o 3 managed to inhibit significantly the IgE binding to cabbage, mugwort pollen, and peach. Both Bra o 3 and Pru p 3 were recognized by IgE from the patients' sera.ConclusionBra o 3, a cabbage LTP, is a major allergen in this food, cross-reacting with mugwort pollen and with other plant foods, such as peach.Clinical implicationsCabbage IgE-mediated allergy is a potentially severe condition that can present with other plant food and pollen allergies.