A case of allergy to beer showing cross-reactivity between lipid transfer proteins

Background: Lipid transfer proteins (LTPs) are highly conserved proteins present in a broad spectrum of fruits and vegetables that might represent a novel plant panallergen. Objective: To demonstrate that LTP is an important allergen in beer and that beer LTP cross-reacts with LTP from botanically unrelated plant-derived foods. Methods: Serum from a patient with clinical allergy to both beer and Rosaceae was studied for IgE reactivity to LTP to several vegetable foods by PAST, ELISA, immunoblot, and inhibition studies. Results: Patient's serum showed a strong IgE reactivity to LTP purified from peach peel, carrot, and broccoli, and to a 10 kD protein in both apple and peach immunoblots, whereas no reactivity to birch cross-reactive allergens such as Bet v I, profilin, or carbohydrates was found. In inhibition studies, preabsorption of serum with apple, walnut, hazelnut, peanut, corn, and rice caused a fall of 97%, 20%, 66%, 91%, 94%, and 93%, respectively, of its reactivity to peach LTP. Beer PAST fell from 1.8 IU/mL to <0.1 IU/mL when a patient's serum was preabsorbed with recombinant carrot LTP. Conclusions: LTP is a relevant allergen in beer. Beer LTP may cross-react with LTP from several other plant-derived foods.