Lipid transfer protein: A pan-allergen in plant-derived foods that is highly resistant to pepsin digestion

Background: Lipid transfer proteins (LTPs) are stable and highly conserved proteins of around 10 kD. They have recently been identified as allergens i n fruits of the Rosaceae family. Objective: The aim of this study was to in vestigate whether the highly conserved structure of LTPs justifies a design ation as a true pan-allergen, and to study the role of protein stability in allergenicity. Methods: Thirty-eight patients with a positive skin prick t est to Rosaceae fruit extracts were characterized by interviews and skin pr ick tests. To investigate IgE cross-reactivity between Rosaceae and non-Ros aceae LTPs, RAST and PAST inhibition as well as ELISA and ELISA inhibition were performed, using whole food extracts and purified natural and recombin ant LTPs. To address the role of protein stability in the allergenicity of LTP, fruit extracts and LTPs were digested with pepsin. Results: IgE antibo dies to Rosaceae LTPs cross-reacted with a broad range of non-Rosaceae vege table foods. Inhibition studies with purified natural and recombinant LTPs confirmed the role of LTP in this cross-reactivity. Many of the patients wi th this type of cross-reactive IgE antibodies had a clinical food allergy. In contrast to the typical birch Rosaceae cross-reactive patients, the oral allergy syndrome was frequently accompanied by more severe and systemic re actions. IgE reactivity to LTP was shown to be resistant to pepsin treatmen t of the allergen. Conclusion: LTP is a true pan-allergen with a degree of cross-reactivity comparable to profilin. Due to its extreme resistance to p epsin digestion, LTP is a potentially severe food allergen. Copyright (C) 2 001 S. Karger AG. Basel.