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

Background: Lipid transfer proteins (LTPs) are small molecules of approxima tely 10 kD that demonstrate high stability. They have recently been identif ied as allergens in the Rosaceae subfamilies of the Prunoideae (peach, apri cot, plum) and of the Pomoideae (apple). They belong to a family of structu rally highly conserved proteins that are also present in non-Rosaceae veget able foods. Objective: The aim of this study was to investigate the crossre activity to non-Rosaceae LTPs, and to study the role of protein stability i n allergenicity. Methods: Thirty-eight patients with a positive SPT to Rosa ceae fruit extracts enriched for LTP were characterized by interview and SP T. To investigate IgE cross-reactivity between Rosaceae and non-Rosaceae LT Ps, RAST and PAST inhibition as well as ELISA and ELISA inhibition were per formed, using whole food extracts and purified LTPs. Both purified natural LTPs (peach, carrot and broccoli) and Pichia pastoris recombinant LTPs (car rot and wheat) were included. Pepsin digestion was used to address the role of stability in the allergenicity of LTPs. Results: IgE antibodies to Rosa ceae LTPs reacted to a broad range of vegetable foods, including Gramineae (cereals), Leguminosae (peanut), Juglandaceae (walnut), Anacardiaceae (pist achio), Brassicaceae (broccoli), Umbelliferae (carrot, celery), Solanaceae (tomato), Cucurbitaceae (melon), and Actinidiaceae (kiwi). Binding and inhi bition studies with purified natural and recombinant LTPs confirmed their r ole in this cross-reactivity. Many of these crossreactivities were accompan ied by clinical food allergy, frequently including systemic reactions. Anti body binding to LTP was shown to be resistant to pepsin treatment of whole extract or purified LTP. Conclusion: LTP is a pan-allergen with a degree of cross-reactivity comparable to profilin. Due to its extreme resistance to pepsin digestion, LTP is a potentially severe food allergen. Copyright (C) 2000 S. Karger AG, Basel.