nutrients Article LTP Allergy Follow-Up Study: Development of Allergy to New Plant Foods 10 Years Later Diana Betancor 1 , Alicia Gomez-Lopez 1 , Carlos Villalobos-Vilda 1 , Emilio Nuñez-Borque 2 , Sergio Fernández-Bravo 2 , Manuel De las Heras Gozalo 1,3 , Carlos Pastor-Vargas 3,4, * , Vanesa Esteban 2,3,5,† and Javier Cuesta-Herranz 1,3,†   Citation: Betancor, D.; Gomez-Lopez, A.; Villalobos-Vilda, C.; Nuñez-Borque, E.; Fernández-Bravo, S.; De las Heras Gozalo, M.; Pastor-Vargas, C.; Esteban, V.; Cuesta-Herranz, J. LTP Allergy Follow-Up Study: Development of Allergy to New Plant Foods 10 Years Later. Nutrients 2021, 13, 2165. https://doi.org/10.3390/nu13072165 Academic Editors: Sara Manti, Gian Luigi Marseglia and Salvatore Leonardi Received: 15 May 2021 Accepted: 22 June 2021 Published: 24 June 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Allergy, Instituto de Investigación Sanitaria Hospital Universitario Fundación Jiménez Díaz (IIS-FJD, UAM), 28040 Madrid, Spain; diana13_b@hotmail.com (D.B.); alicia.gomezl@quironsalud.es (A.G.-L.); c.villalobosvilda@gmail.com (C.V.-V.); mheras@fjd.es (M.D.l.H.G.); j.cuestaherranz@gmail.com (J.C.-H.) 2 Department of Immunology, Instituto de Investigación Sanitaria Hospital Universitario Fundación Jiménez Díaz (IIS-FJD, UAM), 28040 Madrid, Spain; enbli7@hotmail.com (E.N.-B.); sergio.fernandezb@quironsalud.es (S.F.-B.); vesteban@fjd.es (V.E.) 3 RETIC ARADyAL, Instituto de Salud Carlos III, 28029 Madrid, Spain 4 Department of Biochemistry and Molecular Biology, Universidad Complutense de Madrid, 28040 Madrid, Spain 5 Faculty of Medicine and Biomedicine, Alfonso X El Sabio University, Villanueva de la Cañada, 28691 Madrid, Spain * Correspondence: cpasto01@ucm.es † These authors have contributed equally to this work. Abstract: Introduction: Allergy to nonspecific lipid transfer protein (nsLTP) is the main cause of plant-food allergy in Spain. nsLTPs are widely distributed in the plant kingdom and have high cross- reactivity but extremely variable clinical expression. Little is known about the natural evolution of this allergy, which complicates management. The objective of this study was to assess the development of allergy to new plant foods in nsLTP-sensitized patients 10 years after diagnosis. Methods: One hundred fifty-one patients showing specific IgE to nsLTP determined by ISAC (Thermofisher) were included. After clinical workup (i.e., anamnesis, skin test, and challenge when needed), these patients were divided into two groups: 113 patients allergic to one or more plant food (74.5%) and 38 patients not allergic to any plant food (25.1%). Ten years later, a telephone interview was conducted to check whether patients had developed additional allergic reactions to plant foods. Results: Ten years after diagnosis, 35 of the 113 (31%) plant-food-allergic patients sensitized to nsLTP reported reactions to new, previously tolerated plant foods, mainly Rosaceae/Prunoideae fruits and nuts followed by vegetables, Rosacea/Pomoideae fruits, legumes, and cereals. Five out of 38 (13.2%) patients previously sensitized to nsLTP but without allergy to any plant food had experienced allergic reactions to some plant food: two to Rosaceae/Prunoideae fruits, two to Rosaceae/Prunoideae fruit and nuts, and one to legumes. Conclusion: Patients sensitized to nsLTP developed allergic reactions to other plant foods, mainly Rosaceae-Prunoideae fruits and nuts. This was more frequent among plant-food-allergic patients than among those who had never had plant-food allergy. Keywords: nsLTP; plant-food allergy; Pru p 3; peach; nut; Rosaceae fruit; ISAC 1. Introduction Food allergy affects around 0.3% to 5.6% of the population, showing substantial geographical variation in prevalence and in terms of the culprit food [1]. Allergy to plant foods is the most common food allergy among older children and adults [1]. Nonspecific lipid transfer proteins (nsLTPs) are small, highly stable and conserved molecules involved in the plant defense against fungi and bacteria [2,3]. nsLTPs are found in high concentrations in the epidermal tissues of fruits and are the main allergens of fruits Nutrients 2021, 13, 2165. https://doi.org/10.3390/nu13072165 https://www.mdpi.com/journal/nutrients