B-096 LTP Allergy: a descriptive study on prevalence in a population from Granada, Spain

Abstract Background Lipid transfer proteins (LTPs) are the most common cause of primary food allergy and food-induced anaphylaxis in Southern European countries (Mediterranean and Atlantic areas). They are widely distributed in the outer layer of plant-based foods as well as in the pollen of trees and herbaceous plants. Due to their biochemical and molecular characteristics, LTPs exhibit high resistance to enzymatic digestion, acidic pH, and heat, leading to immunological cross-reactivity with unrelated foods or pollens in patients sensitized to these proteins. LTPs are considered complete food allergens (Class I allergens) capable of sensitizing through the gastrointestinal tract, with peach LTP (Pru p 3) often acting as the primary sensitizer, subsequently directing the immune response towards recognizing other LTPs. The aim of this study was to determine the LTP sensitization profile and its association with food allergies in patients consulting the allergy department in our region. Methods Samples were collected from patients attending our allergy department with suspected LTP sensitization. Once sensitization was confirmed through a positive intradermal test for LTP, demographic data, clinical allergy history, and diagnostic test results were recorded. In vivo testing was conducted using intradermal skin tests, while in vitro testing involved specific IgE determination using LTP-RUO immunoblot assay strips from Euroimmun®, which include six recombinant allergens and four allergen mixtures. Results A total of 96 samples were collected, including 13 negative controls. The average patient age was 35 years, with a majority of female participants (55%). Among the specific IgE tests for LTP analyzed, 25 patients (30.1%) tested positive for all LTPs, 11 patients (13.3%) tested positive for between 1 and 5 of the studied LTPs, and 55 patients (66.3%) tested positive for more than 5. Seventeen participants (20.5%) tested negative for all LTPs but showed reactivity to aeroallergens (mainly pollen family) through intradermal skin testing. The Pru p 3 test (peach LTP), considered the primary sensitizer, was negative in 19 participants (22.9%), with no positive results for any of the other measured LTPs. We found two patients who tested negative for Pru p 3 but positive for other LTPs: one for X2 Pha v3 (green bean) and the other for both X4 Sola L (tomato) and X2 Pha v3 (green bean). Conclusion LTP sensitization in our geographic area is predominantly linked to Pru p 3 but it cannot be considered a prototypical marker of this syndrome. LTP allergy is very common in Mediterranean countries and can cause potentially life-threatening reactions. This highlights the need to understand the clinical and immunological characteristics that can help identify and prevent anaphylactic episodes in patients exposed to LTP-containing foods