Does cypress pollen exposure influence sensitisation to Pru p 7 as a major allergen in peach allergy? To the editor:Gibberellin-regulated protein (GRP) was recently identified as an allergen in pollen-fruit syndrome1. Similar to peach Lipid Transfer protein (LTP) Pru p 3, peach GRP (Pru p 7) has been associated with severe allergic reactions2. In addition, Pru p 7 has been proposed as a possible major allergen in peach, in areas with high cypress pollen counts3. However, the relevance of this allergen in an area with high prevalence of Pru p 3 sensitization and high cypress pollen exposure has not been fully established.A descriptive, observational study was conducted in Hospital Clínic, Barcelona between January 2021 and August 2023. Patients diagnosed of peach allergy based on clinical history and positive skin prick test to peach were included. Clinical data as age, gender, severity of reactions (classified by oFASS-3 scoring4), other offending plant foods, and presence of cofactors were also collected. Total IgE and serum specific IgE (sIgE) to Pru p 3, Pru p 7 and peach were tested (ImmunoCAP®, ThermoFisher Scientific). In addition, the presence of both cypress pollen sensitization and pollen count data from our area were assessed. (Detailed methods-Supplementary Material).A total of 140 patients were included; 123 (87.9%) were monosensitized to Pru p 3, 10 (7.1%) were sensitized to both (co-sensitized), and 7 (5.0%) were monosensitized to Pru p 7. Their main characteristics are summarized in Table 1. Patients monosensitized to Pru p 7 were all women, showed higher levels of sIgE Pru p 7 than co-sensitized patients (p=0.15), and lower peach sIgE values than those monosensitized to Pru p 3 (p=0.001) or co-sensitized (p=0.03). Moreover, two of these patients had negative sIgE to peach.Pru p 7 monosensitized patients had similar clinical features. Almost all (6/7) presented anaphylactic reactions, and.cofactors were frequently involved (5/7), exercise being the most common (4/7). Rosaceae and citrus fruits were the most frequent culprit foods; other offending foods were apple, fig, halzenut and pear (table 2). All these subjects were also sensitized to cypress pollen.The cypress pollen count (Annual Pollen Integral, or sum of the mean daily pollen concentrations along the year) in our area (Barcelona-Bellaterra) during the study period were 17.530 pollen*day/m3 in year 2021, 8.122 pollen*day/m3 in year 2022 and 8.320 pollen*day/m3 in year 2023.Pru p 7 has recently been reported as a peach major allergen in southern France, a region geographically close to ours (north-east Spain)3. In this study, out of the five analyzed regions in France, the most represented has a cypress annual pollen count of 18,782 pollen*day/m3, comparable to our area. Interestingly, despite the similarity of the cypress pollen exposure, geographical proximity, and climatic resemblance, we have observed a different peach sensitization profile that confirms the role of LTP as a major allergen and GRP as a minor allergen in our area. This difference suggests that other factors apart from cypress pollen exposure may influence Pru p 7 sensitisation.Concerning the severity of reactions, Pru p 7 monosensitized patients exhibited more severe reactions compared to Pru p 3 and Pru p 3+Pru p 7 groups (Table 1). Conversely, the presence of cofactors was consistent across all groups.Our study observed that peach-specific IgE is a poor biomarker of Pru p 7 sensitisation as over 50% of Pru p 7 monosensitized patients had negative or very low peach-specific IgE levels. For this reason and to avoid false negative results, we recommend testing Pru p 7 in all patients with suspected peach allergy and those with citric fruit-related reactions.Finally, our results suggest that others plant foods different from those previously described 5 could be triggering reactions in GRP allergic patients. Future studies are needed for a better understanding of the clinical pattern of GRP food allergy and the potential cross reactivity of this protein among plant foods not taxonomical related, to define a Gibberellin-regulated protein syndrome that would present very similar characteristics, but not identical, to LTP syndrome.REFERENCESTuppo L, Alessandri C, Pomponi D, et al. Peamaclein–a new peach allergenic protein: similarities, differences and misleading features compared to Pru p 3. Clin Exp Allergy. 2013;43(1):128-140. doi:10.1111/cea.12028.Inomata N, Okazaki F, Moriyama T, et al. Identification of peamaclein as a marker allergen related to systemic reactions in peach allergy. Ann Allergy Asthma Immunol. 2014;112(2):175-177.e3. doi:10.1016/j.anai.2013.11.003.Klingebiel C, Chantran Y, Arif-Lusson R, et al. Pru p 7 sensitization is a predominant cause of severe, cypress pollen-associated peach allergy. Clin Exp Allergy. 2019;49(4):526-536. doi:10.1111/cea.13345Fernández-Rivas M, Gómez García I, Gonzalo-Fernández A, et al. Development and validation of the food allergy severity score. Allergy. 2022 May;77(5):1545-1558. doi: 10.1111/all.15165. Epub 2021 Nov 12. PMID: 34716996; PMCID: PMC9298738Takei M, Nin C, Iizuka T, et al. Capsicum Allergy: Involvement of Cap a 7, a New Clinically Relevant Gibberellin-Regulated Protein Cross-Reactive With Cry j 7, the Gibberellin-Regulated Protein From Japanese Cedar Pollen. Allergy Asthma Immunol Res. 2022;14(3):328-338. doi:10.4168/aair.2022.14.3.328FIGURESTable 1 . Demographic and clinical characteristics of patients according to their sensitization to Pru p 3 and Pru p 7.