Age and Geographical Location Determine the Molecular Pattern of Walnut Allergy in Madrid, Spain

Study design, setting, and subjectsIn a transversal single-center cohort study, a total of 51 patients with walnut allergy from Fundación Jiménez Díaz Hospital (Madrid, Spain) were recruited.All walnut allergic patients included in the study were diagnosed during the years 2020-2021 and met the criteria of the SEAIC Subcommittee on Adverse Food Reactions [1].Walnut allergy was diagnosed in patients having a clear history of adverse reactions due to walnut suggestive of IgE-mediated allergy, showing positive skin prick-by-prick tests, or by positive sIgE and/or food challenge tests to walnut.The exclusion criteria were those set out in the EAACI document on standardization of food challenge tests [2].A serum sample was obtained from each patient and stored at -80º C until use.The Fundación Jiménez Díaz Ethic Committee approved this study and written informed consent was obtained from all subjects. sIgE testingAllergen-sIgE to nuts was measured by ImmunoCAP (ThermoFisher Scientific AB, Uppsala, Sweden) following the manufacturer's recommendations.Besides, the multiplex test system ALEX 2 (MacroArray Diagnostics GmbH, Wien, Austria) was performed according to the manufacturer's instructions.sIgE levels were expressed in kU/L and kUA/L, and sIgE values ≥0.35 kU/L and ≥0.30 kUA/L were considered positive, respectively.