• Jörg Fischer, Hoai-Nam Huynh, Johanna Hebsaker, Stephan Forchhammer, and Amir Sadegh Yazdi.
• Department of Dermatology, Faculty of Medicine, Eberhard Karls University Tübingen, Tübingen, Germany, joerg.fischer@med.uni-tuebingen.de.
• Int. Arch. Allergy Immunol. 2020 Jan 1; 181 (2): 119-127.

BackgroundAlpha-gal syndrome is a complex allergy with high clinical relevance regarding mammalian-derived food and drugs and is characterized by the presence of IgE antibodies directed at the carbohydrate galactose-α-1,3-galactose. As not all alpha-gal sIgE-positive individuals pre-sent clinical symptoms upon consumption of mammalian meat, the diagnostic value of alpha-gal sIgE has yet to be clarified.ObjectiveTo investigate the prevalence of alpha-gal-sIgE positivity among allergy patients, examine the impact of tick bites as associated risk factors and determine the diagnostic value of alpha-gal-sIgE positivity.MethodsA retrospective cross-sectional study evaluating patients in the Allergy Unit was performed. Alpha-gal-sIgE levels were assessed by ImmunoCAP assay. Exposure to tick bites was assessed by a questionnaire. A receiver operating characteristics (ROC) curve analysis was performed to determine the diagnostic value of alpha-gal sIgE for the diagnosis of alpha-gal syndrome.ResultsIn the study population (n = 1369), the overall prevalence of alpha-gal-sIgE-positive (≥0.10 kUA/L) individuals was 19.9%, and the highest prevalence (30.2%) was found in patients with insect venom allergies. A reported tick bite within the 12 months prior to blood sampling significantly increased the risk of alpha-gal-sIgE positivity (OR 2.084). The ROC curve analysis indicated alpha-gal sIgE ≥0.54 kUA/L as the optimal cutoff point for assessing the diagnostic value of alpha-gal syndrome in allergy patients.ConclusionsIn allergy care settings, alpha-gal-sIgE positivity is a common finding. Alpha-gal sIgE is a sensitive marker in the diagnosis of alpha-gal syndrome but has limited predictive value for the characteristics or severity of this allergy.© 2019 S. Karger AG, Basel.

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