Clinical and serological characterization of the α-Gal syndrome - importance of atopy for symptom severity in a European cohort

Abstract: Background The α-Gal syndrome (AGS) is a novel form of food allergy. Patients experience delayed severe allergic reactions after mammalian meat consumption due to IgE antibodies directed against the carbohydrate galactose-α1,3-galactose (α-Gal) present in mammalian meat. The onset of the disease is associated with tick bites. Objective To characterize a cohort of AGS patients from Sweden on a clinical and serological level, and identify risk factors for disease severity. Methods A total of 128 patients with symptoms after mammalian meat intake and IgE to α-Gal were included. Medical examination and diagnosis were made by an allergologist and questionnaires were filled in regarding onset of symptoms, tick exposure, and airborne allergies. Serum IgE reactivity against multiple food and airborne allergens, as well as protein extract from the tick Ixodes ricinus was measured using ImmunoCAP. Results The majority of patients were middle-aged, with equal gender distribution. Nearly all reported symptoms more than 2 hours after meat consumption. Urticaria (90%) and gastrointestinal symptoms (74%) were most common. Almost half of the patients suffered from anaphylaxis, and α-Gal IgE levels were significantly higher among these patients compared to those without anaphylaxis. Nearly all patients had been tick bitten and 75% had IgE against Ixodes ricinus. More than half of the AGS patients were atopic and atopy increased the risk of anaphylaxis with pulmonary manifestations. Only 2 patients belonged to blood group B. Conclusion AGS is an upcoming food allergy where patients report severe symptoms and tick bites. Atopy was found to affect the manifestation of the disease in Swedish patients.