Clinical features and allergen analysis in five children with macadamia nut allergy

Abstract

Few cases of macadamia nut allergy have been documented, and the major allergens have not been fully analyzed. We summarized the clinical features of five children with macadamia nut allergy and investigated the allergens in macadamia nut. We enrolled five patients (three girls and two boys) with the diagnosis of macadamia nut allergy at Tokyo Metropolitan Children’s Medical Center. The serum-specific IgE level against macadamia nut was assessed, and a skin prick test was done. We determined the molecular weight of macadamia nut allergens by SDS-PAGE and IgE-immunoblotting. Our study was approved by the independent review board of the Tokyo Metropolitan Children’s Medical Center, and we obtained informed consent from the patients’ parents. The age of onset of macadamia nut allergy ranged from 2 to 3 years. All the 5 children had oropharyngeal symptoms and facial urticaria and/or edema, and anaphylaxis was observed in two children. Three children had atopic eczema and three children had other food allergies. Four of five children had positive results for macadamia nut-specific IgE (range: 0.58 to 28.4 UA/ml), and the results of a skin prick test for macadamia nut were positive in all five children. IgE-immunoblotting showed two predominant bands at approximately 15 and 20 kDa in all five children and two individual bands at approximately 40 and 50 kDa in two children with anaphylaxis. Macadamia nut may induce severe allergic reactions in children. Understanding IgE-binding proteins might be useful for detecting severe cases in macadamia nut allergy.