Although IgG subtypes have been shown to contribute to anaphylaxis in animals passively immunized and intravenously challenged mice (44–46), IgG has also been shown to play a protective role against IgE-mediated severe food allergy reactions, either by competing with IgE for the allergen or binding to FcγRIIb on granulocytes to hinder IgE binding to FcεRI (47, 48). This evidence concerns the gene IGHE and allergic disease.