IGHE and Allergy: 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).