In a nonfood allergy model in which OVA-specific IgE is induced by injecting 2 doses of OVA plus Alum i.p., we also observed that OVA-specific IgE, but not IgG1, was severely impaired in Il4+/– mice (Supplemental Figure 5E), a result consistent with previously published observations (10). Here, IGHE is linked to allergic disease.