IL4 and allergic disease: Our confirmation of the critical function of the IgG:IgE ratio in allergy is consistent with clinical investigation of an antibody blocking the IL-4/IL-13 pathway (Dupixent, anti-IL-4Rα, dupilumab), which reduces IgE and has shown impressive efficacy in multiple allergy-related conditions such as asthma49, atopic dermatitis50–52, and nasal polyposis53; blocking this pathway could provide a longer-term approach to the treatment of allergy.