Th1 cells protect against intracellular pathogens, activate phagocytes, induce IgG2a antibodies, and promote delayed-type hypersensitivity responses, whereas Th2 cells protect against extracellular pathogens, activate eosinophils, induce IgE-mediated allergic reactions, and promote other humoral responses in which IgG1 predominates [10]. Here, IGHE is linked to allergic disease.