Helminth infections are potent Th2 response inducers in both humans and experimental models, characterized by eosinophilia, high titers of circulating IgE, enhanced Th2 cytokine profile [e.g., increased secretion of interleukin 4 (IL-4) and IL-5], and regulatory (IL-10, TGF-β) cytokines and reduced Th1 type cytokines [e.g., interferon (IFN)-γ] [3]. The gene discussed is IL4; the disease is helminthiasis.