Studies of the inverse association between parasitic infections and allergy indicated that parasitic infections may “protect” allergy by inducing suppressive cytokines released from regulatory lymphocytes, ablating the eosinophil response, making effector T helper 2 (Th2) cells enter anergic state and switching antibody production from IgE to the non-inflammatory isotype IgG4 (142, 143). This evidence concerns the gene IGHE and allergic disease.