IL-13, IL-4Rα, and Stat6 are required for the expulsion of the gastrointestinal nematode parasite Nippostrongylus brasiliensis

Although IL-4 induces expulsion of the gastrointestinal nematode parasite, Nippostrongylus brasiliensis, from immunodeficient mice, this parasite is expelled normally by IL-4-deficient mice. This apparent paradox is explained by observations that IL-4 receptor alpha chain (IL-4R alpha)-deficient mice and Stat6-deficient mice fail to expel N. brasiliensis, and a specific antagonist for IL-13, another activator of Stat6 through IL-4R alpha, prevents worm expulsion. Thus, N. brasiliensis expulsion requires signaling via IL-4R alpha and State, and IL-13 may be more important than IL-4 as an inducer of the State signaling that leads to worm expulsion. Additional observations made in the course of these experiments demonstrate that State signaling is not required for IL-4 enhancement of IgG1 production and actually inhibits IL-4-induction of mucosal mastocytosis.