IL-4 treatment can cure established gastrointestinal nematode infections in immunocompetent and immunodeficient mice.

We examined the ability of a long acting formulation of IL-4 (IL-4/anti-IL-4 mAb complexes) to limit established infections of normal and immune deficient mice with two nematode parasites: Heligmosomoides polygyrus and Nippostrongylus brasiliensis. IL-4, at a dose of 5 to 20 micrograms every 3 to 4 days, rapidly decreased egg production and, over a period of 6 to 9 days, terminated infection in H. polygyrus-inoculated BALB/c mice. IL-4 treatment also considerably decreased egg production in H. polygyrus-inoculated CB.17 severe combined immunodeficient (SCID) mice and terminated infection in N. brasiliensis-inoculated SCID mice and anti-CD4 mAb-treated BALB/c mice. IL-4 was less effective at limiting H. polygyrus infection if administrated when parasites were in larval stages than if administered after adult worms had developed. The effects of IL-4 were inhibited completely by an mAb that specifically blocks the mouse IL-4R. These observations demonstrate that IL-4 can limit the fecundity and survival of gastrointestinal nematode parasites through effects on the host that are independent of the specific immune system.