IFN INHIBITS INFLAMMATORY RESPONSES AND PROTECTIVE IMMUNITY IN MICE INFECTED WITH THE NEMATODE PARASITE, NIPPOSTRONGYLUS-BRASILIENSIS

Mice infected with the gastrointestinal nematode parasite Nippostrongy lus brasiliensis (Nb) develop responses associated with enhanced produ ction of IL-4 (increased serum IgE levels and intestinal mucosal masto cytosis) and IL-5 (tissue and peripheral blood eosinophilia). The anta gonistic effects of IFN on IL-4-mediated responses prompted an examina tion of the effects of IFN on the host response to Nb. Treatment with rIFN-alpha and rIFN-gamma induced a marked increase in parasite egg pr oduction (fecundity) in BALB/c mice infected with Nb and delayed intes tinal expulsion of adult worms. Treatment with rIFN-alpha or rIFN-gamm a also inhibited the rise in peripheral blood eosinophilia that follow s inoculation with Nb, and the intensity of pulmonary perivascular tis sue eosinophilia. However, Nb-induced increases in serum IgE levels an d intestinal mastocytosis were only temporarily delayed by IFN. Induct ion of endogenous IFN production by injection of fixed Brucella abortu s into mice infected with Nb also resulted in an increased worm fecund ity and delayed adult worm expulsion. These effects were ablated when mice given Brucella abortus also received injections of neutralizing a nti-IFN antibodies. Thus, IFN inhibit host protective immunity to Nb, perhaps by interfering with the production and effects of Th2 cytokine s.