FIG. 4.

NO production by spleen cells from infected WT, IL-4^−/−, IL-12^−/−, and IL-4/IL-12^−/− mice. In vitro nitrite levels in supernatants of spleen cell cultures from mice exposed to ∼70 cercariae 47 days earlier were measured following stimulation with SEA. IL-4^−/− and IL-4/IL-12^−/− mice had significantly higher (∗, P < 0.05) NO levels than did WT and IL-12^−/− mice. There were five mice per group. Data are means ± standard errors of the means and are representative of three separate experiments.