FIG. 2.

IDO-specific inhibitor 1-MT antagonizes IFN-γ-induced inhibition of N. caninum growth. HFFs (3 × 10⁴ cells per well) were stimulated with IFN-γ (250 U/ml) in the presence or absence of 1-MT (1.5 mM). (A) After 72 h of stimulation supernatants were harvested, and the kynurenine content was determined by use of the Ehrlich reagent. The data are means and standard errors of the means of four independent experiments performed in triplicate. Significant inhibition of IDO by 1-MT is indicated by an asterisk. OD₍₄₉₂₎, optical density at 492 nm. (B) After 72 h cultures were infected with N. caninum tachyzoites (2 × 10⁴ tachyzoites per well). N. caninum growth was monitored using [³H]uracil, and the data are means and standard errors of the means of four independent experiments performed in triplicate. A significant inhibitory effect of 1-MT (P < 0.05) is indicated by an asterisk.