FIG. 6.

Effect of IFN-γ or IFN-γ-LPS on the expression of iNOS and IDO (A and C) and on the growth of C. trachomatis L2 and C. muridarum MoPn (B) in RAW 264.7 macrophages. RAW 264.7 macrophages were uninfected or infected with chlamydiae and then incubated in the complete culture medium described in Table 1 plus IFN-γ (20 U/ml) or IFN-γ (20 U/ml)-LPS (20 ng/ml) with or without NMMA (1 mM). Cultures were harvested and processed for the various assays 24 h later as described in the legend to Fig. 1. Growth data are presented as IFU (log₁₀) and represent the means ± standard errors of triplicate determinations. *, P < 0.0001 compared to the untreated control culture. Medium nitrite levels were determined after 48 h of incubation using the Griess reagent. Data are presented as μM nitrite and represent the means of two independent experiments with ranges shown.