FIG. 4.

Effect of SNP or IFN-γ on established infection of BMMΦ. At 4 days after C. burnetii infection, cultures were treated with SNP or IFN-γ. After 24 or 48 h, supernatants were removed for nitrite determination, and cells were processed as described in Materials and Methods. (A) Percentage of cells with LRVs and nitrite in culturesupernatants as a function of SNP concentration or IFN-γ treatment for 48 h. (B) Relative bacterial loads in LRVs of macrophages treated with SNP or IFN-γ for 24 (gray bars) or 48 h (black bars). (C) Vacuolar central optical section areas in cells treated with 100 μM SNP (▵), 50 ng of IFN-γ/ml (○), or controls (•) as a function of time. Results are expressed as the means ± standard deviations of one of two experiments. Significant differences between untreated control and treated cultures are indicated (✽, P < 0.05; ✽✽, P < 0.01)