Figure 2. iNOS activity controls the influx of activated mononuclear phagocytes and T cells to the lungs.

Flow cytometry characterization of lung infiltrating leucocytes (LIL) from iNOS^−/− and WT mice after i.t. infection with 1×10⁶ P. brasiliensis yeast cells. Lungs of iNOS^−/− and WT mice (n = 6–8) were excised, washed in PBS, minced, and digested enzymatically. At weeks 2 (A, C) and 10 (B, D) after infection, lung cell suspensions were obtained and stained as described in Materials and Methods. (A, B) Phenotypic characterization of CD11b⁺ mononuclear phagocytes expressing CD80, CD86 and CD40 and dendritic cells expressing high levels of CD11c and CD86 (CD11c^highCD86^high). An increased presence of mononuclear phagocytes was observed in deficient mice, while the number of dendritic cells was equivalent in the lungs of both mouse strains. (C, D) Characterization of T cell subsets by flow cytometry in LIL obtained at weeks 2 (C) and 10 (D) after infection. To characterize the expansion of regulatory T cells in LIL, surface staining of CD25⁺ and intracellular FoxP3 expression were back-gated on the CD4⁺ T cell population. The acquisition and analysis gates were restricted to macrophages (A, B) or lymphocytes (C, D). The data represent the mean ± SEM of the results from 6–8 mice per group and are representative of two independent experiments. * (P<0.05), ** (P<0.01) and *** (P<0.001), compared with WT mice.