Next, we sought to determine whether alveolar macrophages expressed Arg1 but not NOS2 upon infection by A. fumigatus. Mice were infected with 10×106 RC and CD11c+ cells were recovered by BAL 48 hours p.i. In addition to the increase in the number of CD11c+ cells in the alveolar space after fungal infection, the alveolar macrophages in the infected mice also acquired a distinct morphology and were found to be more vacuolated as compared to those in naïve mice (Figure 3A). Here, NOS2 is linked to infection.