Analysis of PD-L2 expression on macrophages in vivo during N brasiliensis infection. Lung (A) and BAL (B) from wild-type (WT) and Stat6^−/− mice were analyzed before or at indicated time points after N brasiliensis infection for PD-L2 expression by flow cytometry. Dot plots show staining of F4/80 and PD-L2 or isotype control on CD11c⁺ autofluorescence^hi-gated cells at day 13 after N brasiliensis infection. Graphs show the frequency and absolute number of PD-L2⁺ macrophages in WT (filled circles) and Stat6^−/− (open circles) mice as mean ± SE with 3 individual mice from 2 independent experiments. (C) Detection of Ym1 (blue) and PD-L2 (red) expression in alveolar macrophages (arrows) in the lung of WT but not Stat6^−/− mice that had been infected with N brasiliensis 13 days before. Original magnification of the objective was ×40. (D) T-cell–derived IL-4/IL-13 is required for PD-L2 expression on AAM in vivo. Analysis of PD-L2 expression on macrophages in BAL and lung (F4/80⁺ CD11c⁺ autofluorescence^hi) in complete IL-4/IL-13–deficient mice (IL-4/IL-13^−/−), mice deficient of IL-4/IL-13 only in T cells (CD4Cre/IL-4/IL-13^F/F), and control mice (IL-4/IL-13^F/F) 13 days after N brasiliensis infection. Bars show the frequency of PD-L2⁺ macrophages as means of 2 mice (dots).