Tissue macrophage content in wild-type and macFoxp1tg mice was assessed using immunostaining and 4-color flow cytometry. Photomicrographs of lung (original magnification 40×/0.65), liver (×40), and spleen (10×/0.25) stained with the macrophage-specific antibodies F4/80 (A) and Mac-3 (B). (C) Four-color flow cytometry was performed to evaluate leukocyte subpopulations within the spleen. Splenic monocytes/macrophages (CD11b^hiCD90^midB220^midCD49b^midNK1.1^midLy6G^mid cells) were divided into F4/80^hi CD11c^hiI-A^bhi macrophages/dendritic cells and F4/80^lo CD11c^loI-A^b1o monocytes. Representative flow cytometry and percentage gate quantification of F4/80^hi CD11c^hiI-A^bhi macrophage/dendritic cells (mean ± SD; n = 3 spleens per genotype).