Tissue macrophages turnover at steady state. Healthy, unmanipulated RMs were infused with BrdU intravenously for 5 days. Five days from the conclusion of administration (day 10) and 14 days later (day 24), blood and tissue cells were analyzed by flow cytometry to assess BrdU incorporation. (A) Representative plots showing percent BrdU⁺ cells of at least 1000 cells defined as single, live, CD45⁺, CD11b⁺, HLA-DR⁺, CD20⁻ mononuclear cells from the same animal at each time point. (B) BrdU levels from all 4 healthy unmanipulated animals in tissue macrophages. ∗∗∗P < .001, using Wilcoxon matched-pairs test.