Macrophages maintain splenic HSCs. (A) Gating for splenic macrophages (top). Plots for macrophages in respective groups (bottom; n = 3–10). (B) Histogram for CD169 expression on splenic macrophages. (C) Macrophage depletion in CD169 iDTR mice. Plots show depletion of splenic macrophages after diphtheria toxin (DT) treatment. LSKs, HSCs, and GMPs in the spleen (D) and bone marrow (E) of CD169 iDTR mice after depletion (n = 5–10). (F) LSKs, HSCs, and GMPs in the blood of PBS and DT-treated mice (n = 5–9). Data were pooled from 2–4 independent experiments and are shown as mean ± SEM. Significance was determined by Mann-Whitney test. *, P < 0.05; **, P < 0.01; ***, P < 0.001.