Monocytes contribute to four cMΦ subpopulations in adult mice. (A) WT mice were lethally irradiated and reconstituted with BM from Ubow:CX3CR1^GFP/+ mice. cMΦ were analyzed for contribution of dTomato⁺ cells at indicated time points after reconstitution and graft-derived cells were analyzed for CX3CR1 and MHCII expression. Data are presented as mean percentage ± SEM (n = 3–7) and derived from two independent experiments. (B) Mixed BM chimeras were generated by reconstituting lethally irradiated WT mice (CD45.1/CD45.2) with BM from CCR2^−/−:CX3CR1^GFP/+ (CD45.2) and WT CX3CR1^GFP/+ (CD45.1) mice. cMΦ, circulating CD11b⁺CD115⁺ monocytes (Ly6C⁺ and Ly6C⁻) and B220⁺ B cells were analyzed for WT (CD45.1) and CCR2^−/− (CD45.2) contribution. Host- and graft-derived cMΦ were analyzed for the ratio of MHCII⁺/MHCII⁻ cMΦ. Bars show median (n = 4). *, P ≤ 0.05, Mann-Whitney test. (C) Parabiosis was established between adult CCR2^−/− (CD45.2) and WT (CD45.1) mice. After 10 wk, CCR2^−/− mice were analyzed for contribution of CD45.1⁺ non-host cells to cMΦ (total, MHCII⁺, and MHCII⁻), circulating monocytes (Ly6C⁺ and Ly6C⁻), and B cells. For CD45.1⁻ host and CD45.1⁺ non-host cMΦ, the ratio of MHCII⁺/MHCII⁻ cMΦ was calculated and compared. Bars show median (n = 4). **, P ≤ 0.01, Mann-Whitney test. (D) BM chimeras were generated by transfer of LT-HSC isolated from panYFP mice into nonirradiated Rag2^−/−γ_c^−/−Kit^W/Wv mice. cMΦ (total, MHCII⁺, and MHCII⁻) and neutrophils (Gr1^hi and SSC^hi) were analyzed for contribution of grafted YFP⁺ cells 8 wk after transplantation. Bars show median (n = 6). **, P ≤ 0.01, Mann-Whitney test. Data in all panels are representative of two independent experiments.