Effects of inflammation on recruitment of monocytes to colon. Monocyte recruitment into inflamed colon was studied by transferring 2 × 106 fluorescence-activated cell sorted Ly6Chi bone marrow monocytes from CD45.1+/CD45.2+ CX3CR1+/gfp mice into CD45.1+ wild-type (WT) mice on d3 of dextran sodium sulfate (DSS) colitis. After a further 2 days of DSS, mice were returned to normal drinking water. (a) Donor-derived cells within the live-gated CD45+ CD11b+ fraction of colonic LP cells of colitic mice 24 and 96 h after transfer compared with PBS-injected controls. CX3CR1int and CX3CR1hi gates were set using donor-derived monocytes in blood, which remain CX3CR1int. (b) Expression of F4/80 and CD11c by donor-derived cells in inflamed colon 24 and 96 h after transfer, compared with endogenous CD45+ CD11b+SSClo cells in colon on d4 DSS. (c) Expression of Ly6C and MHCII by F4/80+ donor-derived cells in inflamed colon 24 and 96 h after transfer, compared with endogenous CD45+ CD11b+ F4/80+ SSClo cells in colon on d4 DSS. (d) Mean fluorescence intensity (MFI) of CX3CR1-green fluorescent protein (GFP) expression on donor-derived monocytes derived from the colon and blood of resting CCR2−/− mice or from WT mice taken on day 4 of DSS colitis, with two mice per group. Results are representative of two individual experiments. PBS, phosphate-buffered saline.