The identification of inflammatory monocytes during L. major infection. (A) Fluorescent microscopy of PBMC from uninfected CX3CR1^GFP/+ RAG2^−/− transgenic mice showing GFP^High (GR1⁻) and GFP^Low (GR1⁺) cells. (B) Flow cytometry analysis of blood monocytes (PBMC) from CX3CR1^GFP/+ mice showing that GR1⁺ monocytes (top right histogram) are derived from the GFP ^low population of blood monocytes, whereas GR1⁻ monocytes (bottom right histogram) are derived from the GFP^High population of monocytes. (C) Flow cytometry analyses of cells from the footpads of CX3CR1^GFP/+ mice before (top) and 24 h after (bottom) infection with 2 × 10⁶ L. major. Cells were gated based on FSC x SSC profile eliminating dead cells and debris, using the F4/80⁺ antibody. The numbers represent the frequency of gated cells. This plot is representative of at least three experiments using five mice per group. (D) The frequency of GR1⁺ monocytes in infected footpads at the designated times after infection. The numbers represent the mean of the frequency of gated cells taken from three experiments using three mice per group. Bar, 50 μm.