Flow cytometric quantification of CD45+/CXCR4+/ColI+ fibrocytes in mouse lung tissue. Total lung cells were isolated from mice (three to six mice in each category) ten days after saline or bleomycin treatment. The mice had been treated daily with CSD or control peptide starting one day prior to saline or bleomycin treatment. CD45+/CXCR4high/ColI+ fibrocytes were quantified by performing flow cytometry. (A) Results from a typical experiment in which lung cells from the indicated individual mice were gated based on CD45 staining, then resolved on two-dimensional scatterplots based on their ColI and CXCR4 staining. Vertical and horizontal bars delimit the zone in which cells stained with isotype controls are found. We refer to the cells that are slightly into the upper right quadrant as CXCR4low, and we refer to cells within the box as CXCR4high. Therefore, the square box contains cells that are CD45+/CXCR4high/ColI+. (B) The percentage of cells falling within the square box is presented for each category of mice. The data represent the average of from three to six mice in each category ± standard error of the mean. **P < 0.01. *P < 0.05.