Cellular responses to sterile injury in MerTK^−/− mice.

<p>Control or MerTK^−/− mice received sponges for 14 days. (A) Flow cytometry analysis was used to determine the proportion of F4/80⁺ macrophages and Ly6G⁺ neutrophils in the day 14 wounds of control and MerTK^−/− mice. (B) The F4/80⁺ macrophage population was assessed for the frequency of Ly6C^hi and Ly6C^low subsets. (C) The expression of activated caspase-3/7 was determined by FACS in control (blue histogram) and MerTK^−/− (red histogram) mice at 14 days after wounding. The negative control is shown as a grey histogram. As an indication of neutrophil phagocytosis by wound monocytes/macrophages (Mo/Mφ), the frequency (D) and number (E) of Ly6C^hi and Ly6C^low cells expressing intracellular Ly6G was determined by FACS. Representative dot plots showing intracellular Ly6G expression in Ly6C^hi and Ly6C^low wound monocytes/macrophages are shown in (D). Plots were gated on F4/80⁺ cells. Proportion of Ly6C^hiLy6G⁺ and Ly6C^lowLy6G⁺ cells (±SD) is indicated in quadrants. Data shown in (D) are representative of 6 mice. Data shown in A–D are the mean ± SD, n = 6 mice per group. * p<0.05.