Figure 5.

IL-10 induces phagocytosis by macrophages and clodronate depletion of phagocytes from mdx mice selectively reduces M2c macrophages in skeletal muscle. (A–D) Flow cytometric data showing that IL-10 stimulation of macrophages increases macrophage phagocytosis. Macrophages were untreated with exogenous cytokines (A), treated with IFN-γ (B), IL-4 (C) or IL-10 (D) prior to incubation with flourescent microspheres for phagocytosis. Cells were then analyzed by flow cytometry to determine the proportion of cells that contained fluorescent microspheres, as an index of phagocytosis. Neither IFN-γ (68.1%) or IL-4 (61.2%) increased the proportion of cells that were phagocytic, compared with untreated controls (69.4%). However, IL-10 treatments increased the proportion of cells that were phagocytic (79.5%). (E and F) Intraperitoneal injections of clodronate-containing liposomes significantly reduced the numbers of macrophages (E) and MHC-2-presenting cells in the quadriceps muscles of 4-week-old mdx mice. Each experimental group included muscles from six mice. Asterisks indicate a significant difference from PBS-treated controls. Bars represent sem. (G–J) Quantitative, real-time PCR data show that clodronate-mediated depletions of phagocytes did not cause a significant change in the expression of CD68 in the quadriceps muscles of 4-week-old mdx mice (G), but caused large, significant reductions in the expression of CD206 (H), CD163 (I) and IL-10 (J). Each experimental group included muscles from five mice. Asterisks indicate a significant difference from PBS-treated controls. ‘n.s.' indicates no significant effect of the clodronate treatment. Bars represent sem, which is too small to appear for graphs of some data sets.