Macrophage Polarization.

<p><b>(A)</b> CD14 positive human blood monocytes were treated either with 25 ng/mL GM-CSF or 50 ng/mL M-CSF for 7 days to yield M1-like or M2-like macrophages. M1-like macrophages were activated with GM-CSF, LPS and 50 ng/mL IFN-γ for an additional 48 h to yield M1 macrophages, while M2-like macrophages were treated with M-CSF and IL-4 to yield M2. <b>(B)</b> To examine the impact of macrophage polarization on survival and proliferation of <i>C</i>. <i>pneumoniae</i>, M1 and M2 macrophages were infected and cultured with <i>C</i>. <i>pneumoniae</i> for 24 h. <b>(C)</b> M1-like macrophages were infected with <i>C</i>. <i>pneumoniae</i> and cultured for 48 h in the presence of GM-CSF and IFN-γ, while infected M2-like macrophages were cultured with M-CSF and IL-4. Uninfected macrophages served as control.