IL4 and chlamydia trachomatis infectious disease: To explore the ability of C. pneumoniae to survive in polarized human macrophages and to assess the influence of macrophage polarization on the control of chlamydial infection, we pre-differentiated human monocytes with GM-CSF and M-CSF for 7 days, followed by treatment of the resulting M1-like and M2-like macrophages with IFN-γ/LPS or IL-4 for 48 h to yield M1 and M2 macrophages.