In Vitro Polarization of Murine Macrophage Macrophages are tissue-resident professional phagocytes, which play an important role in immune-regulation. Activated macrophages are routinely classified into two different types: M1-macrophages (classic activation) and M2- macrophages (alternative activation), which perform pro- and anti-inflammatory active respectively. In vitro polarization of macrophages is achieved by stimulation in the presence of appropriate activation factors. Here we describe a comprehensive protocol to obtain specific macrophage subtypes through in vitro polarization from murine bone marrow derived and peritoneal macrophages. Reagents Stimulating factors: Murine macrophage colony-stimulating factor (M-CSF or CSF-1), IL-4, IL-10, IFN-γ, LPS. DMEM+: 10 % FBS, 2 % sterile-filtered penicillin/streptomycin (10 mg/mL) in high-glucose DMEM medium. ACK buffer: 150 mM NH4Cl, 10 mM KHCO3 and 500 μM EDTA, sterile-filtered. Sterile PBS Trypsin–EDTA (0.25 % in PBS). 70 % ethanol https://www.creative-diagnostics.com/in-vitro-polarization-of-murine-macrophage.h tm