In Vitro Methods to Evaluate Macrophage Polarization and Function in Cancer

Tumor-associated macrophages (TAMs) play a key immunosuppressive role that limits the ability of the immune system to fight cancer and hinder the anti-tumoral efficacy of most treatments currently applied in the clinic. However, a key feature of macrophages is their phenotypical and functional plasticity, which called their attention as promising targets for therapeutic intervention based on their elimination or reprogramming toward M1-like cytotoxic effector cells, with anti-tumor functions. This polarization status of macrophages can be studied in terms of molecular markers and functional activities, using an appropriate combination of experimental methodologies, both in vitro and in vivo. Here we focus on describing in vitro protocols to isolate primary monocytes from buffy coats and to study macrophage phenotype and function, after exposure to new therapies, by a combination of flow cytometry, RT-PCR, and ELISA analysis. We also provide the methodology to evaluate in vitro the cytotoxic activity of treated macrophages toward cancer cells.