In vitro flow cytometry assay to assess primary human and mouse macrophage phagocytosis of live cells.

Although tumor-associated macrophages are generally immunosuppressive, macrophages may also promote tumor clearance via phagocytosis of live tumor cells. Here, we present a protocol for assessing macrophage engulfment of tumor cells in vitro using flow cytometry. We describe steps for cell preparation, reseeding macrophages, and setting up phagocytosis. We then detail procedures for collecting samples, staining macrophages, and flow cytometry. The protocol is applicable to both mouse bone-marrow-derived macrophages and human monocyte-derived macrophages. For complete details on the use and execution of this protocol, please refer to Roehle et al. (2021)..