In Vitro Phagocytosis Assays

We have used an in vitro phagocytosis assay called the monocyte monolayer assay (MMA) for over 40 years to assess the potential clinical significance of antibodies to red blood cells. This assay uses human monocytes, not macrophages, but has been a reliable predictor of hemolysis outcomes in the face of auto- or alloantibodies. However, this assay can be slightly modified to be used with phagocytic cells other than monocytes and with different animals' phagocytes. Indeed, we have been working on using human macrophages in this assay as well as mouse monocyte-macrophages. Thus, we now use the acronym MOMA to mean MOnocyte-Macrophage Assay. Herein, we present detailed methods for performing in vitro phagocytosis assays that use human monocytes, cultured macrophages (MOMA), M1 or M2 macrophages, mouse PBMCs, or the mouse macrophage cell line, RAW 264.7.