Assessment of Parasite–Microglia Interactions In Vitro

: An extensive number of parasites are able to invade the central nervous system (CNS) and cause a plethora of pathologies. Microglia, the resident macrophages of nervous tissue, are responsible for the protection against intruders, and therefore, they are an important line of defense against parasites. The phagocytosis is one of the weapons in the microglia's arsenal to fight against parasites. Several prior studies of microglia-parasite interactions and phagocytosis have been performed using microscopic techniques. As this methodology allows only a limited number of cells to be analyzed, additional approaches are required to provide a more complete picture of how microglia interact with these pathogens. Here, we describe a protocol based on flow cytometry to analyze single-celled parasites/microglia interactions in thousands of events in an accurate and reliable way. We use Trypanosoma brucei as a model organism, as it is a well-known parasite causing primary meningoencephalitis. However, the interaction/phagocytosis assay can be applied to other single-celled parasites as well.