Myeloid-derived suppressor cells (MDSC) encompass a subset of myeloid cells, which suppress both innate and adaptive immune functions. Since Mycobacterium tuberculosis (M. tuberculosis) can infect these cells, interest has emerged to study the antimicrobial response of MDSC to mycobacteria causing tuberculosis. Reactive oxygen species (ROS) are critical mediators to control intracellular replication of M. tuberculosis and MDSC express high levels of these effector molecules. Here we describe the flow cytometric assessment of total cellular ROS produced by MDSC in response to infection with M. tuberculosis and compare it with the ROS activity of non-MDSC myeloid cells. To further understand the dynamics of host-pathogen interactions, we provide details on methods for measurement of the intracellular replication of M. tuberculosis within MDSC. Of note, these procedures were adopted for primary MDSC and non-MDSC subsets isolated from human immunodeficiency virus (HIV)-uninfected or HIV-infected individuals, in vitro infected with M. tuberculosis to mimic M. tuberculosis mono- or HIV-M. tuberculosis coinfection, respectively.
Keywords: Antimicrobial activity; Cell ROS; Flow cytometry; HIV-M. tuberculosis coinfection; MDSC sorting; Mitochondrial ROS; Monocytic MDSC.