Lung-Residing Myeloid-derived Suppressors Display Dual Functionality in Murine Pulmonary Tuberculosis

Rationale: Myeloid cells encompass distinct populations with unique functions during homeostasis and disease. Recently, a novel subset of innate cells, myeloid-derived suppressor cells (MDSCs), has been described in cancer, which suppresses T-cell responses and fosters disease progression. The role of MDSCs in infection is insufficiently addressed.Objectives: To examine the presence and function of MDSCs during experimental pulmonary tuberculosis (TB) and further understand the immunologic consequences of direct interactions between MDSCs and lung bacterial pathogens.Methods: Using cell-based approaches and experimental mouse models for pulmonary TB we characterized MDSCs as novel myeloid populations directly interacting with Mycobacterium tuberculosis (Mtb).Measurements and Main Results: MDSCs readily phagocytosed Mtb, and released proinflammatory (IL-6, IL-1α) and immunomodulatory (IL-10) cytokines while retaining their suppressive capacity. MDSCs were identified at the site of infection in the lung in ...