RESUMO
Myeloid-derived suppressor cells (MDSCs) represent a subset of myeloid cells that expand under pathological conditions, such as cancer development, acute and chronic infections, trauma, bone marrow transplantations, and some autoimmune diseases. MDSCs mediate a negative regulation of the immune response by affecting different T lymphocyte subsets. Potential mechanisms, which underlie this inhibitory activity range from those requiring direct cell-to-cell contact with others, more indirect, and mediated by the modification of the microenvironment. Pharmacological inhibition of MDSC suppressive pathways is a promising strategy to overcome disease-induced immune defects, which might be a key step in enhancing the effectiveness of immune-based therapies.