title: Tolerance and immune suppression in the tumor microenvironment.
abstract: The concept of immunological tolerance has guided and permeated much of modern immunology. Ray Owen's ground-breaking observations in twin cattle provided the first mechanistic explanation for tolerance to self-molecules and established tolerance as a beneficial process that protects the host against autoreactivity. However, his studies also opened the door to understanding that tolerance may be detrimental, such as occurs when cancer cells induce tolerance/immune suppression resulting in inhibition of anti-tumor immunity. This article briefly traces the early history of the field of tumor immunology with respect to tolerance, and then focuses on a relatively recently identified population of cells called myeloid-derived suppressor cells (MDSCs). MDSC are instrumental in causing tolerance/immune suppression in individuals with cancer. They are present in most individuals with cancer and because of their potent immune suppressive activity are a major deterrent to natural anti-tumor immunity and a significant obstacle to immunotherapy.
authors.affiliation: Dept. of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States. Electronic address: srosenbe@umbc.edu.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Ostrand-Rosenberg
mesh_terms: D000818:Animals; D002417:Cattle; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D007108:Immune Tolerance; D007165:Immunosuppression Therapy; D007167:Immunotherapy / Q000266:history; D022423:Myeloid Cells / Q000276:immunology*; D009369:Neoplasms / Q000276:immunology*; D019139:Tumor Escape; D059016:Tumor Microenvironment / Q000276:immunology*
keywords: Immune suppression; MDSC; Myeloid-derived suppressor cells; Tolerance; Tumor immunology