Current studies in the Cantor lab have begun to define regulatory T cell lineages that inhibit the development of autoimmune disease and may regulate anti-viral and anti-tumor immunity. More recent studies have suggested that expression of the Helios transcription factor by Treg ensures a stable inhibitory phenotype and maintenance of self tolerance in the face of inflammatory and infectious challenge. We are currently studying non-classical CD8+ T-cells that recognize viral peptides presented by class Ib MHC molecules, termed MHC-E, in efforts to define their contribution to protective anti-viral and anti-tumor immunity in the face of class Ia MHC immune evasion. Additional studies focus on discovery of genetic and epigenetic targets that control the tumor microenvironment, and the potential contribution of cells of the immune system to Alzheimer's Disease. We believe that increased understanding of these cellular and molecular mechanisms will be essential to craft more effective approaches to vaccine design and immunotherapy.