AHR and autoimmune disease: Most studies suggest that AhR activation in T cells or in antigen presenting cells may increase Treg production and therefore decrease autoimmunity, but the opposite outcome is also likely and possibly ligand-specific; Context-specific activation of the AhR by specific ligands may result in either increased or decreased Treg activity; Sex hormones play an important role in Treg development and may underlie female predominance of autoimmune diseases.