Elucidating the regulation of T cell subsets (review).

CD4-positive T lymphocytes mainly direct immune as well as autoimmune responses against a variety of pathogens or allergens. This is achieved through the acquisition of specialized functions followed by differentiation into various T cell subsets. The differentiation process of naive T cells into effector subsets is regulated by dendritic cells and secreted cytokines. Signal transducer and activator of transcription proteins play critical roles in transmitting cytokine-mediated signals and specifying T cell differentiation. Epigenetic changes such as histone acetylation and methylation along with DNA methylation also regulate expression of differentiation-specific genes. Defining exactly how extrinsic signals control the specification of T cells will provide important insights and therapeutic opportunities.