title: Structure and function of programmed death (PD) molecules.
abstract: Programmed death (PD) molecules belong to the B7 family of co-stimulatory proteins and function in adaptive immunity. PD-1 (CD279) is expressed on lymphocytes and macrophages, and its ligand (PD-L1, CD274) on immune cells and non-hematopoietic cells. Ligation of PD-1 on lymphocytes inhibits T-cell proliferation, cytokine production, and cytolytic function by phosphorylation of immunoreceptor tyrosine-based switch motifs and blockade of T cell receptor signaling. PD-1 and PD-L1 interactions are essential to maintain peripheral immune tolerance and to modulate activation of naïve T cells. Decreased expression results in autoimmunity in mouse models, and increased expression is a key feature of chronic viral infections in humans.
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Folkl
authors.forename: D
authors.initials: D
authors.lastname: Bienzle
mesh_terms: D056704:Adaptive Immunity / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D008214:Lymphocytes / Q000502:physiology / Q000821:virology; D008264:Macrophages / Q000502:physiology / Q000821:virology; D051379:Mice; D015398:Signal Transduction / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology / Q000821:virology; D014777:Virus Diseases / Q000276:immunology / Q000821:virology
chemical_list: D051017:Apoptosis Regulatory Proteins