title: PD-1 regulates self-reactive CD8+ T cell responses to antigen in lymph nodes and tissues.
abstract: PD-1, an inhibitory receptor expressed on activated lymphocytes, regulates tolerance and autoimmunity. We tested the role of PD-1:PD-1 ligand (PD-L) interactions in cross-presentation and the generation and control of CD8(+) responses against self-Ag. Ag-naive PD-1(-/-) OVA-specific OT-I CD8(+) T cells exhibited exacerbated responses to cross-presented Ag in mice expressing soluble OVA under the control of the rat insulin promoter (RIP-ova(high)). Following adoptive transfer into RIP-ova(high) recipients, PD-1(-/-) OT-I T cells expanded in the pancreatic lymph node. In contrast to wild-type OT-I cells, PD-1(-/-) OT-I T cells secreted IFN-gamma and migrated into the pancreas, ultimately causing diabetes. Loss of PD-1 affected CD8(+) cells intrinsically, and did not significantly alter the responses of wild-type OT-I T cells adoptively transferred into the same RIP-ova(high) recipient mouse. PD-1:PD-L interactions also limited CD8(+) effector cells, and PD-L1 expression on parenchymal tissues protected against effector OT-I T cell attack. Finally, we found that the loss of PD-1 on effector OT-I cells lowers the threshold for Ag recognition in peripheral tissues. These findings indicate two checkpoints where PD-1 attenuates self-reactive T cell responses: presentation of self-Ag to naive self-reactive T cells by dendritic cells in the draining lymph node and reactivation of pathogenic self-reactive T cells in the target organ.
authors.affiliation: Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Keir
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Freeman
authors.forename: Arlene H
authors.initials: AH
authors.lastname: Sharpe
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology* / Q000378:metabolism; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018122:B7-1 Antigen / Q000378:metabolism; D060890:B7-H1 Antigen; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D045142:Cross-Priming / Q000276:immunology; D008198:Lymph Nodes / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010047:Ovalbumin / Q000276:immunology; D010179:Pancreas / Q000276:immunology / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D061026:Programmed Cell Death 1 Receptor; D017634:Self Tolerance
chemical_list: D000941:Antigens; D000954:Antigens, Surface; D051017:Apoptosis Regulatory Proteins; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; C498919:Cd274 protein, mouse; D008562:Membrane Glycoproteins; C491383:Pdcd1 protein, mouse; D010455:Peptides; D061026:Programmed Cell Death 1 Receptor; D010047:Ovalbumin