title: Specific and high-affinity binding of tetramerized PD-L1 extracellular domain to PD-1-expressing cells: possible application to enhance T cell function.
abstract: The negative co-stimulatory receptor, programmed cell death 1 (PD-1), is induced on activated T cells and delivers inhibitory signals upon engagement with its ligands PD-L1 and PD-L2, which are expressed on various somatic cells and certain cancers. Accumulating evidence suggests that interfering with the PD-1-PD-L1 interaction may result in the restoration of defective T cell functions in cancer and chronic viral infection. Herein, we established procedures to produce large amounts of renatured recombinant extracellular domain proteins of mouse PD-1 (mPD-1) and PD-L1. While monomeric mPD-1 and mouse PD-L1 (mPD-L1) only marginally interacted with the cells expressing their counterpart proteins, their tetramerization markedly enhanced the affinity with the K(d) of mPD-L1 tetramer being nearly 100-fold lower than that of the corresponding monomer. The affinity of mPD-L1 tetramer was even higher than a high-affinity anti-PD-1 mAb, and it efficiently inhibited the binding of mPD-L1/Fc-chimeric protein to mPD-1(+) cells. Functionally, mPD-L1 tetramer significantly enhanced the proliferative responses as well as the cytotoxic activity of T cells against specific target cells in vitro. The results suggest that oligomeric PD-L1 extracellular domains may provide a potential means to restore T cell functions in cancer and viral infection in humans.
authors.affiliation: Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-Ku, Kyoto 606-8501, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Terawaki
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Nagakura
authors.forename: Tamon
authors.initials: T
authors.lastname: Hayashi
authors.forename: Shiro
authors.initials: S
authors.lastname: Shibayama
authors.forename: Kaori
authors.initials: K
authors.lastname: Muroi
authors.forename: Taku
authors.initials: T
authors.lastname: Okazaki
authors.forename: Bunzo
authors.initials: B
authors.lastname: Mikami
authors.forename: David N
authors.initials: DN
authors.lastname: Garboczi
authors.forename: Tasuku
authors.initials: T
authors.lastname: Honjo
authors.forename: Nagahiro
authors.initials: N
authors.lastname: Minato
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D018122:B7-1 Antigen / Q000378:metabolism*; D060890:B7-H1 Antigen; D002460:Cell Line; D002478:Cells, Cultured; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D010455:Peptides / Q000378:metabolism*; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D051017:Apoptosis Regulatory Proteins; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; C498919:Cd274 protein, mouse; D008562:Membrane Glycoproteins; C556977:PDCD1LG2 protein, human; C491383:Pdcd1 protein, mouse; C556978:Pdcd1lg2 protein, mouse; D010455:Peptides; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D011994:Recombinant Proteins