title: PD-L1 and PD-L2 differ in their molecular mechanisms of interaction with PD-1.
abstract: The programmed death-1 (PD-1) molecule is involved in peripheral tolerance and in the immune escape mechanisms during chronic viral infections and cancer. PD-1 interacts with two ligands, PD-L1 and PD-L2. We have investigated the molecular mechanisms of PD-1 interactions with its ligands by surface plasmon resonance and cell surface binding as well as the ability of the two ligands to compete for PD-1 binding. PD-L1 and PD-L2 bound PD-1 with comparable affinities, but striking differences were observed at the level of the association and dissociation characteristics. PD-L1, but not PD-L2, had a delayed interaction reminiscent of a phenomenon of conformational transition. These mechanisms were confirmed by using PD-L1 mAbs that delayed the dissociation of PD-L1 from PD-1. This mechanism was not restricted to PD-1 binding since PD-L1 behaved in a similar manner with its second ligand, CD80. Finally, we could demonstrate that PD-L1 and PD-L2 competed for PD-1 binding and conversely, an antagonist PD-1 mAb blocked both PD-L1 and PD-L2 binding to PD-1 and strongly enhanced T-cell proliferation. These data further emphasize the differential molecular mechanisms of interaction of PD-L1 and PD-L2 with PD-1, and suggest possible new approach for the therapy of chronic infection, cancer and transplantation.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Unité 891, Centre de Recherche en Cancérologie de Marseille, Marseille, France.
authors.forename: Marguerite
authors.initials: M
authors.lastname: Ghiotto
authors.forename: Laurent
authors.initials: L
authors.lastname: Gauthier
authors.forename: Nacer
authors.initials: N
authors.lastname: Serriari
authors.forename: Sonia
authors.initials: S
authors.lastname: Pastor
authors.forename: Alemseged
authors.initials: A
authors.lastname: Truneh
authors.forename: Jacques A
authors.initials: JA
authors.lastname: Nunès
authors.forename: Daniel
authors.initials: D
authors.lastname: Olive
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000276:immunology*; D060890:B7-H1 Antigen; D049109:Cell Proliferation; D003713:Dendritic Cells / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000276:immunology*; D016133:Polymerase Chain Reaction; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D011485:Protein Binding; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D051017:Apoptosis Regulatory Proteins; D060890:B7-H1 Antigen; C423236:CD274 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C105992:PDCD1 protein, human; C556977:PDCD1LG2 protein, human; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor