title: Differential expression of PD-L1 and PD-L2, ligands for an inhibitory receptor PD-1, in the cells of lymphohematopoietic tissues.
abstract: PD-1 is a member of the immunoglobulin superfamily expressed on immune cells, including T and B cells, and is involved in the delivery of inhibitory signal upon engagement of its ligands, PD-L1 and PD-L2. While the expression profile of PD-1 has been well documented, the analysis of PD-L1 and PD-L2 distributions on a protein basis has not been carried out because of the lack of available monoclonal antibodies specific for the molecules. In this study, we established two monoclonal antibodies, 1-111A and 122, specific for murine PD-L1 and PD-L2, respectively, and examined their expression profiles. Based on flow cytometric analyses, the expression of PD-L1 was detected in a variety of lymphohematopoietic cell types, including a minor proportion of T and B cells in the spleen, majority of pre-B cells and myeloid cells in bone marrow and subsets of thymocytes, while the expression of PD-L2 was not observed in the lymphohematopoietic cells at all. Notably, a significant proportion of the most immature lineage-marker-negative and c-Kit-positive bone marrow cells containing stem cells did express PD-L1. Following mitogenic stimulation, essentially all lymphocytes expressed PD-L1. Furthermore, a variety of leukemic lines also expressed PD-L1, while none of them did PD-L2. Thus, present results demonstrate the distinct expression patterns of PD-L1 and PD-L2 with the cells of lymphohematopoietic tissues exclusively expressing the former.
authors.affiliation: Laboratory of Immunology and Cell Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Ishida
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Iwai
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Taku
authors.initials: T
authors.lastname: Okazaki
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Freeman
authors.forename: Nagahiro
authors.initials: N
authors.lastname: Minato
authors.forename: Tasuku
authors.initials: T
authors.lastname: Honjo
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000378:metabolism*; D051017:Apoptosis Regulatory Proteins; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D001798:Blood Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000276:immunology* / Q000378:metabolism*; D002454:Cell Differentiation; D005260:Female; D015870:Gene Expression; D008024:Ligands; D008213:Lymphocyte Activation; D008221:Lymphoid Tissue / Q000276:immunology* / Q000378:metabolism*; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D051017:Apoptosis Regulatory Proteins; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D001798:Blood Proteins; C498919:Cd274 protein, mouse; D008024:Ligands; D008562:Membrane Glycoproteins; C491383:Pdcd1 protein, mouse; C556978:Pdcd1lg2 protein, mouse; D010455:Peptides; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor