Differential expression of PD-L1 and PD-L2, ligands for an inhibitory receptor PD-1, in the cells of lymphohematopoietic tissues

Immunol Lett. 2002 Oct 21;84(1):57-62. doi: 10.1016/s0165-2478(02)00142-6.


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.

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antigens, Surface / metabolism*
  • Apoptosis Regulatory Proteins
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism
  • B7-1 Antigen*
  • B7-H1 Antigen
  • Blood Proteins / genetics
  • Blood Proteins / immunology
  • Blood Proteins / metabolism*
  • Bone Marrow Cells / immunology*
  • Bone Marrow Cells / metabolism*
  • Cell Differentiation
  • Female
  • Gene Expression
  • Ligands
  • Lymphocyte Activation
  • Lymphoid Tissue / immunology*
  • Lymphoid Tissue / metabolism*
  • Membrane Glycoproteins
  • Mice
  • Mice, Inbred BALB C
  • Peptides / genetics
  • Peptides / immunology
  • Peptides / metabolism*
  • Programmed Cell Death 1 Ligand 2 Protein
  • Programmed Cell Death 1 Receptor
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • Tumor Cells, Cultured


  • Antibodies, Monoclonal
  • Antigens, Surface
  • Apoptosis Regulatory Proteins
  • B7-1 Antigen
  • B7-H1 Antigen
  • Blood Proteins
  • Cd274 protein, mouse
  • Ligands
  • Membrane Glycoproteins
  • Pdcd1 protein, mouse
  • Pdcd1lg2 protein, mouse
  • Peptides
  • Programmed Cell Death 1 Ligand 2 Protein
  • Programmed Cell Death 1 Receptor