Specific and high-affinity binding of tetramerized PD-L1 extracellular domain to PD-1-expressing cells: possible application to enhance T cell function

Int Immunol. 2007 Jul;19(7):881-90. doi: 10.1093/intimm/dxm059. Epub 2007 Jul 2.


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.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Surface / metabolism*
  • Apoptosis Regulatory Proteins / metabolism*
  • B7-1 Antigen / metabolism*
  • B7-H1 Antigen
  • Cell Line
  • Cells, Cultured
  • Lymphocyte Activation
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Peptides / metabolism*
  • Programmed Cell Death 1 Ligand 2 Protein
  • Programmed Cell Death 1 Receptor
  • Protein Binding
  • Protein Structure, Tertiary / physiology
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Spleen / cytology
  • Spleen / metabolism
  • T-Lymphocytes / immunology*


  • Antigens, Surface
  • Apoptosis Regulatory Proteins
  • B7-1 Antigen
  • B7-H1 Antigen
  • Cd274 protein, mouse
  • Membrane Glycoproteins
  • PDCD1LG2 protein, human
  • Pdcd1 protein, mouse
  • Pdcd1lg2 protein, mouse
  • Peptides
  • Programmed Cell Death 1 Ligand 2 Protein
  • Programmed Cell Death 1 Receptor
  • Recombinant Proteins