The PD-1/PD-L1 pathway in human pathology

Curr Mol Med. 2012 Mar;12(3):259-67. doi: 10.2174/156652412799218903.


T-cell activation is dependent on signals delivered through the antigen-specific T-cell receptor and accessory receptors on T-cells. Integration of signals through this family of costimulatory and inhibitory receptors and their ligands regulates the balance between T-cell activation, tolerance, and immunopathology. Programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, deliver inhibitory signals and exert a vital and diverse range of immunoregulatory roles in T-cell activation, tolerance, and immune-mediated tissue damage. In this review, we revisit current understanding of the immunoregulatory functions of PD-1 and its ligands and their involvement in immune-mediated diseases.

Publication types

  • Review

MeSH terms

  • Alzheimer Disease / immunology
  • Alzheimer Disease / metabolism
  • B7-H1 Antigen / immunology*
  • B7-H1 Antigen / metabolism
  • HIV Infections / immunology
  • HIV Infections / metabolism
  • Humans
  • Immune Tolerance / physiology
  • Multiple Sclerosis / immunology
  • Multiple Sclerosis / metabolism
  • Programmed Cell Death 1 Receptor / immunology*
  • Programmed Cell Death 1 Receptor / metabolism


  • B7-H1 Antigen
  • CD274 protein, human
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor