PD-1 and its ligands in tolerance and immunity.

  title={PD-1 and its ligands in tolerance and immunity.},
  author={Mary E. Keir and Manish J. Butte and Gordon J. Freeman and Arlene H. Sharpe},
  journal={Annual review of immunology},
Programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, deliver inhibitory signals that regulate the balance between T cell activation, tolerance, and immunopathology. Immune responses to foreign and self-antigens require specific and balanced responses to clear pathogens and tumors and yet maintain tolerance. Induction and maintenance of T cell tolerance requires PD-1, and its ligand PD-L1 on nonhematopoietic cells can limit effector T cell responses and protect tissues from immune… 

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