Anti-programmed death 1 (PD1)

Abstract

Programmed death-1 (PD-1) is a cell-surface receptor expressed on activated T and B cells, NK, NKT cells, and some myeloid cells (Okazaki and Honjo, Int Immunol 19:813-824, 2007; Keir et al., Annu Rev Immunol 26:677-704, 2008). Upon ligand binding, PD-1 delivers an inhibitory signal that attenuates T-cell receptor (TCR) signaling. PD-1 signaling results in reduced T-cell activation and effector function (Okazaki and Honjo, Int Immunol 19:813-824, 2007; Keir et al., Annu Rev Immunol 26:677-704, 2008). The PD-1 ligand PD-L1 is expressed on many tumors and is an important component of the immunosuppressive tumor microenvironment (Brown et al., J Immunol 170:1257-1266, 2003; Dong et al., Nat Med 8:793-800, 2002; Driessens et al., Immunol Rev 229:126-144, 2009; Wang and Chen, Curr Top Microbiol Immunol, n.d.).