Anti-PD-1 antibodies are immunodetection reagents that target the PD-1 antigen. PD-1 is an alias name for the protein, programmed cell death 1, encoded by the gene PDCD1 in humans. PD-1 functions in immune response and T cell self-regulation. When bound to its regulator PD-L1, the PD-1 receptor suppresses T cell inflammatory activity, preventing it from killing other host cells. For its role in inhibiting T cell response, PD-1 is a notable cancer immunotherapy target.