Provided are antibodies that specifically bind to Programmed Death-1 (PD1, Pdcd-1, or CD279) and inhibit PD1-mediated cellular signaling and activities in immune cells, antibodies binding to a set of amino acid residues required for its ligand binding, and uses of these antibodies to treat or diagnose cancer, infectious diseases or other pathological disorders modulated by PD1-mediated functions.本發明提供特異性結合至程序性死亡-1(PD1、Pdcd-1或CD279)及抑制免疫細胞中PD1媒介的細胞訊息傳導及活性的抗體，結合至需要配位體結合之胺基酸殘基之集合的抗體，及該等抗體治療或診斷由PD1媒介功能所調變的癌症、傳染性疾病或其他病理失調症之用途。
