PDCD1 and ulcerative colitis: <h4>Objectives</h4>To investigate the expression and significance of programmed cell death protein 1 (PD-1) and programmed cell death ligand-1 (PD-L1) in the mucosal tissues and peripheral blood of patients with ulcerative colitis (UC).<h4>Methods</h4>Eighty patients with UC were recruited from January 2021 to August 2022 from the Shanxi Province People's Hospital.