CD274 and inflammatory bowel disease: Programmed death-ligand 1 (PD-L1)—also known as cluster of differentiation 274 (CD274) or as B7 homolog 1 (B7-H1)—is a protein encoded by the CD274 gene and promotes the secretion of proinflammatory cytokines, including TNF-α and IFN-γ, by DCs of IBD patients, which play an essential role in the pathogenesis of these diseases.