PD-L1 (also known as CD274 and B7-H1), one of the ligands for programmed death 1 (PD-1), is an immune-inhibitory receptor belonging to the CD28/cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) family. It can deliver an inhibitory signal to T cells expressing PD-1/B7-1, resulting in immune suppressive effects. PD-L1 is expressed on activated T cells, B cells, NK cells, DCs, macrophages, and bone marrow-derived mast cells. PD-L1 expression is also found on a wide range of human tumors. In addition, studies have show that PD-L1 expression strongly correlates with unfavorable prognosis in kidney, ovarian, bladder, breast, liver, gastric, and pancreatic cancer, but not in non-small cell lung cancer (NSCLC). Most important, these studies reveal that higher expression of PD-L1 may facilitate advancement of tumor stage and increase the invasion potential. PD-L1 expression can be induced by many inflammatory mediators and cytokines, of which interferon-γ (IFN-γ) is the most potent.
Anti-Human CD274/PD-L1 (29E.2A3)-148Nd—100 Tests