Programmed death-ligand 1 (PD-L1) also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1) is a protein that in humans is encoded by the CD274 gene. PD-L1((B7-H1)) is a 40kDa type 1 transmembrane protein that has been speculated to play a major role in suppressing the immune system during particular events such as pregnancy, tissue allografts, autoimmune disease and other disease states such as hepatitis. Normally the immune system reacts to foreign antigens where there is some accumulation in the lymph nodes or spleen which triggers a proliferation of antigen-specific CD8+ T cell. PD-L1(B7-H1) binds to its receptor, PD-1, found on activated T cells, B cells, and myeloid cells, to modulate activation or inhibition. PD-L1(B7-H1) expression is up-regulated in a small fraction of activated T and B cells and a much larger fraction of activated monocytes. PD-L1(B7-H1) expression is also induced in dendritic cells and keratinocytes after IFN-gamma stimulation. Interaction of B7-H1 with PD-1 results in inhibition of TCR-mediated proliferation and cytokine production.
Recombinant Human PD-L1 produced in HEK293 cells is a polypeptide chain containing 227 amino acids with C-terminal 6×His. A fully biologically active molecule, rhPD-L1 has a molecular mass of 31-35 kDa analyzed by reducing SDS-PAGE and is obtained by chromatographic techniques at GenScript.