PD-L1/4-1BBL Antibodies

Target Information

Programmed death receptor ligand 1 (PD-L1, also called B7-H1) is a recently described B7 family member. To date, one specific receptor has been identified that can be ligated by PD-L1. This receptor, programmed death receptor 1 (PD-1), has been shown to negatively regulate T-cell receptor (TCR) signaling. Upon ligating its receptor, PD-L1 has been reported to decrease TCR-mediated proliferation and cytokine production. PD-L1 expression was found to be abundant on many murine and human cancers and could be further up-regulated upon IFN-gamma stimulation. Thus, PD-L1 might play an important role in tumor immune evasion.

CD137 ligand (CD137L) is a type II membrane protein and part of the TNF superfamily. CD137L is a co-stimulatory molecule that is expressed on antigen presenting cells (DCs, monocytes/macrophages, B cells) and is upregulated upon activation. Its receptor, CD137/4-1BB, is found on a variety of cells, including inflamed endothelial cells, where its expression enhances extravasation of CD137L expressing monocytes. Activated T cells also express CD137, and engagement with CD137L enhances T cell proliferation, IL-2 secretion, survival, and cytotoxic activity. CD137L is also expressed on a majority of B-cell lymphomas, including mantle cell lymphoma, follicular lymphoma, and diffuse large B-cell lymphoma (but it is lacking on Hodgkin lymphoma and T-cell lymphoma). CD137L is also expressed in carcinoma cell lines, and is thought to be involved in T cell-tumor cell interactions.