Recombinant Rat OX40 Ligand/TNFSF4 Protein

OX40 Ligand (OX40L; also known as TNFSF4, CD252, and gp34) is a type II transmembrane glycoprotein belonging to the TNF superfamily (1-3). OX40 Ligand coordinates with other costimulators (B7, CD40 Ligand/TNFSF5, CD30 Ligand/TNFSF8, CD27 Ligand/TNFSF7, and 4-1BB Ligand/TNFSF9) to manage the activation of the immune response. The rat OX40 Ligand cDNA encodes a 199 amino acid (aa) polypeptide with a short amino-terminal cytoplasmic domain and a 151 aa carboxy-terminal extracellular domain (ECD). The rat OX40 Ligand ECD shares 79% and 40% aa sequence identity with mouse and human OX40 Ligand ECD, respectively. OX40 Ligand is expressed on the surface of activated antigen presenting cells, B cells, T cells, and endothelial cells at sites of inflammation (4-6). Similar to other TNF superfamily members, membrane-bound OX40 Ligand is expressed as a homotrimer (7). OX40 Ligand binds to the type 1 transmembrane receptor, OX40, which is expressed on activated T cells. OX40 Ligand-OX40 signaling results in increased T cell survival, proliferation, and cytokine production (8, 9). It also modulates natural killer cell function, inhibits the conversion of effector T cells into immunosuppressive regulatory T cells (Tregs), and promotes the maintenance of and recall response in memory T cells (7-13). OX40 Ligand-OX40 signaling is involved in allergic airway inflammation, graft-versus-host disease, and other autoimmune diseases (14-16). Mutations in OX40 and OX40 Ligand are associated with cardiovascular disease (13, 17).