Mouse OX40 Antibody

OX40, also known as CD134, was originally identified as an activated rat CD4⁺ T cell-surface antigen that is recognized by the monoclonal antibody MRC OX40. It is a member of the tumor necrosis factor receptor superfamily (TNFRSF) and has been designated TNFRSF4. Mouse OX40 cDNA encodes a 256 amino acid (aa) residues type I transmembrane precursor protein with a putative 19 aa signal peptide, a 192 aa extracellular domain containing 4 TNFR-cysteine rich repeats, a 25 aa transmembrane domain and a 36 aa cytoplasmic region. A naturally occurring soluble OX40 has also been identified in human serum. Mouse OX40 shares approximately 63% and 90% aa sequence identity with its human and rat counterparts, respectively. OX40 is a T cell activation antigen that is expressed primarily on activated CD4⁺ T cells, but is also expressed on activated human and mouse CD8⁺ T cells. The ligand of OX40 is OX40 ligand (OX40L), also known as gp34, a type II transmembrane glycoprotein belonging to the TNF superfamily. OX40L is expressed on activated B cells, T cells, dendritic cells and endothelial cells. Ligation of OX40 on T cells by OX40L or an agonistic antibody can promote clonal expansion, long-term T cell survival, and enhance memory T cell development. In vivo, blockade of OX40/OX40L interaction has been useful for treating autoimmune disease and graft-versus-host disease in animal models. Activation of OX40 has also been utilized to enhance the potency of vaccines and augment anti-tumor immunity (1-9).