CD134, also known as OX40 and TNFRSF4, is a 50 kDa type I transmembrane glycoprotein. It is a member of the tumor necrosis factor receptor superfamily (TNFRSF). OX40 is expressed on activated T lymphocytes, including Th1, Th2, Th17, and Treg cell subsets. The interaction between OX40 and its ligand OX40L (TNFSF4) induces B cell proliferation and antibody secretion, and modulates primary T cell expansion and T cell survival. Furthermore, OX40 influences the size of the T cell memory pool and modulates CD4+ T cell tolerance.
