Background：CD134, also known as OX40 and TNFRSF4, is a 50 kD type I transmembrane glycoprotein. It is a member of the TNF receptor family. OX40 is expressed on activated T lymphocytes including Th1, Th2, Th17, and Treg cells. The interaction of OX40 with OX40L results in B cell proliferation and antibody secretion, regulation of primary T cell expansion, and T cell survival. OX40 influences the size of the T cell memory pool and regulation of CD4+ T cell tolerance.
