Uses
OX40L or tumor necrosis factor superfamily member 4 (TNFSF4), which is a member of the TNF superfamily of structurally related proteins, exists primarily as a type II membrane bound, non-covalently linked homotrimeric protein. This cytokine is expressed on antigen presenting cells (APCs), such as dendritic cells and activated B-cells, and also on various other cells such as vascular endothelial cells, mast cells, and natural killer cells. It has a 23 amino acid cytoplasmic tail and a 133 amino acid extracellular domain. The gene encoding this protein is localized on human chromosome 1q25 and has three exons. Recombinant OX40L is a glycosylated 133 amino acid protein corresponding to the extracellular TNF homologous domain of the full length transmembrane protein. It migrates with an apparent molecular mass of 15.5-25kDa on SDS-PAGE.
Biological Activity
OX40L signals specifically through the OX40 receptor, which is expressed predominantly on CD4+T cells but also on certain activated CD8+T cells. OX40/OX40L functions as a costimulatory signal, which is required for a productive interaction between antigen presenting cells and their target T-cells. It enhances cell proliferation and survival, and increases expression of regulated on activation, normal T cell expressed and secreted (RANTES) or chemokine ligand 5 (CCL5), interleukins-2 and -3, and interferon-γ (IFNγ). OX40/OX40L signaling plays an important role in immuno-regulatory communication and immune-tolerance. Polymorphisms in the TNFSF4 gene have been associated with autoimmune thyroid diseases (AITDs), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc).
