CD40LG

CD40LG, also named as CD40L or CD154, is a member of the TNF superfamily of molecules. Mostly, this protein is expressed on activated T cells and binds to CD40 on antigen-presenting cells (APC), resulting in a number of effects depending on the target cell type. To date, CD40LG possesses three binding partners: α5β1 integrin, CD40, and αIIbβ3. This protein functions as a costimulatory molecule and plays an essential role in a subset of T cells called T follicular helper cells (TFH cells). On TFH cells, CD40LG facilitate B cell maturation and work via engaging CD40 on the B cell surface, hence facilitating cell-cell communication.
Importantly, a defect in this gene leads to an inability to undergo immunoglobulin class switching and is related to hyper IgM syndrome. Also, the absence of CD40LG suspends the generation of germinal centers, thus prohibiting antibody affinity maturation, an important process in the adaptive immune system. Generally, CD40LG is expressed on activated CD4+ T lymphocytes, however, it is also found in a soluble form. Additionally, it is also expressed on a great variety of cells, such as NK cells, mast cells, platelets, B lymphocytes, macrophages, basophils, as well as non-haematopoietic cells (endothelial cells, smooth muscle cells, and epithelial cells).

Gene ID: 959
UniProt ID: P29965