Description
CD40, also known as TNFRSF5, is a member of the TNF receptor superfamily which are single transmembrane-spanning glycoproteins.plays an essential role in mediating a broad variety of immune and inflammatory responses including T cell-dependent immunoglobulin class switching, memory B cell development, and germinal center formation.CD40 is a costimulatory protein found on antigen presenting cells and is required for their activation, and is expressed in B cells, dendritic cells, macrophages, endothelial cells, and several tumor cell lines.Interaction of CD40 with its ligand, CD40L, leads to aggregation of CD40 molecules,which in turn interact with cytoplasmic components to initiate signaling pathways. Early studies on the CD40-CD40L system revealed its role in humoral immunity. Defects in CD40 result in hyper-IgM immunodeficiency type 3 (HIGM3).