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CD154
Protein-coding gene in humans / From Wikipedia, the free encyclopedia
CD154, also called CD40 ligand or CD40L, is a protein that is primarily expressed on activated T cells[5] and is a member of the TNF superfamily of molecules. It binds to CD40 on antigen-presenting cells (APC), which leads to many effects depending on the target cell type. In total CD40L has three binding partners: CD40, α5β1 integrin and integrin αIIbβ3. CD154 acts as a costimulatory molecule and is particularly important on a subset of T cells called T follicular helper cells (TFH cells).[6] On TFH cells, CD154 promotes B cell maturation and function by engaging CD40 on the B cell surface and therefore facilitating cell-cell communication.[7] A defect in this gene results in an inability to undergo immunoglobulin class switching and is associated with hyper IgM syndrome.[8] Absence of CD154 also stops the formation of germinal centers and therefore prohibiting antibody affinity maturation, an important process in the adaptive immune system.