CD40 ligand
protein-coding gene in the species Homo sapiens
CD40 ligand (CD40-L), also commonly called CD154, is a protein that in humans is encoded by the CD40LG gene. CD40-L is primarily expressed on activated T cells 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). On TFH cells, CD154 promotes B cell maturation and function by engaging CD40 on the B cell surface and therefore facilitating cell-cell communication. A defect in this gene results in an inability to undergo immunoglobulin class switching and is associated with hyper IgM syndrome. Absence of CD154 also stops the formation of germinal centers and therefore prohibits antibody affinity maturation, an important process in the adaptive immune system.
History
In 1991, three groups reported discovering CD154. Seth Lederman, Michael Yellin, and Leonard Chess at Columbia University generated a murine monoclonal antibody, 5c8, that inhibited contact-dependent T cell helper function in human cells and which characterized a 32 kDa surface protein transiently expressed on activated CD4+ T cells.
Begin with the source’s own compact description: “CD40 ligand” is protein-coding gene in the species Homo sapiens. The dossier treats that line as a proposition to test through CD40, ligand and protein-coding, not as a finished interpretation.
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Sep 16, 2026. The linked authority identifier is Q14897851. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1991.
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This entry incorporates text from “CD40 ligand” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.