CD154

CD154, also known as CD40 ligand or CD40L, is a protein that is primarily expressed on activated T cells and is part 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 general, CD40L plays the role of a costimulatory molecule and induces activation in APC in association with T cell receptor stimulation by MHC molecules on the APC. In addition to its expression on T cells, CD40L is also found on platelets, mast cells, and basophils.

Function

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, CD40L promotes B cell maturation and function by engaging CD40 on the B cell surface and therefore facilitating cell-cell communication. CD154 expression on Tfh cells is necessary for their development, maintenance, and function.

Clinical significance

Mutations in this gene result in Hyper IgM syndrome, where its absence prevents the immune system from switching from making antibodies of the IgM type to antibodies of other types. It is also involved in the pathophysiology of many autoimmune diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis).

See also

• Cluster of differentiation
• CD40 (protein)
• Hyper IgM syndrome

External links

• CD154 at the US National Library of Medicine Medical Subject Headings (MeSH)

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