CD154

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Crystal structure of human CD40L
CD40L (CD154) molecule
Identifiers
Symbol	CD40L, CD40LG, CD154
HUGO	11935
Entrez	959
OMIM	300386
RefSeq	NM_000074
UniProt	P29965
PDB	1ALY
Other data
Locus	Chr. X q26

CD154, also called CD40 ligand or CD40L, is a protein that is primarily expressed on activated T cells and is a member of the TNF family 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.

1 Expression of CD154
2 Specific effects on cells
- 2.1 Macrophages
- 2.2 B cells
3 References
4 External links

[edit] Expression of CD154

CD40 ligand is primarily expressed on activated CD4+ T lymphocytes but is also found in a soluble form. Whilst CD40L was originally described on T lymphocytes, its expression has subsequently been found on a wide variety of cells, including platelets, mast cells, macrophages, basophils, NK cells, B lymphocytes, as well as non-haematopoietic cells (smooth muscle cells, endothelial cells and epithelial cells)[1].

[edit] Specific effects on cells

[edit] Macrophages

In the macrophage, the primary signal for activation is IFN-γ from Th1 type CD4 T cells. The secondary signal is CD40L on the T cell which binds CD40 on the macrophage cell surface. As a result, the macrophage expresses more CD40 and TNF receptors on its surface which helps increase the level of activation. The activated macrophage can then destroy phagocytosed bacteria and produce more cytokines.

[edit] B cells

The B cell can present antigens to helper T cells. If the T cell recognizes the peptide presented by the B cell, the T cell synthesizes CD40L. The CD40L binds to the B cell's CD40 receptor which causes resting B cell activation. The T cell also produces IL-4 which directly binds to B cell receptors. As a result of this interaction, the B cell can undergo division, antibody isotype switching, and differentiation to plasma cells. The end result is a B cell which is able to mass produce specific antibodies against an antigenic target.