CD40

CD40 is a costimulatory protein found on antigen presenting cells and is required for their activation. The binding of CD40 with CD40 ligand is necessary for a broad variety of immune and inflammatory responses including T cell-dependent immunoglobulin class switching, memory B cell development, and germinal center formation.

Structure

CD40 is a member of the TNF-receptor superfamily. The protein is expressed on B cells, dendritic cells, macrophages, endothelial cells, and epithelial cells. The protein is approximately 50kDa and is expressed on the cell surface as a type I transmembrane protein.

Function

CD40 is necessary for antigen presenting cell activation, which in turn stimulates proliferation and differentiation of B cells, isotype switching, and germinal center formation. CD40 is also important in macrophages and dendritic cells, where it mediates different immune and inflammatory responses.

Clinical significance

Mutations in this gene result in Immunodeficiency with hyper-IgM type 3. An increased expression of CD40 has also been observed in several diseases, including HIV and Epstein-Barr virus, and autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis.

See also

• CD40 ligand
• TNF-receptor superfamily
• Immunodeficiency with hyper-IgM type 3

References

CD40 Resources
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