Dictionary of Allergies .. CD40 Antigen

CD40 Antigen

The CD40 antigen is a 277 amino acid, 48KDa glycosylated phosphoprotein which is a member of the new nerve growth factor (NGF) receptor superfamily of transmembrane proteins, defined by cysteine-rich motifs.  CD40 is expressed on B cells from the very early precursors up to the plasma cell stage where its expression is lost.  It is also found on a few other cell types such as follicular dendritic cells, Langerhans cells, dendritic cells and activated macrophages [1].

During the generation of a successful adaptive immune response, multiple molecular signals are required. A primary signal is the binding of cognate antigen to an antigen receptor expressed by T and B lymphocytes. Multiple secondary signals involve the engagement of costimulatory molecules expressed by T and B lymphocytes with their respective ligands. Because of its essential role in immunity, one of the best characterized of the costimulatory molecules is the receptor CD40. This receptor, a member of the tumor necrosis factor receptor family, is expressed by B cells, professional antigen-presenting cells, as well as non-immune cells and tumors. CD40 binds its ligand CD40L, which is transiently expressed on T cells and other non-immune cells under inflammatory conditions. A wide spectrum of molecular and cellular processes is regulated by CD40 engagement including the initiation and progression of cellular and humoral adaptive immunity [2].

Reference

1. Banchereau, J., et al:  Cytokines controlling human B lymphocyte differentiation: impact of the CD40 system.  In Advances in Allergy and Clinical Immunology.  Ed. by Godard Ph. et al.  EAACI XVth European Congress, 10-15 May 1992.
2. Elgueta R, Benson MJ, de Vries VC, Wasiuk A, Guo Y, Noelle RJ. Molecular mechanism and function of CD40/CD40L engagement in the immune system. Immunol Rev. 2009 May;229(1):152-72.