The inducible costimulator (ICOS) is a new member of the CD28/CD152 receptor family that regulates T-cell activation and function. ICOS binds to a specific ligand on antigen-presenting cells (APC) and cells of the peripheral tissue different from the CD28/CD152 ligands CD80 and CD86. ICOS-L can be induced by inflammatory stimuli in peripheral tissue and on some APC, including monocytes, but is downregulated in B-cell and myeloid leukemia. ICOS-L delivers distinct signals to T cells, presumably important for the maintenance of certain types of immune response, providing the rationale for the development of new therapeutic strategies for the treatment of diseases.
Copyright 2004 S. Karger GmbH, Freiburg