title: Interleukin-21: a modulator of lymphoid proliferation, apoptosis and differentiation.
abstract: The interleukin-21 (IL-21)-IL-21-receptor system was discovered in 2000. It was immediately of great interest because of the homology of IL-21 to IL-2, IL-4 and IL-15, and of the IL-21-receptor subunit IL-21R to the beta-subunit of the IL-2 receptor, and because the IL-21 receptor also contains the common cytokine-receptor gamma-chain, the protein that is mutated in X-linked severe combined immunodeficiency. As we discuss, IL-21 has pleiotropic actions, from augmenting the proliferation of T cells and driving the differentiation of B cells into memory cells and terminally differentiated plasma cells to augmenting the activity of natural killer cells. Moreover, it has antitumour activity and might have a role in the development of autoimmunity, so these findings have implications for the treatment of cancer and autoimmune diseases.
authors.affiliation: Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892-1674, USA. wjl@helix.nih.gov
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Leonard
authors.forename: Rosanne
authors.initials: R
authors.lastname: Spolski
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology*; D006801:Humans; D007378:Interleukins / Q000502:physiology*; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology*; D000098546:Interleukin-21
chemical_list: D007378:Interleukins; D000098546:Interleukin-21