title: The role of IL-21 in regulating B-cell function in health and disease.
abstract: Interleukin-21 (IL-21) belongs to a family of cytokines that includes IL-2, IL-4, IL-7, IL-9, and IL-15, all of which bind to private (or shared) receptors as well as the common cytokine receptor gamma-chain as a component. Most cytokines in this family are critically important for both the maintenance and function of T cells and B cells. The receptor for IL-21 is widely distributed on lymphohematopoietic cells, and IL-21 plays many biologic roles, including maintenance and function of CD8(+) memory T cells and natural killer cells, as well as promoting the generation of Th17 cells in the mouse. One principal non-redundant role of IL-21 is the promotion of B-cell activation, differentiation or death during humoral immune responses. Furthermore, increased IL-21 production is characteristic of certain autoimmune diseases and is likely to contribute to autoantibody production as well as pathologic features of autoimmune disease. In contrast, IL-21 may function as a co-adjuvant to enhance antibody responses and thereby facilitate host defense to malignances and infectious diseases. The critical role of IL-21 in promoting humoral immune responses makes it an important focus of potential therapeutic interventions in conditions characterized by either overproduction of pathogenic autoantibodies or under production of protective antibodies.
authors.affiliation: Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA. ettingerc@medimmune.com
authors.forename: Rachel
authors.initials: R
authors.lastname: Ettinger
authors.forename: Stefan
authors.initials: S
authors.lastname: Kuchen
authors.forename: Peter E
authors.initials: PE
authors.lastname: Lipsky
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D016923:Cell Death / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory; D007378:Interleukins / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D019899:Paracrine Communication / Q000276:immunology; D000098546:Interleukin-21
chemical_list: D007378:Interleukins; D000098546:Interleukin-21