title: Interleukin 21: a key player in lymphocyte maturation.
abstract: The common gamma chain family of cytokine receptors plays a plethora of roles during the early development, activation, and terminal differentiation of the lymphocyte lineages. The most recently identified member of this family, the IL-21R, is expressed to varying degrees on B, T lymphocytes, and natural killer (NK) cells, whereas IL-21, is reportedly only produced by activated CD4+ T cells. In keeping with this expression pattern the IL-21:IL-21R interaction is important for the latter stages and function of all three lymphoid lineages. IL-21 is a regulator of A-cell differentiation to plasma cells as well as immunoglobulin class switching. In contrast, within the T-cell lineage, IL-21 acts as a co-stimulator of proliferation, enhances memory response, and modulates homeostasis. Within the innate immune system IL-21 has a role in the terminal differentiation of NK cells, enhancing cytotoxic function while also decreasing cellular viability. These immune maturation and stimulating functions have resulted in IL-21 being tested in a variety of models of immunity. In these contexts, IL-21 has shown very promising efficacy in a number of antitumor immune responses mediated by NK and or T lymphocytes.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville Victoria 3050, Australia. nutt@wehi.edu.au
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Nutt
authors.forename: Jason
authors.initials: J
authors.lastname: Brady
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hayakawa
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Smyth
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology*; D006801:Humans; D053738:Interleukin-21 Receptor alpha Subunit; D007378:Interleukins / Q000235:genetics / Q000276:immunology*; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology*; D051379:Mice; D018448:Models, Immunological; D010950:Plasma Cells / Q000166:cytology / Q000276:immunology; D018123:Receptors, Interleukin / Q000235:genetics / Q000276:immunology; D053655:Receptors, Interleukin-21; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology; D000098546:Interleukin-21
chemical_list: C508117:IL21R protein, human; C508118:Il21r protein, mouse; D053738:Interleukin-21 Receptor alpha Subunit; D007378:Interleukins; D018123:Receptors, Interleukin; D053655:Receptors, Interleukin-21; D000098546:Interleukin-21