title: Tolerance, not immunity, crucially depends on IL-2.
abstract: Interleukin-2 (IL-2) was identified based on its potent T-cell growth-factor activity and is widely considered to be a key cytokine in T-cell-dependent immune responses. However, the main non-redundant activity of this cytokine centres on the regulation of T-cell tolerance, and recent studies indicate that a failure in the production of CD4(+)CD25(+) regulatory T cells is the underlying cause of autoimmunity in the absence of IL-2. In marked contrast to the importance of IL-2 in peripheral T-cell tolerance, T-cell immunity is readily elicited to various agents in the absence of IL-2 in vivo. Here, we discuss these findings and, in particular, the action of IL-2 on regulatory T cells and effector cells, and the targeting of IL-2 and/or the IL-2 receptor in clinical settings.
authors.affiliation: Department of Microbiology and Immunology, University of Miami School of Medicine, Miami, Florida 33136, USA. tmalek@med.miami.edu
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Malek
authors.forename: Allison L
authors.initials: AL
authors.lastname: Bayer
mesh_terms: D000818:Animals; D002455:Cell Division / Q000276:immunology / Q000502:physiology; D002470:Cell Survival / Q000276:immunology / Q000502:physiology; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology / Q000502:physiology*; D007109:Immunity / Q000276:immunology / Q000502:physiology*; D007376:Interleukin-2 / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology
chemical_list: D007376:Interleukin-2