The biology of interleukin-2.
Much data support an essential role for interleukin (IL)-2 in immune tolerance. This idea is much different from the early paradigm in which IL-2 is central for protective immune responses. This change in thinking occurred when a T regulatory cell defect was shown to be responsible for the lethal autoimmunity associated with IL-2/IL-2R deficiency. This realization allowed investigators to explore immune responses in IL-2-nonresponsive mice rendered autoimmune-free. Such studies established that IL-2 sometimes contributes to optimal primary immune responses, but it is not mandatory. Emerging findings, however, suggest an essential role for IL-2 in immune memory. Here, the current understanding of the dual role of IL-2 in maintaining tolerance and contributing to immunity in vivo is reviewed with some emphasis on T regulatory cell production and homeostasis. Also discussed are implications of this new appreciation concerning the immunobiology of IL-2 with respect to targeting IL-2 or its receptor in immunotherapy.
Department of Microbiology and Immunology and the Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, Florida 33101, USA. tmalek@med.miami.edu
Thomas R
TR
Malek
D000818:Animals; D015551:Autoimmunity / Q000502:physiology; D006801:Humans; D007109:Immunity / Q000502:physiology*; D007156:Immunologic Memory / Q000502:physiology; D007167:Immunotherapy; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000502:physiology* / Q000627:therapeutic use; D015375:Receptors, Interleukin-2 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000502:physiology
D007376:Interleukin-2; D015375:Receptors, Interleukin-2