The biology of interleukin-2

Annu Rev Immunol. 2008:26:453-79. doi: 10.1146/annurev.immunol.26.021607.090357.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Autoimmunity / physiology
  • Humans
  • Immunity / physiology*
  • Immunologic Memory / physiology
  • Immunotherapy
  • Interleukin-2 / antagonists & inhibitors
  • Interleukin-2 / physiology*
  • Interleukin-2 / therapeutic use
  • Receptors, Interleukin-2 / agonists
  • Receptors, Interleukin-2 / antagonists & inhibitors
  • Receptors, Interleukin-2 / physiology
  • T-Lymphocytes, Regulatory / cytology
  • T-Lymphocytes, Regulatory / physiology


  • Interleukin-2
  • Receptors, Interleukin-2