IL-21 and IL-21 receptor: a new cytokine pathway modulates innate and adaptive immunity

Immunol Res. 2003;28(2):131-40. doi: 10.1385/IR:28:2:131.


Interleukin (IL)-21 is a new member of the type I cytokine superfamily. Although it is most homologous to IL-15, it has a unique receptor chain, IL-21R, that pairs with the gamma-common cytokine receptor chain. The first experiments examining the biology of the IL-21 pathway reveal that it is a cytokine with effects on natural killer (NK) cells, T cells, and B cells. Mice deficient in the IL-21R have also been made, and are being examined for the effects of the IL-21/IL-21R pathway in vivo. Here we summarize our current knowledge of this new cytokine pathway, and its role in innate and adaptive immunity.

Publication types

  • Review

MeSH terms

  • Animals
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism*
  • Humans
  • Interleukin-15 / genetics
  • Interleukin-15 / immunology
  • Interleukin-21 Receptor alpha Subunit
  • Interleukins / immunology
  • Interleukins / metabolism*
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism*
  • Mice
  • Mice, Knockout
  • Receptors, Interleukin / immunology
  • Receptors, Interleukin / metabolism*
  • Receptors, Interleukin-21
  • Signal Transduction / immunology
  • Signal Transduction / physiology
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism*
  • Transcription Factors / immunology
  • Transcription Factors / metabolism


  • IL21R protein, human
  • Il21r protein, mouse
  • Interleukin-15
  • Interleukin-21 Receptor alpha Subunit
  • Interleukins
  • Receptors, Interleukin
  • Receptors, Interleukin-21
  • Transcription Factors
  • interleukin-21