IL-17-producing γδ T cells and innate lymphoid cells

Eur J Immunol. 2012 Sep;42(9):2221-31. doi: 10.1002/eji.201242569.


The inflammatory cytokine IL-17 plays a critical role in immunity to infection and is involved in the inflammatory pathology associated with certain autoimmune diseases, such as psoriasis and rheumatoid arthritis. While CD4(+) and CD8(+) T cells are important sources of this cytokine, recent evidence has suggested that γδ T cells and a number of families of innate lymphoid cells (ILCs) can secrete IL-17 and related cytokines. The production of IL-17 by γδ T cells appears to be largely independent of T-cell receptor activation and is promoted through cytokine signalling, in particular by IL-23 in combination with IL-1β or IL-18. Therefore IL-17-secreting γδ T cells can be categorised as a family of cells similar to innate-like lymphoid cells. IL-17-secreting γδ T cells function as a part of mucosal defence against infection, with most studies to date focusing on their response to bacterial pathogens. γδ T cells also play a pathological role in certain autoimmune diseases, where they provide an early source of IL-17 and IL-21, which initiate responses mediated by conventional IL-17-secreting CD4(+) T cells (Th17 cells). ILCs lack an antigen receptor or other lineage markers, and ILC subsets that express the transcriptional factor RORγt have been found to secrete IL-17. Evidence is emerging that these newly recognised sources of IL-17 play both pathological and protective roles in inflammatory diseases as discussed in this article.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Humans
  • Inflammation / immunology
  • Interleukin-17 / biosynthesis*
  • Interleukin-17 / immunology
  • Lymphocytes / immunology*
  • Receptors, Antigen, T-Cell, gamma-delta / immunology*
  • T-Lymphocyte Subsets / immunology*


  • Interleukin-17
  • Receptors, Antigen, T-Cell, gamma-delta