title: The role of natural killer cells, gamma delta T-cells and other innate immune cells in spondyloarthritis.
abstract: OBJECTIVE
  Natural killer (NK) cells, gamma delta (γδ) T-cells and other innate immune cells are important lymphocyte subsets able both to produce cytokines including the pro-inflammatory cytokine IL-17 and to kill cellular targets. This review describes the features of NK cells, γδ T-cells and other innate immune cells, and outlines the evidence for their potential pathogenic roles in spondyloarthritis (SpA).
  
  
  RESULTS
  NK cells and T cells both express receptors that recognize aberrantly folded human leucocyte antigen. This interaction seems to polarize towards a type 17 immunity programme which has been increasingly implicated in SpA pathology. γδ T-cells have also been shown to be polarized towards a type 17 immunity programme in SpA. Gut interactions with the microbiome can influence NK and innate lymphoid immune responses in SpA and other related diseases. A newly identified population of resident lymphoid cells at the enthesis for the first time offers an explanation for the anatomical localization of SpA.
  
  
  CONCLUSIONS
  NK cells, γδ T-cells and other innate immune cells are capable of sharing expression of both transcription factors, including RORγt, and cell surface receptors, such as the killer immunoglobulin-like receptors. There is increasing genetic and functional evidence that they contribute to the RORγt-driven inflammatory type 17 immune responses, and they may link gut inflammation and joint pathology in SpA.
authors: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Headington, Oxford, UK. hussein.al-mossawi@ndorms.ox.ac.uk
authors: Mohammad H
authors: MH
authors: Al-Mossawi
authors: Anna
authors: A
authors: Ridley
authors: Sarah
authors: S
authors: Kiedel
authors: Paul
authors: P
authors: Bowness
mesh_terms: D006801:Humans; D007113:Immunity, Innate; D020381:Interleukin-17 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology*; D064307:Microbiota / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*; D025241:Spondylarthritis / Q000276:immunology* / Q000382:microbiology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D020381:Interleukin-17; D016692:Receptors, Antigen, T-Cell, gamma-delta