Increased expression of IL-15 in the synovium of patients with rheumatoid arthritis compared with patients with Yersinia-induced arthritis and osteoarthritis

J Pathol. 1997 Apr;181(4):444-50. doi: 10.1002/(SICI)1096-9896(199704)181:4<444::AID-PATH778>3.0.CO;2-O.


Recently, a new player in the cytokine network has been described that is produced by monocytes and can be detected in the rheumatoid synovium: interleukin-15 (IL-15). Since this cytokine may play a role in the accumulation and activation of T-cells, B-cells, and natural killer (NK) cells characteristic of synovial tissue (ST) from patients with rheumatoid arthritis (RA), the expression of IL-15 was studied in ST from RA patients in comparison with ST from patients with reactive arthritis (ReA) and osteoarthritis (OA) and the phenotype of IL-15-positive cells was determined. IL-15 expression was investigated by immunohistochemical analysis of ST from ten patients with RA, ten patients with Yersinia enterocolitica-induced ReA, and nine patients with OA. The immunohistological findings were quantified and the results obtained in the different patient groups were compared. To determine the phenotype of IL-15-expressing cells, double-labelling immunofluorescence was performed. The expression of IL-15 was significantly higher in ST from patients with RA than in ST from patients with ReA or OA. In double-label experiments, co-expression was observed with markers for macrophages, T-cells, and NK cells. The composition of the cellular infiltrate in the synovium of patients with RA might be partly explained by the specific increase in expression of IL-15 in rheumatoid ST. It can be speculated that IL-15 production by inflammatory cells other than macrophages may occur in the rheumatoid synovium.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Arthritis, Reactive / immunology
  • Arthritis, Reactive / metabolism*
  • Arthritis, Rheumatoid / immunology
  • Arthritis, Rheumatoid / metabolism*
  • Female
  • Humans
  • Immunoenzyme Techniques
  • Interleukin-15 / metabolism*
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism
  • Macrophages / immunology
  • Macrophages / metabolism
  • Male
  • Middle Aged
  • Osteoarthritis / immunology
  • Osteoarthritis / metabolism
  • Synovial Membrane / immunology*
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism
  • Yersinia Infections / immunology
  • Yersinia Infections / metabolism
  • Yersinia enterocolitica


  • Interleukin-15