Email updates

Keep up to date with the latest news and content from Arthritis Research & Therapy and BioMed Central.

Open Access Research article

Analysis of IL-17+ cells in facet joints of patients with spondyloarthritis suggests that the innate immune pathway might be of greater relevance than the Th17-mediated adaptive immune response

Heiner Appel1*, René Maier1, Peihua Wu12, Rebecca Scheer1, Axel Hempfing3, Ralph Kayser4, Andreas Thiel2, Andreas Radbruch2, Christoph Loddenkemper5 and Joachim Sieper12

Author Affiliations

1 Department of Gastroenterology, Infectiology and Rheumatology, Charité Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany

2 Deutsches Rheumaforschungszentrum Berlin, Schumannstrassse 21/22, D-10117 Berlin, Germany

3 Center for Spine Surgery, Werner-Wicker-Klinik, Im Kreuzfeld 4, D-34537 Bad Wildungen, Germany

4 Department of Trauma and Reconstructive Surgery, Charité Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany

5 Department of Pathology, Charité Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany

For all author emails, please log on.

Arthritis Research & Therapy 2011, 13:R95  doi:10.1186/ar3370

Published: 20 June 2011

Abstract

Introduction

In this study, we analysed the number of IL-17+ cells in facet joints, in the peripheral blood (PB) and synovial fluid (SF) of spondyloarthritis (SpA) patients and compared these results with those of patients with other rheumatic diseases and controls.

Methods

Immunohistochemical analysis of IL-17+ cells was performed in facet joints of 33 ankylosing spondylitis (AS) patients and compared with data from 20 osteoarthritis (OA) patients. The frequency of IL-17+CD4+ T cells in PB and SF of SpA patients (PB n = 30, SF n = 11), rheumatoid arthritis (RA) patients (PB n = 14, SF n = 7), OA patients (PB n = 10) and healthy controls (PB n = 12) was analysed after stimulation with Staphylococcus aureus Enterotoxin B and phorbol 12-myristate 13-acetate/ionomycin and quantified by flow cytometry.

Results

In AS facet joints, the frequency of IL-17-secreting cells was significantly higher than in samples obtained from OA patients (P < 0.001), with a slight predominance of IL-17+ cells among the mononuclear cells (61.5% ± 14.9%) compared to cells with polysegmental nuclei. Immunofluorescence microscopy revealed that the majority of IL-17+ cells were myeloperoxidase-positive (35.84 ± 13.06/high-power field (HPF) and CD15+ neutrophils (24.25 ± 10.36/HPF), while CD3+ T cells (0.51 ± 0.49/HPF) and AA-1+ mast cells (2.28 ± 1.96/HPF) were less often IL-17-positive. The frequency of IL-17+CD4+ T cells in the PB and SF of SpA patients did not differ significantly compared to RA patients, OA patients or healthy controls.

Conclusions

Our data suggest an important role for IL-17 in the inflammatory processes in AS. However, the innate immune pathway might be of greater relevance than the Th17-mediated adaptive immune response.