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Differences in synovial fluid cytokine levels between juvenile and adult rheumatoid arthritis
F De Benedetti1, P Pignatti, V Gerloni
1Clinica Pediatrica, Istituto di Patologia Medica, Universita' degli Studi di Pavia, IRCCS Policlinico San Mateo, Italy.
Objective:
To evaluate quantitative or qualitative differences in synovial fluid (SF) cytokine levels among patients with systemic juvenile rheumatoid arthritis (JRA), antinuclear antibody positive pauciarticular JRA, or adult RA.
Methods:
SF levels of interleukin 1alpha (IL-1alpha), IL-1beta, IL-1 receptor antagonist (IL-1Ra) IL-11, tumor necrosis factor-alpha (TNF-alpha), soluble TNF receptor 1 (sTNFR1), leukemia inhibitory factor (LIF), all measured by immunoassays, and of IL-6, measured with a bioassay using B9 cells, were evaluated in 11 patients with systemic JRA, 24 with pauciarticular JRA, and 22 adult patients with RA.
Results:
SF IL-6 levels were significantly higher in patients with systemic JRA than patients with pauciarticular JRA (p = 0.003) or RA (p = 0.002). IL-1alpha was detectable in 12/24 SF samples from pauciarticular JRA, in 2/22 SF from RA, and in no sample from systemic JRA (p = 0.004 vs RA; p = 0.005 vs systemic JRA). SF IL-11 levels were significantly higher in patients with RA than patients with systemic JRA (p = 0.012) or pauciarticular JRA (p = 0.005). We found no significant differences in SF levels of IL-1beta, IL-1Ra, TNF-alpha, sTNFR1, or LIF.
Conclusion:
In systemic JRA, SF levels of IL-6 are significantly higher than in pauciarticular JRA or in RA; IL-1alpha is present in a significant proportion of patients with pauciarticular JRA, but not in those with RA or systemic JRA.