To investigate the synovial fluid levels of interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), IL-1 receptor antagonist (IL-1ra), soluble IL-2 receptor (sIL-2r) and IL-8 in patients with Behçet's disease (BD) and to compare them to levels in rheumatoid arthritis (RA), and osteoarthritis (OA).
The cytokine levels of BD (n = 14), RA (n = 15) and OA (n = 15) patients were assessed by enzyme-linked immunosorbent method.
Median synovial IL-1 beta and TNF-alpha levels were higher in RA compared to BD and OA patients. IL-1 beta levels were also higher in BD than OA whereas TNF levels were similar in these two groups. IL-1ra and TGF-beta activity in BD were higher than OA but lower than RA. sIL-2r and IL-8 levels were increased in BD and RA in comparison to OA patients.
The arthritis of BD is non-erosive and accordingly, its synovial fluid contains lower levels of cytokines primarily involved in cartilage destruction, namely IL-1 beta and TNF-alpha, than RA. IL-1ra and TGF might serve as protective factors against erosion in the inflamed joints. High synovial fluid levels of sIL-2r and IL-8 probably reflect a non-specific inflammatory process.