Determination of cytokines in synovial fluids: correlation with diagnosis and histomorphological characteristics of synovial tissue.

In a study aimed at correlating cytokine levels in synovial fluid with the pathology of rheumatoid arthritis (RA), tumour necrosis factor alpha, interleukin 1 beta and interferon gamma were immunoassayed in 27 patients with RA, 16 patients with other arthritides, 23 with osteoarthritis, 13 patients with trauma, and 18 patients at necropsy without inflammatory disease and not known to have had joint disease (median 27 hours after death). The results for interleukin 1 beta clearly show higher cytokine levels in patients with RA and other arthritides than in patients with osteoarthritis, trauma, or the patients at necropsy. Interferon gamma levels in patients with osteoarthritis and the patients at necropsy, however, were significantly greater than in patients with RA, and tumour necrosis factor alpha levels were also greater in the patients at necropsy compared with patients with RA. This study also correlated histomorphological patterns of synovitis and indicators of local inflammatory activity with synovial fluid cytokine levels, showing, for example, a positive association of interleukin 1 beta titre and a negative association of interferon gamma titre with ulcerogranulomatous synovitis (itself associated with RA). Taken together, these results extend and strengthen data suggesting a possible part played by increased synovial fluid levels of interleukin 1 beta in joint destruction in RA, but provide no evidence for increases in levels of tumour necrosis factor alpha or interferon gamma affecting the disease pathology.