Increased synovial fluid levels of interleukin-12, sCD25 and sTNF-RII/sTNF-RI ratio delineate a cytokine pattern characteristic of immune arthropathies

The assessment of cytokines and their soluble receptors in the synovial flu id (SF) of inflammatory arthropathies may be useful in studying pathogeneti c and immunoregulatory mechanisms underlying different diseases. The aim of this work was to study the cytokine network occurring in inflammatory arth ropathies and to identify a cytokine profile which is characteristic of an immune-mediated synovitis, Levels of IL-12, as well as IL-4, IL-8, IL-10, I FN-gamma, sCD25, TNF-alpha and its soluble receptors were measured in the S F of various arthropathies, i.e. non-inflammatory arthropathies: "control" meniscus pathology (n = 21), osteoarthritis (n = 22) and chronic crystal ar thritis (n = 9); a non-immune inflammatory arthropathy: acute crystal arthr itis (n = 11); 2 immune inflammatory arthropathies: reactive arthritis (ReA ) (n = 23) and rheumatoid arthritis (RA) (n = 44), SF levels of IL-10, TNF- alpha and sTNF-RII were found to be increased in the three inflammatory art hropathies compared to the "control" meniscus group. Within the inflammator y group, acute crystal arthritis was characterized by a significantly highe r sTNF-RI/TNF-alpha ratio and ReA by a significantly lower sTNF-RII/TNF-alp ha ratio compared to the two other diseases. The two immune arthropathies, RA and ReA, were characterized by increased SF levels of IL-12, sCD25 and o f the sTNF-RII/sTNF-RI ratio, ReA differed however from RA by showing lower IL-8 and IL-4 levels, higher IFN-gamma levels and a higher IL-12/IL-10 rat io, suggesting a more prevalent Th1 profile in ReA SF, Our data indicate th at the measurement of SF cytokines and soluble receptors may discriminate b etween each inflammatory arthropathy and might be useful in clinical practi ce.