Clinical and experimental evidence suggests that arachidonic acid metabolism through lipoxygenase and cyclooxygenase pathways may play an important role in the pathogenesis of both inflammatory and degenerative joint diseases. The aim of the present paper was to measure the levels of different arachidonate metabolites in arthrosis or rheumatoid joint effusions.
We studied synovial fluids from 22 patients with arthrosis and 8 patients with rheumatoid arthritis. The levels of TxB2, 6-keto-PGF1 alpha LTB4 and LTC4 were measured by radioimmunoassay.
The levels of the different arachidonate metabolites were higher in patients with rheumatoid arthritis than in those with arthrosis and the differences were always statistically significant, except for TxB2 values. Furthermore, in patients with arthrosis the levels of such metabolites were not significantly correlated with one another, with the exception of LTB4 and LTC4 values, while in patients with rheumatoid arthritis these levels were directly and significantly correlated.
In inflammatory joint disease levels of arachidonate metabolites are higher and more directly correlated with one another than in degenerative joint disease. Our data may explain the better efficacy of non-steroidal anti-inflammatory drugs in patients with arthrosis than in those with rheumatoid arthritis and the frequent necessity for steroidal treatment in this last condition.