Occurrence of (E)-4-hydroxy-2-nonenal in plasma and synovial fluid of patients with rheumatoid arthritis and osteoarthritis.

(E)-4-Hydroxy-2-nonenal (HNE), a cytotoxic propagation product of lipid peroxidation, is present in the synovial fluid (0.54 (0.19) mumol/l; mean (SE), n = 9) and plasma (0.34 (0.09) mumol/l, n = 9) of patients with rheumatoid arthritis. This compound was also found in the synovial fluid (0.24 (0.19) mumol/l, n = 9) and plasma (0.09 (0.03) mumol/l, n = 9) of patients with osteoarthritis. The concentration of HNE in the plasma of patients with rheumatoid arthritis was significantly greater than in patients with osteoarthritis.