To clarify the significance of increased adenosine deaminase (ADA) isozyme activities in synovial fluid (SF) from patients with rheumatoid arthritis (RA).
ADA isozyme activities were measured using colorimetric assays. Concentrations of matrix metalloproteinase-9 (MMP-9) were measured by ELISA.
Levels of ADA isozyme activities in RA SF were significantly higher than those from patients with osteoarthritis and patients with traumatic injuries. Significant positive correlations between MMP-9 concentration and ADA activities were observed in RA SF (MMP-9 vs total ADA: r = 0.880; vs ADA1: r = 0.829; vs ADA2: r = 0.823; p < 0.001).
Elevated levels of ADA activities were found in SF from patients with RA. There were significant positive correlations between MMP-9 and ADA isozymes. These results may reflect the inflammatory condition of patients with RA.