Comparative study of tetranectin levels in serum and synovial fluid of patients with rheumatoid arthritis, seronegative spondylarthritis and osteoarthritis.

Tetranectin (TN) was assessed in paired synovial fluid (SF) and serum (S) samples from 27 patients with rheumatoid arthritis (RA), 23 with seronegative spondylarthritis (SSA) and 22 with osteoarthritis (OA). RA patients had a stronger correlation between serum and SF TN and a higher SF/S TN ratio than did SSA and OA patients. Moreover, the SF/S TN ratio exceeded 1 in most RA patients but not in SSA and OA patients, indicating the possibility of intra-articular TN synthesis in RA. A strong correlation of serum and SF TN with known inflammatory markers was observed in RA. The TN/proteinase inhibitors (PIs: alpha1-antitrypsin, alpha2-macroglobulin) molar ratio in SF was lower in RA and SSA patients to a statistically significant degree than in OA patients. In RA, in contrast to SSA and OA, this ratio correlated positively with the SF interleukin-8 (IL-8), responsible for neutrophil recruitment and degranulation, and negatively with erythrocyte sedimentation rate, serum C-reactive protein and fibrinogen, known markers of disease activity. In conclusion, patients with RA showed lower serum TN levels, a higher SF/S TN ratio and a lower SF TN/PI molar ratio than did SSA and OA patients, suggesting the implication of TN in the impaired regulation of fibrinolysis associated with the inflammatory process.