5 '-nucleotidase as a marker of both general and local inflammation in rheumatoid arthritis patients

Objectives. To evaluate measurements of serum and synovial fluid 5'-nucleot idase (5'N) activity as a marker of general and local inflammation in arthr itis, and to resolve a contradiction in the literature as to whether or not the activity of 5'N in the synovial fluids of rheumatoid arthritis (RA) pa tients is raised in comparison with that in the synovial fluids of other ar thritis patients. Methods. Assays for 5'N were carried out in the presence of inhibitors of o ther phosphatases, AMP deaminase and of 5'N itself. Results. The 5'N activity in the synovial fluid of RA patients was both sig nificantly higher (mean 1.7-fold) and had a greater variance than that in t he synovial fluids of other arthritis patients, and the contradiction in th e literature was resolved. There was a strong correlation between the 5'N a ctivity in the sera of RA patients and their erythrocyte sedimentation rate . There was no significant correlation between the 5'N in the serum and syn ovial fluid for the RA patients, in marked contrast to the strong correlati on between the two 5'N activities shown by the osteoarthritis patients. The 5'N activity was greater in the synovial fluid than in the serum for virtu ally all the patients, showing that it was being made locally. Conclusions. The 5'N activity in the serum (which came mostly from the live r) could be used as a marker of general inflammation, whereas the 5'N in th e synovial fluid was mostly produced locally, and could be used as a marker of joint inflammation, particularly for the RA patients.