Evaluation of interleukin-6 in rheumatoid arthritis as an activity criterion.

This study evaluated interleukin-6 levels as an activity criterion in rheumatoid arthritis (RA) and compared if with other activity criteria. We evaluated 35 patients with active RA, 31 with inactive RA, and 25 patients with osteoarthritis, in addition to 28 healthy individuals. Serum interleukin-6 levels were higher in active RA patients than in those with inactive RA, or osteoarthritis and healthy individuals (P < 0.001). Serum interleukin-6 levels of patients with active RA were positively correlated with the erythrocyte sedimentation rate, C-reactive protein, and alpha 2-globulin levels (P < 0.001), but there was a negative correlation with serum albumin levels (P < 0.05). We conclude that interleukin-6 can be responsible for both the most systemic manifestations of RA and for its local manifestations.