Elastolytic Activity of Human Monocytes from Synovial Fluid and Blood of Patients with Arthritis. Relations to Levels of Interleukin 6 and Soluble Interleukin 2 Receptor

H. S. Jensen, N. Tvede, M. Diamant, H. H. Mogensen, M. B. Hansen, B. S. Thomsen, P. B. Pedersen and K. Bendtzen. Elastolytic Activity of human monocytes from synovial fluid and blood of patients with arthritis. Relations to levels of interleukin 6 and soluble interleukin 2 receptor. Scand J Rheumatol 1991; 20: 83-90 Synovial fluid (SF) and blood from 24 patients with non-traumatic, sterile hydarthron were examined for monocyte elastolysis (M0E) and for levels of interleukin 6 (IL-6) and of soluble interleukin 2 receptor (sIL-2R). Six patients had osteoarthrosis (OA) and 18 patients had inflammatory hydarthron (IH), 10 of whom had rheumatoid arthritis (RA). Blood M0E was lower in OA than in IH, both measured as basal MøE activity and after in vitro stimulation with immune complexes and phorbol myristate acetate (PMA). SF M0E was higher than MøE in blood (p < 0.01). This increase in SF MøE could be mimicked in vitro by prestimulation of blood M0 with low levels of IC. SF IL-6 and sIL-2R were also elevated (p < 0.01). All three parameters correlated to the degree of joint inflammation evaluated by SF leucocyte level, complement activation, blood C Reactive Protein, and to the clinical evaluation of the joint. The increase in SF MøE, IL-6 and sIL-2R in patients with IH, points to a stimulation of Mø and lymphocytes in the joint. Financial support was obtained from the Danish Rheumatism Association, the Danish Medical Research Council, the Novo Foundation and the Leo Pharmaceutical Company Foundation.