GENERATION OF KININS IN SYNOVIAL-FLUID FROM PATIENTS WITH ARTHROPATHY

An enzyme-linked immunosorbent assay method is described for the measu rement of kinin formation in synovial fluid from patients with rheumat oid and osteoarthritis (RA and GA). Basal kinin concentrations were le ss than 6 ng/ml in synovial fluid collected in the presence of inhibit ors of kinin forming (kininogenase) and kinin metabolising (kininase) enzymes. During incubation of synovial fluid in the presence of kinina se inhibitors alone, kinins were produced rapidly over the first 10 mi n, but production ceased completely within 30 min due to inhibition of the endogenous kininogenases; the rate of kinin generation during the early rapid phase correlated well with the plateau kinin concentratio n. Plateau kinin levels in synovial fluid from 15 patients with OA and RA ranged from 98 to 427 ng/ml, with a median value of 148 ng/ml. Thi s study demonstrates clearly that synovial fluid from arthritis patien ts has the capacity to produce kinins. Although the number of patients was small, the amount of kinin generated in vitro varied over a wide range and a relationship between intra-articular kinin formation and c linical features may become apparent in a larger group of patients, Th e technique could also be used to investigate other biological systems in which a role has been proposed for kinins.