INTERLEUKIN-1-BETA, PLASMINOGEN-ACTIVATOR AND INHIBITOR OF PLASMINOGEN-ACTIVATOR IN SYNOVIAL-FLUID OF RHEUMATOID-ARTHRITIS, PSORIATIC-ARTHRITIS AND OSTEOARTHRITIS

It is generally accepted that interleukin-1 (IL-1) has a pivotal role in the evolution of joint inflammation [1]. In fact, high levels of IL -1, mostly IL-beta, are found in the synovial fluid (SF) of arthropath ies which are characterized by a strong erosive activity [2]. Many in vitro and in vivo studies have demonstrated that IL-1 stimulates a rel ease of tissue-damaging enzymes. In particular, there is evidence that IL-1 may induce the production of collagenase and stromelysin as well as the plasminogen activator (PA) that is an important stimulator of these enzymes [1]. It has been demonstrated that the urokinase PA (uPA ) is the main plasminogen activator in SF [3]. The inhibitors of PA ar e PAI-1 and PAI-2, the first being active for both tissue PA (tPA) and uPA and specific for tPA, while PAI-2 is specific for uPA. In SF the main PAI found is PAI-1 because PAI-2 can be detected only in some sev ere inflammatory conditions [4]. The aim of this study was to investig ate the relationships between IL-1 beta, uPA and PAI-1 in the SF of tw o inflammatory and one non-inflammatory arthropathies, namely RA, psor iatic arthritis (PA) and osteoarthritis (OA).