CATHEPSIN-G AND ELASTASE IN SYNOVIAL-FLUID AND PERIPHERAL-BLOOD IN REACTIVE AND RHEUMATOID-ARTHRITIS

The purpose of the study was to evaluate the involvement of serine pro teinases cathepsin G and elastase on pathomechanisms in synovial fluid (SF) of patients with reactive (ReA) and rheumatoid, (RA) arthritis. Cathepsin G, elastase, and their endogenous inhibitors alpha(1)-antich ymotrypsin (alpha(1)-ACT) and alpha 1-proteinase inhibitor (alpha(1)-P I) were identified immunohistochemically from SF and peripheral blood (PB) of patients with ReA and RA. Cathepsin G and elastase activities in SF and PB were measured spectrophotometrically. Dot-immunostaining was used to identify cathepsin G,elastase, but also alpha(1)-ACT and a lpha(1)-PI from SF and PB. Cathepsin G and elastase-like activities (I U/I) were slightly elevated in ReA SF compared to the corresponding pe ripheral blood values (11.4 +/- 9.2 vs 4.8 +/- 1.7, NS, and 5.1 +/- 2. 8 vs 2.3 +/- 2.2, NS), which was similar to what was seen in RA (16.4 +/- 6.2 vs 0.53 +/- 0.4, p < 0.05, and 6.51 +/- 1.8 vs 1.22 +/- 0.58, p < 0.05). Although some samples did not contain cathepsin G and/or el astase-like activities, all samples contained immunoreactive enzyme, b ut also alpha(1)-ACT and alpha(1)-PI. In ReA SF, in contrast to monocy tes, all polymorphonuclear (PMN) cells contained cathepsin G and elast ase. Cathepsin G and elastase activities correlated,vith each other (r = 0.78, p < 0.05) suggesting PMN / primary granules as their likely s ource. There was a closer association between the cathepsin G or elast ase and SF leukocyte count in ReA than in RA. In ReA and RA SF elevate d cathepsin G and elastase activities are detected compared to activit y levels in PB suggesting local production mainly from PMNs. The co-ex istence of highly cellular SF and cathepsin G and elastase activity in the documented presence of endogenous inhibitors in ReA SF together w ith the, known, usually self-remitting clinical course of ReA, suggest a brisk and even exaggerated local PMN serine proteinase release; spa ring of joints does not seem to be due to lack or inhibition of PMN re sponses but rather to a successful down-regulation or cessation of the responses initially elicited.