INACTIVATION OF SYNOVIAL-FLUID ALPHA-1-ANTITRYPSIN BY EXERCISE OF THEINFLAMED RHEUMATOID JOINT

Alpha1-antitrypsin (alpha1AT) is known to be oxidised by reactive oxyg en species both in vitro and in vivo, leading to its inactivation. We report here that synovial fluid (SF) alpha1AT is inactivated during ex ercise of the knee-joints of rheumatoid arthritis (RA) patients. Seque ntial SF sampling from exercised RA patients showed a marked decrease in the mean activity of alpha1AT after exercise with no change in the molecular forms of alpha1AT. No such inactivation was found in the con trol (continuously resting) RA patients. We suggest that oxidation may contribute to alpha1AT inactivation as a consequence of 'hypoxic-repe rfusion' injury after exercise of the inflamed joint.