ABSTRACT
Rheumatoid arthritis [RA] is an autoimmune connective tissue disease in which chemotaxis and excessive production of cytokines and reactive oxygen species [ROS] are characteristics of activated cytokines that play an important role in the generation of ROS in RA. Xanthine oxidase [XO] and adenosine deaminase [ADA] enzymes were reported to act as sources of ROS and advanced oxidation protein products [AOFP] was found to be a good marker of oxidative stress. To find out if XO or ADA has any role in the pathogenesis of RA; and to correlate their activities with a novel marker of oxidative stress, other cytokines, and markers of disease activities.: this study was carried out on 10 patients with RA [group I] and 10 healthy persons as a control group, [group II]. The levels of XO activity, ADA activity, AOPP, interleukin-6 [IL-6], interleukin-8 [JL-8], erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP] were estimated. XO activity, A OFF, IL-6, IL-8, ESR and CRF levels were all increased significantly in group I. Also XO and AOPP were found to have positive correlation to each other and to the acute phase reactants ESR and CRP. ADA activity showed no significant changes comparing the two studied groups. XO could be considered an important source of ROS in RA patients. XO and AOFP play at least a partial role in the pathogenesis of the disease and their levels could be used as one of the laboratory markers of the RA activity. On the other hand, ADA had no role in RA pathogenesis. It is suggested that the use of xanthine oxidase inhibitors as well as other antioxidants may be of benefit in preventing tissue damage in RA patients