XANTHINE OXIDOREDUCTASE: ENZYME PROFILE OF PERIPHERAL BLOOD LYMPHOCYTES IN RHEUMATOID ARTHRITIS PATIENTS

The article describes the enzyme profile of xanthine oxidoreductase (XOR) of peripheral blood lymphocytes in rheumatoid arthritis patients (RA), including the activity of xanthine oxidase (XO) and xanthine dehydrogenase (XDH). The study included 77 RA patients and 35 healthy people, who made up the main and control groups, respectively. Diagnosis of RA had been established using ACR/EULAR 2010 criteria. RA activity was assessed based on the DAS28 index. Lymphocytes were isolated by A. Böyum's method using lymphosep (JCN Biomedicals) with a density gradient of 1.077-1.079 g/ml. Enzyme activity in lymphocytes was determined spectrophotometrically. XO activity was determined at a wavelength of 293 nm, and XDH at 340 nm. The enzyme activities were expressed in nmol/ min/ ml. in terms of 10 7 lymphocytes in 1 ml. The reference range (95th percentile interval) for XO activity was 14.11-31.33 nmol/min/ml; for XDH activity was 18.62-39.64 nmol/min/ml. The enzyme profile of lymphocytes in RA is characterized by a decrease in the activity of both XDH forms (XO and XDH). Analysis of the dependence of the activity of XO and XDH on the DAS28 index revealed the presence of high degree inverse correlations. The results of the study demonstrate an increase in the intensity of oxidative processes in the peripheral blood lymphocytes of RA patients.