Comparative characteristics of blood xanthine oxidoreductase profiles in discoid and systemic lupus erythematosus

Discoid (DLE) and systemic lupus erythematosus (SLE) are chronic inflammatory diseases of the connective tissue. Along with pathogenetic features, they have common characteristics. Immune disorders and oxidative stress are involved in pathogenesis of DLE and SLE. Development of oxidative stress is closely associated with the activation of xanthine oxidoreductase (XOR) enzyme system.Aim of the study was to reveal the features of XOR activities profiles in blood of DLE and systemic lupus erythematosus (SLE) patients.Material and methods. 31 patients with DLE, 56 patients with SLE, 35 apparently healthy individuals were enrolled in study. The activities of two convertible forms of XOR (xanthine dehydrogenase (XDG; EC 1.17.1.4) and xanthine oxidase (XO; EC 1.17.3.2)) were measured in plasma, lysed WBC and lysed RBC. The level of uric acid (UA) was determined in plasma.Results and discussion. In contrast to the control, XO activity was higher and XDG activity was lower in plasma of DLE patients; activities of both XOR forms were decreased in lysed lymphocytes. Activity of XO was lower in plasma, XO and XDG activities were higher in lysed lymphocytes in DLE regardless of the SLE activity. XDG activity in plasma of and XO activity in lysed erythrocytes DLE patients was lower than in low activity SLE, but higher than in the subgroup with moderate and high disease activity. XDG activity of lysed erythrocytes in DLE was higher than in patients with low and moderate SLE activities, but lower than in patients with high diseases activity. Uric acid content in plasma of DLE patients was not differ from the control values, its level was increased at II and III degrees of SLE activity.Conclusions. Changes in XOR activity in plasma and lysed WBC in DLE and SLE are unidirectional, but are more pronounced in the systemic form of the disease. Thus, DLE and SLE are characterized by some common changes in XOR activity, at the same time, XOR blood profiles have distinctive features, which are characteristic for nosology.