Background In the pathogenesis of SLE an important place is given to immune mechanisms with many uncertain aspects. Adenosine deaminase (ADA), 5-nucleotidase (5-NT), adenosine kinase (ADK) and xanthine oxidase (XO) are the main enzymes of adenine branch of purine metabolism (PM), the activity of which is closely related to the immunological processes in the body. The role of antibodies to enzymes PM in systemic lupus erythematosus (SLE) is not defined and poorly studied.
Objectives The purpose of our work was to study antibodies to enzymes of adenine branch of PM in SLE patients and to detect correlations between studied antibodies and clinical and laboratory indices of pathological process.
Methods 30 healthy individuals aged 18 to 40 years (20 women and 10 men) and 60 SLE patients aged 22 to 58 years (55 women and 5 men) were included into the research. The diagnosis of SLE was verified using the ACR criteria of the 1997. The object of research was blood serum. IgG antibodies to ADA (anti-ADA), 5-NT (anti-5NT), ADC (anti-ADC) and XO (anti-XO) were determined in the method developed by us for indirect ELISA-assay using an immobilized form of the correlative enzyme as antigen matrix. Positive results were considered greater than 2 standard deviations of figures obtained during the examination of healthy persons (0.106 Unit for anti-ADA; 0.1 Unit for anti-5NT; 0.47 Unit for anti-ADC; 0.097 U for the anti-XO). The results were expressed as mean ± σ, differences were considered significant when p<0.05. Person correlation coefficient (r) was also used.
Results According to the results of the research the number of SLE patients with elevated levels of anti-ADA was 51.6%, anti-5NT - 41.7%, anti-ADK - 46,7%, the anti-XO - 53.3%. Comparison between the positive and negative for the presence of anti-ADA groups of patients with SLE showed a statistically significant increase in the detection rate of chronic headaches (p=0.01), lymphopenia (p=0.025) and the definition of increased values of antibodies to phospholipids (p=0.014).
Comparison between the positive and negative for the presence of blood serum anti-5NT groups of SLE patients showed an increase in the frequency of kidney damage (p=0.031) and vessels (p=0.053). Analysis of anti-5NT in relation to laboratory data allowed to identify a number of statistically significant correlations: with proteinuria (r=0,27; p=0,039), leukocyturia (r=0,35; p=0,012) and red blood cell (r=0,29; p=0,026). These data allow us to consider the anti-5NT as an additional indicator of lupus nephropathy.
Among patients with the presence of anti-ADK a significant number of patients with vascular disease (p=0,023) was revealed. A bit more often, but not statistically significant, patients with the presence of anti-ADC pulmonary injury (p=0,113) and the autonomic nervous system (p=0,124) were observed.
Comparison between the positive and negative for the presence of anti-CA groups of patients with SLE demonstrated a statistically significant increase in the frequency of signs of kidney (p=0.032) and blood vessels injury (p=0.042).
Conclusions Determination of antibodies to enzymes PM can be used as additional laboratory tests in the diagnosis of complex SLE to characterize the clinical variants of the disease.
Disclosure of Interest None declared