Systemic lupus erythematosus is a systemic autoimmune disease belonging to the collagenosis group. Diagnosis of SLE is base on the 11 ACR criteria (ACR = American College of Rheumatology) . If 4 of 11 criteria are present, the probability of SLE presence is between 80 and 90%. Antibodies against dsDNA are among the most important criteria of diagnosis of SLE due to their high specificity: 70% to 98% depending on the method of detection. Since the concentration of these antibodies correlates with the disease activity, particularly with the activity of lupus nephritis, titer deteminations are suitable for monitoring therapy.