RESUMO
Discoid lupus erythematosus (DLE) is a form of local inflammatory autoimmune disease limited to the skin, involving essentially the face, scalp and ear. DLE occurs in genetically predisposed individuals, sunlight being an identified trigger. Diagnosis is made by clinical examination and histopathology; laboratory tests occasionally performed include anti-nuclear antibodies titers and presence of circulating antibodies against dsDNA. DLE patients have about a 10% chance of developing systemic lupus erythematosus (SLE), a systemic inflammatory autoimmune disease affecting a range of internal organs. Although elevated titers of anti-dsDNA antibodies is an earmark for lupus disease, they are detected in only 20-55% of DLE patients by routine laboratory tests such as enzyme-linked immunosorbent assay (ELISA). In this research, we applied an electrophoretic mobility shift assay (EMSA) in parallel with an ELISA for the detection of circulating anti-dsDNA in DLE patients. The assays were conducted on sera as well as on the immunoglobulin G fraction from sera of 24 DLE patients and of 24 healthy individuals. The EMSA was positive for all DLE patients while the ELISA was positive for only 36% of them; both assays were negative for the healthy individuals. EMSA conducted on the sera of 15 patients with lichen planus was negative in all cases. Results suggest that the EMSA is more sensitive than the routine tests used for the detection of anti-dsDNA in DLE, thus helping to improve early detection of the disease and, by extension, to better evaluate the factors triggering the disease.