Antidouble-stranded DNA isotypes in lupus erythematosus patients with prevalent cutaneous presentation

Background: Antidouble-stranded DNA antibodies (anti-dsDNA Ab), in particular of the IgG isotype, are usually considered a marker of systemic lupus erythematosus and often correlate with the disease activity. Objectives: To determine IgG, IgA and IgM anti-dsDNA Ab in a group of 330 patients with lupus erythematosus and prevalent cutaneous lesions. Methods: The titre of anti-dsDNA Ab was determined by enzyme-linked immunosorbent assay, and disease activity was assessed by means of the systemic lupus activity measure. Results: One hundred and six patients had anti-dsDNA Ab. Thirty-nine patients had antibodies of all three isotypes of immunoglobulins, 17 had IgG + IgM, five IgG + IgA, and two IgA + IgM. Forty-three patients had a single isotype of anti-dsDNA Ab. Patients with systemic disease and higher disease activity had antibodies of all three isotypes of immunoglobulins or of IgG isotype. Remarkably, anti-dsDNA Ab of the IgA isotype, alone or associated with IgM, marked dermatological patients with low disease activity, but often with disquieting clinical and/or laboratory alterations. Conclusions: These results indicate a correlation between disease activity and both frequency and isotype of anti-dsDNA Ab.