Anti-dsDNA antibodies in Brazilian patients of mainly African descent with systemic lupus erythematosus: lack of association with lupus nephritis

Abstract

Renal disease is associated with morbidity and mortality in systemic lupus erythematosus (SLE) and antidsDNA antibodies with SLE immunopathogenesis. We investigated the dsDNA antibody profile of 84 Brazilian SLE patients, 27 with lupus nephritis. Thirty-six (39.1%) patients had dsDNA IgG antibodies shown in enzymelinked immunosorbent assay (454.7±281.1 WHO units/ mL), nine presenting renal disease. The following profile of dsDNA antibodies was demonstrated in Crithidia luciliae test: IgA (seven out of 36; 19.4%), IgG (22 out of 36, 66.1%); IgM (nine out of 36, 25.0%), and IgE (four out of 36, 11.1%). Two or three isotypes of dsDNA antibodies were observed in nine (25.0%) patients, while 11 (30.5%) were seronegative in the C. luciliae test. Patients with dsDNA antibodies had lower serum C3 and C4 when compared with SLE individuals without these immunoglobulins (P<0.01 and P<0.001, respectively). There was no association between any dsDNA antibody isotype and lupus kidney disease nor was anti-dsDNA IgM antibody associated with absence of nephritis.