Characteristics of antibody to denatured DNA in sera of patients with systemic lupus erythematosus and other rheumatic diseases.

Antibody to native (n-)DNA and denatured (d-)DNA were detected simultaneously and quantitatively in patients who had systemic lupus erythematosus (SLE) and other rheumatic diseases by the Millipore Filter method. In a group of patients who had SLE, 94% had antibody to both n-DNA and d-DNA; 6% had antibody to d-DNA only; serum that had antibody to n-DNA was not found. On the other hand, some of the patients who had progressive systemic sclerosis, dermatomyositis, polymyositis, and Sjøgren's syndrome had antibody to d-DNA only. In order to estimate the participation of anti-d-DNA antibody to lupus nephritis, patients who had SLE were classified into two groups according to immunofluorescent glomerular stainings. In a group of patients whose sera had lumpy or granular stainings, the sera reacted predominantly with n-DNA. In contrast, in the other group of patients whose sera had mesangial or linear glomerular stainings, the sera had antibodies reactive with d-DNA predominantly. These difference of reactivity between the two groups were statistically significant (P less than 0.02). The results suggest that the antibody to d-DNA is less relevant to the severity of lupus nephritis. in the evaluation of disease activity and prognosis of patients who have SLE, it will be of value to estimate the nature of anti-DNA antibodies.