Enzyme immunoassay for IgG and IgM antibodies against dsDNA and ssDNA

Two enzyme-linked immunosorbent assays (ELISAs) for the detection of DNA antibodies are presented, one using lambda-phage DNA for the detection of dsDNA antibodies, the other using denatured calf thymus DNA for ssDNA antibodies. It was shown that only dsDNA antibodies of the IgG class were specific for SLE. IgM-dsDNA antibodies or ssDNA antibodies were not SLE-specific. Of 62 SLE patients 58% were positive for IgG-dsDNA antibodies. When only those patients with active disease were considered, 88% were positive. There was a positive correlation between the levels of IgG-dsDNA antibodies and the incidence of nephritis. When the ELISA for IgG-dsDNA antibodies was compared with the filter assay, the ELISA showed a considerably higher sensitivity.