DNA-ANTI-DNA CIRCULATING COMPLEXES IN THE NEPHRITIS OF SYSTEMIC LUPUS-ERYTHEMATOSUS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 43  (3) , 605-614
Abstract
To determine whether circulating antigen-antibody complexes in systemic lupus erythematosus (SLE) consist of DNA and anti-DNA, cryoglobulins [CG] were isolated from the sera of 38 patients with SLE nephritis and analyzed for DNA and anti-DNA. CG were detected in 36 of the 38 sera, and DNA was found in 30 of 33 examined by either fluorescence of ethidium bromide or a radioimmunoassay. Anti-DNA activity was not detectable in any whole cryoglobulin but anti-IgG activity was found in 17. Twenty CG were treated by acid dissociation and ultracentrifugation to obtain isolated Ig; IgG was isolated from all CG and IgM from 8. Using a modified Farr assay to detect anti-ds[double-stranded]DNA and an enzyme-linked immunoadsorption assay to detect anti-ss[single-stranded]DNA, anti-dsDNA activity alone was found in 5 IgG fractions, anti-ssDNA activity alone in 5, and both anti-ds- andanti-ssDNA activity in 4. Anti-dsDNA activity was found in 3 IgM fractions. In all, anti-dsDNA activity was found in 9 of these 20 CG, and anti-DNA in 14. Analysis of these 14 CG with anti-DNA Ig fractions showed that there was enrichment of the IgG anti-DNA activity in the CG compared to the patient''s serum in all but 2 cases. In 6 of the 20 CG studied there was no detectable anti-DNA activity in isolated IgG or IgM fractions. Evidently DNA-anti-DNA complexes were present in most patients with SLE nephritis, but there was clearly a substantial minority in whom they were undetectable. In some of the latter who also had active disease the CG had anti-IgG activity. Apparently SLE can occur in the absence of DNA-anti-DNA complexes, but with other complexes present. DNA was also found in CG isolated from patients with idiopathic glomerulonephritis, but, anti-DNA activity was not detectable in Ig isolated from their CG.