In vitro effect of antibodies to DNA on the template activity of DNA.

Blood samples containing antibodies to DNA were obtained from patients with systemic lupus erythematosus (SLE) and rabbits immunized with denatured DNA complexed to methylated bovine serum albumin. The immunoglobulin fractions from these sources did not decrease the over-all template activity of singlestranded DNA with DNA polymerase or DNA-dependent RNA polymerase. In competition studies, both DNA polymerase and DNA-dependent RNA polymerase inhibited the binding of DNA antibodies to single-stranded DNA, as evidenced by inhibition of micro-complement fixation. These findings suggest that antibodies to DNA fail to decrease denatured DNA template activity because the enzymes which use a single-stranded DNA template can displace or block the antibodies from the denatured DNA as a result of greater binding affinity to the denatured DNA. The anti-DNA antibodies associated with SLE, therefore, may not be involved in the pathogenesis of the intracellular abnormalities associated with the disease.