A 96-well microplate ELISA for the detec-native E. coli DNA, calf thymus DNA, and tion of antibodies to DNA is described. A heat-denatured DNA. Using native E. coli number of buffers and precoating treat-DNA, virtually none of 35 normal sera had ments were used to evaluate the optimal any detectable antibody. With this antigen, method for coating the plate with DNA. as well as with native calf thymus DNA, These included pretreatment of the plates significant levels of DNA antibody were with poly-L-lysine or protamine sulfate, and found only in SLE patients. Most patients posttreatment with glutaraldehyde, none of with SLE or drug-induced lupus, as well as which improved the performance of the as-some patients with rheumatoid arthritis and say. Whereas bicarbonate and borate normal individuals had antibodies that coating buffers gave equivalent and satis-bound to heat-denatured (single-stranded) factory results, TRlS buffer resulted in very DNA. Using either native E. coli or calf high binding of immunoglobulin to wells thymus DNA, a good correlation was found not coated with antigen.
between the amount of DNA antibody de-Sera from groups of patients with autoim-tected by ELISA and the Farr-type mune disease as well as normal sera were radioimmunoassay. tested against plates optimally coated with