Antibodies to dAT detected by membrane filtration

Sera from patients with active systemic lupus erythematosus caused the retention of the radioactively labeled synthetic polynucleotide 14C-dAT on cellulose nitrate filters. The amount of 14C-dAT bound correlated with the presence of hypocomplementemia and active renal disease. Sera containing only anti-single-stranded DNA antibodies did not bind 14C-dAT but did bind 125I DNA from E coli that had been prefiltered to remove ssDNA contamination. Inhibition experiments also indicated the presence of antigenic differences between 14C-dAT and prefiltered 125I-E coli DNA. The data suggest that dAT carries one of the major antigenic specificities for antinative DNA antibodies in SLE, and that cellulose nitrate filtration fails to remove a significant proportion of contaminating single-stranded DNA determinants in non-synthetic DNA.