Monoclonal human anti-DNA antibodies from EB virus-transformed lymphocytes of systemic lupus erythematosus (SLE) patients.

Sixteen monoclonal human anti-DNA antibodies were obtained from Epstein-Barr virus-transformed lymphoblastoid cells of patients with systemic lupus erythematosus (SLE) and were studied in terms of antigenic specificity. All of the antibodies showed polyspecificity to polynucleotides. Among them, some antibodies had a specificity to single-stranded (ss) DNA. Especially, O-8 antibodies showed a preference for polynucleotides with pyrimidine bases. The binding specificity of the antibody was also studied using different sizes of dT oligomers in order to assess the size of the epitope. It was revealed that oligonucleotides with a size of more than 25-30 nucleotides are required for inhibition of the antibody to ss-DNA. Other studies also demonstrated that anti-ss-DNA (O-8) antibody and anti-double-stranded (ds) DNA (NE-28) antibody bound to different combining sites in the same polynucleotides, poly(dT). These results suggest that some anti-ss-DNA antibodies are directed to the conformational structure related to the base sequence and that nucleic acids, therefore, might be responsible for the possible immunogenic stimulus causing the anti-DNA immune response. We also indicate that this type of antibody would be popular among serum anti-DNA antibodies in SLE.