Objective: Anti-DNA antibodies are frequently found in the serum of patients with systemic lupus erythematosus (SLE). To understand whether the avidity of SLE sera to different species of single-stranded (ss) and double-stranded (ds) DNA is different or not, the reactivity of active SLE sera to seven species of DNA from viral, bacterial, piscine, and mammalian sources was compared.
Methods: Nineteen sera from patients with active SLE were studied for their reactivity to different ssDNA and dsDNA from Escherichia coli (EC), Micrococcus lysodeikticus (ML), Clostridium perfringens (CP), calf thymus (CT), salmon testis (ST), human placenta (HP) and lambda phage by ELISA. The dsDNA was purified by treating it with S1 nuclease and proteinase K, followed by Sephacryl S-300 gel filtration. The ssDNA was purified by absorption on a hydroxyapatite column after heat-cleavage of the dsDNA.
Results: The reactivity of SLE sera to 7 species of dsDNA was not significantly different and they recognized a more widely shared epitope. In contrast, the reactivity of these sera to 7 species of ssDNA was erratic and the antigens could be grouped into high (CP and HP), medium (EC, ML, CT, and ST) and low (lambda-phage) antigenicities.
Conclusion: The anti-ssDNA and anti-dsDNA antibodies of SLE patients recognize more widely shared determinants on the DNA of seven different species. Lambda-phage DNA shows the poorest immunogenicity among them.