The binding properties of B6-lpr/lpr anti-DNA monoclonal antibodies were characterized to evaluate the influence of genetic background on the diversity and specificity of lpr-induced autoantibody responses. Six anti-DNA antibodies were produced from fusions with B6-lpr/lpr mice, while another was obtained from a fusion with a B6-+/+ mouse immunized with lipopolysaccharide. Each antibody bound single-stranded DNA in preference to double-stranded DNA, with variation of over 300-fold in relative binding activities. In terms of binding to a panel of synthetic polynucleotides, each antibody exhibited a unique antigenic specificity. This binding, however, was not dependent on recognition of a unique base or sugar moiety, since individual antibodies bound polymers of dissimilar composition. These results suggest a diversity of binding reactions for B6-lpr/lpr anti-DNA antibodies, with a clonal repertoire similar to that of mice from autoimmune backgrounds.