title: Base specificity and idiotypy of anti-DNA autoantibodies reactive with synthetic nucleic acids.
abstract: Synthetic nucleic acid reactivities and the distribution of idiotypes associated with poly(dA) and poly(dT) specificities were evaluated among both monoclonal and polyclonal anti-DNA antibodies from autoimmune New Zealand mice. Ten monoclonal anti-DNA antibodies (IgG2a or IgG2b), derived from NZB/NZW mice and reactive with natural DNA (duplex and/or heat-denatured), were found to collectively exhibit a diverse binding pattern with six deoxyribohomopolymers. Several monoclonal antibodies displayed reactivity with poly(dT) comparable to that with natural DNA. Serologic studies indicated that polyclonal anti-DNA autoantibodies from NZW/NZW mice and both parental strains also cross-reacted with various homopolymers and bound preferentially with those containing pyrimidines, particularly poly(dT), relative to purines. Detailed binding analyses with two poly(dT)-reactive monoclonal antibodies demonstrated that stable DNA/anti-DNA complexes were formed with synthetic oligomers containing six to 10 nucleotides; binding to such antigens was relatively insensitive to ionic strength and inversely dependent on temperature. Both antibodies exhibited preferential binding (greater than or equal to 10-fold) with poly(dT) relative to poly(dU), suggesting the importance of the C5-methyl group and/or helical conformation in pyrimidine base recognition. Idiotypes on poly(dA)-specific and poly(dT)-specific monoclonal antibodies were found to be reciprocally distinct, localized at or near active site residues, and expressed at low levels (less than 10 to 130 ng/ml) in anti-DNA sera from all three New Zealand strains. These findings suggest that: nucleotide base determinants are significantly involved in DNA/anti-DNA interactions; poly(dT) represents a major cross-reactive synthetic antigen; and idiotype expression among lupus autoantibodies which recognize such determinants may be diverse.
mesh_terms: D000818:Animals; D000974:Antibodies, Antinuclear / Q000032:analysis* / Q000302:isolation & purification; D000911:Antibodies, Monoclonal / Q000032:analysis / Q000302:isolation & purification; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D001483:Base Sequence; D004247:DNA / Q000276:immunology*; D007130:Immunoglobulin Idiotypes / Q000032:analysis*; D051379:Mice; D008807:Mice, Inbred BALB C; D008814:Mice, Inbred NZB; D011233:Precipitin Tests; D011817:Rabbits; D011863:Radioimmunoassay
chemical_list: D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D007130:Immunoglobulin Idiotypes; D004247:DNA