The effect of hydroxyl radical on the antigenicity of native DNA.
Hydroxyl free-radical mediated in vitro modification of native calf thymus DNA showed single-strand breaks, decrease in melting temperature and structural alteration of purine and pyrimidine bases. Experimentally induced antibodies against modified DNA exhibited polyspecificity. Native DNA, RNA and synthetic polynucleotides in B-conformation were found to be an effective inhibitor of induced antibody-immunogen interaction. Naturally occurring human anti-DNA autoantibodies showed enhanced recognition of modified DNA as compared to native polymer. IgG isolated from anti-DNA antibody-positive SLE sera by Protein A-Sepharose 4B chromatography were affinity purified on nDNA-(polylysyl-Sepharose 4B) matrix. In competitive binding experiments, the affinity-isolated IgG showed almost equal recognition of both native DNA and hydroxyl radical modified DNA. The possible role of hydroxyl radicals in the etiopathogenesis of SLE has been discussed.
Department of Biochemistry, Faculty of Medicine, A.M.U., Aligarh, India.
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D000818:Animals; D000906:Antibodies / Q000276:immunology; D000941:Antigens / Q000276:immunology*; D001667:Binding, Competitive; D002417:Cattle; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000737:chemistry / Q000187:drug effects / Q000276:immunology*; D004278:DNA, Superhelical / Q000187:drug effects; D006358:Hot Temperature; D006878:Hydroxides / Q000494:pharmacology*; D017665:Hydroxyl Radical; D007074:Immunoglobulin G / Q000276:immunology; D009691:Nucleic Acid Denaturation; D013056:Spectrophotometry, Ultraviolet
D000906:Antibodies; D000941:Antigens; D004278:DNA, Superhelical; D006878:Hydroxides; D007074:Immunoglobulin G; D017665:Hydroxyl Radical; D004247:DNA