Recognition of DNA-arginine photoadduct by anti-DNA autoantibodies in systemic lupus erythematosus.
OBJECTIVE
Studies have been carried out to synthesize and characterize the photoconjugate between positively charged amino acid, arginine and DNA fragments and their role in the induction of anti-DNA antibodies.


METHODS
Calf thymus DNA fragments of about 200 base pairs (bp) were covalently crosslinked with arginine under UV light. The amino acid was found to be covalently photoconjugated to DNA and resulted in the formation of a crosslink. The photoadduct was characterized by various physicochemical methods.


RESULTS
Photoaddition of arginine to 200 bp DNA rendered the nucleic acid conformer thermodynamically more stable than the native form. After systematic characterization of the photoadduct, it was used as an antigen for the generation of antibodies in experimental animals. The photoadducts were found to be immunogenic in rabbits, inducing high titre antibodies. The DNA-arginine photoadduct showed higher binding with SLE sera known to have high level of anti-DNA antibodies.


CONCLUSIONS
Naturally occurring anti-DNA autoantibodies were found to recognize DNA-arginine photoadduct. The recognition of DNA-arginine photoadduct by anti-DNA autoantibodies points to the role of modified DNA in the induction of anti-DNA antibodies in autoimmune disorders.
D000818:Animals; D000974:Antibodies, Antinuclear / Q000276:immunology / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism*; D001323:Autoantibodies / Q000276:immunology / Q000378:metabolism*; D018736:DNA Adducts / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008027:Light; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008239:Lysine / Q000378:metabolism; D009690:Nucleic Acid Conformation; D011817:Rabbits
D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D018736:DNA Adducts; D001120:Arginine; D008239:Lysine