Immunological studies on DNA-lysine photoadduct.

Calf thymus native DNA was covalently linked with lysine by irradiation with 254 nm light. Thermal melting studies indicated a decrease of 16 degrees C in the Tm of DNA-lysine photoadduct over native DNA. The decrease in Tm was dependent of irradiation dose. The photoadduct was found to be a potent immunogen in experimental animal. Thymine-lysine photoconjugate in DNA-lysine photo-monoadduct appears to be the major immunodominant portion. A strong recognition of DNA-lysine photoadduct was observed with anti-DNA autoantibodies found in the sera of patients with SLE. Thymine-lysine conjugate in DNA-lysine photo-monoadduct appears to provide an immunodominant epitope(s) for SLE autoantibody recognition. The results suggests for the possible involvement of DNA-lysine photoadduct or similar modified structure(s) as a potential trigger for anti-DNA autoantibody production.