Immunological reaction of UV-induced radiation damage in coliphage DNA.

Denatured DNA of coliphage T1, poly-dT and dTpT were UV-irradiated (2537 A) and conjugated to methylated bovine serum albumin. These molecules act as haptens after injection into rabbits. Antibodies are predominantly formed against UV-induced cyclobutane-type of cis-synthymine dimers. They belong to the IgG-type of antibody molecules. Antigen-antibody complexes were detected by means of the CsCl-density gradient method. Denaturation of the DNA strongly influences the amount of specific antibodies bound to the antigen. In native DNA thymine dimers are masked concerning their reaction with antibodies. Photoproducts of UV-irradiated dTpT induce a specific production of antibody. Our results indicate that the cyclobutane type of thymine dimers is the relevant antigenic determinant group in UV-irradiated DNA.