A synthetic hapten for induction of thymine-dimer-specific antibodies.

High specificity and sensitivity of thymine cyclobutane dimer (thy[]thy) detection were obtained by a radioimmunoassay. Attempts to raise thy[]thy-monospecific antibodies with antigens produced according to conventional methods were unsuccessful. Thy[]thy-specific antibodies could only be raised by using a new strategy to bind thy[]thy to protein: thymine was activated by trimethylsilylation and alkylated at N1 yielding N1-thyminebutanoic acid which was dimerised by ultraviolet treatment. The resulting derivative of thymine cyclobutane dimer was coupled to bovine serum albumin by the active-ester method. The new strategy appears to be generally applicable for binding haptens, such as DNA bases, photoproducts etc, to proteins via a derivative containing a carboxyl group. Immunisation of rabbits with the thy[]thy-bovine-serum-albumin conjugate prepared by the new method resulted in a highly specific antiserum which allows detection of thy[]thy down to 0.06 p mol (15pg). The thy[]thy-specific radioimmunoassay was applied to measure thy[]thy formed in human fibroblasts which were exposed to sunlight at altitudes of 600 m or 2300 m. The amounts of thy[]thy formed in an hour corresponded to doses of 14 J m-2 and 24 J m-2, respectively, of an ultraviolet light lamp emitting predominantly 245-nm light.