CHARACTERISATION OF TWO MONOCLONAL ANTIBODIES SPECIFIC FOR DIMERISED AND NON-DIMERISED ADJACENT THYMIDINES IN SINGLE STRANDED DNA*

Abstract— Hybrid cell lines (hybridomas) have been isolated from fusions between P3-NS1-1-Ag4-1 mouse myeloma cells and spleen cells from BALB/c mice hyperimmunised with UV-irradiated single-stranded DNA (UVssDNA) and UV-irradiated polydeoxythymidylic acid (UVpolydT). Monoclonal antibodies from two different hybridomas are characterised in the present report by competitive inhibition with different synthetic polynucleotides and oligonucleotides. The first antibody, designated αUVssDNA-1, recognises thymidine dimers in a polynucleotide or an oligonucleotide sequence at least four nucleotides long but not isolated thymidine dimers, suggesting that it recognises the conformational change associated with thymidine dimers. The second antibody, designated αssDNA-2, recognises unirradiated or UV-irradiated tracts of thymidine, but will not crossreact with tracts of other nucleotides (A, G, C, A.T, G.C, C.U, U). Inhibition of binding of αUVssDNA-1 to [³H]-UVssDNA by calf thymus UVssDNA is dependent on UV exposure and wavelength as expected from the antigenic determinant.