Detection and quantification of 8-methoxypsoralen-DNA adducts.

8-Methoxypsoralen (8-MOP) is a photoactivated drug used clinically in the treatment of psoriasis and cutaneous T-cell lymphoma (CTCL). We have developed monoclonal antibodies which specifically recognize 8-MOP-modified DNA and do not cross-react with unmodified DNA or free 8-MOP. Highly sensitive, competitive enzyme-linked immunosorbent assays (ELISA) have been developed with both colour and fluorescence endpoint detection for quantification of DNA adducts in biological samples. In addition, immunofluorescence and flow cytometric techniques have been developed to visualize adducts in tissues and cells. These techniques have been validated in keratinocytes treated in culture and in animals treated in vivo with 8-MOP and ultraviolet A (UVA) light. Adduct levels have also been monitored in skin biopsies and lymphocytes of patients with psoriasis and lymphoma.