Immunocytochemical analysis of DNA adducts in single cells: a new tool for experimental carcinogenesis, chemotherapy and molecular epidemiology

The immunocytochemical staining of carcinogen-DNA adducts by a double peroxidase-anti-peroxidase (PAP) method is critically described. It is a powerful new tool for the investigation of the initial processes of chemical carcinogenesis--such as metabolic activation of carcinogens, and modification/repair of DNA--at the level of individual, putative target cell types. It is the method of choice if the cell populations are too small for determination of adducts in isolated DNA, or if information on the tissue distribution of DNA damage is needed. Advantages of the peroxidase staining endpoint over immunofluorescence are its stability on storage of slides and the possibility of evaluation by a conventional microscope. First attempts to quantify staining intensity by microdensitometric equipment are described.