Research Report 7 describes a study that attempted to produce monoclonal antibodies to DNA adducts of nitropyrene that could be used to study the mechanism of nitropyrene-induced carcinogenesis or develop analytical techniques for monitoring exposed populations. Dr. Groopman immunized mice against nitropolycyclic aromatic hydrocarbons conjugated with a carrier protein to study the progression of immune response. Dr. Groopman injected four antigens into groups of BALB/c, AJ, and NZB mice. Two of the antigens failed to produce any immune response. While several mice developed antibodies to the other two antigens, Dr. Groopman was unable to produce stable nitropyrene-specific antibody-producing clones. Of the six New Zealand white male rabbits injected at monthly intervals with nitrosopyrene-modified keyhole limpet hemocyanin, one showed an immune response after the third injection and two showed a response after the seventh injection. The sera was then reacted with metabolites and DNA adducts of 1-nitropyrene.