A pilot project in molecular cancer epidemiology: determination of benzo[a]pyrene — DNA adducts in animal and human tissues by immunoassays

Abstract

A highly-sensitive immunoassay utilizing antiserum specific for benzo[a]pyrene covalently bound to DNA has been employed to probe for adducts in the DNA of animal and human tissues and peripheral blood mononuclear cells. By enzyme-linked immunosorbent assay (ELISA) a dose-related increase in levels of benzo[a]pyrene—DNA adducts was observed in DNA from lung tissue of mice and rabbits injected i.p. with benzo[a]pyrene. Quantitation with ELISA was confirmed by i.p. injection of [ 3 H]benzo[a]pyrene and determination of adduct levels in lung DNA by radioactivity. Thus, the ELISA assay was determined to be quantitative for benzo[a]pyrene—DNA adducts in vivo , and the lower limit of detectability established at 0.08–0.10 fmol/μg DNA. At this level of sensitivity no significant differences were observed between DNA from peripheral blood mononuclear cells of dogs on smoke inhalation machines and controls. In an attempt to probe for benzo[a]pyrene—DNA adducts in human subjects resulting from chronic environmental exposure, lung tissue, lung tumor and blood samples were obtained from patients hospitalized for lung cancer and other diseases. A detailed history of exposure to environmental sources of benzo[a]pyrene and to factors known to influence polycyclic aromatic hydrocarbon metabolism was attempted for 15 patients. DNA was extracted from the lung tissue of 27 patients and blood cells of several individuals and assayed by ELISA; 5 patients appeared to have low but measurable levels of benzo[a]pyrene—DNA adducts as determined by ELISA. All of these patients were in the lung cancer group. However, the number of subjects was too small to draw conclusions relating exposure history to the occurrence of hydrocarbon—DNA adducts. These preliminary results should encourage further studies on the utilization of immunoassays for carcinogen—DNA adducts as a potential tool in epidemiological studies attempting to relate biologically-effective dose of carcinogen to human cancer risk.