Mutagenicity studies by co-cultivation of bronchoalveolar cells and blood lymphocytes with V79 Chinese hamster cells.
Human bronchoalveolar cells, consisting of approximately 85% pulmonary alveolar macrophages (PAMs), and peripheral blood lymphocytes isolated from healthy volunteers were investigated for their ability to metabolize 7,8-diol of benzo[a]pyrene (B(a)P). The mutagenicity of reactive metabolites was analyzed by employing a co-cultivation system using V79 Chinese hamster cells for the detection of mutations. The metabolic activity of the human cells was compared to PAMs isolated from rabbits. The number of PAMs obtained by bronchoalveolar lavage of smokers was found to be significantly elevated compared with nonsmokers. However, the mean number of induced mutations of the 7,8-diol mediated by PAMs during co-cultivation did not differ significantly between smokers and nonsmokers. The aryl hydrocarbon hydroxylase (AHH) activity of human lymphocytes has been studied by others, but to the best of our knowledge this is the first demonstration that human blood lymphocytes could be successfully used in a co-cultivation assay for the characterization of xenobiotic metabolism in terms of mutations, as illustrated by the linear increase of induced mutations in the V79 cells. Rabbit PAMs were less efficient in mediating mutations as compared to both smokers' and nonsmokers' PAMs or lymphocytes. This can probably be explained by less efficient bioactivation of 7,8-diol in rabbit PAMs, which is supported by the fact that the rabbit PAMs metabolized B(a)P in a different way as compared to human PAMs as revealed by HPLC analysis of ethyl acetate extractable metabolites of 3H-B(a)P. No qualitative or quantitative difference in the patterns of B(a)P metabolism by PAMs isolated from smokers and nonsmokers could be established. In conclusion, human PAMs were found to be more efficient in terms of cell-mediated mutagenicity than human lymphocytes, which are more efficient than rabbit PAMs. The present results differ from previous reports concerning the xenobiotic metabolizing capacity of these cells assessed by other methods. This illustrates the usefulness of the co-cultivation assay, because it measures not only the bioactivating capacity of isolated mammalian cells, but also their detoxifying capacity, the transfer of mutagens to other cells and the ability of their metabolites to cause mutations.
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000378:metabolism* / Q000494:pharmacology; D001711:Biotransformation; D002460:Cell Line; D002478:Cells, Cultured; D006224:Cricetinae; D005260:Female; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D008658:Inactivation, Metabolic; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D008297:Male; D009152:Mutagenicity Tests / Q000379:methods*; D009154:Mutation / Q000187:drug effects*; D011650:Pulmonary Alveoli / Q000166:cytology; D011817:Rabbits; D012907:Smoking
D001564:Benzo(a)pyrene; D001189:Aryl Hydrocarbon Hydroxylases; D007041:Hypoxanthine Phosphoribosyltransferase