Cell sorter analysis of carcinogen metabolites in human tissues.

A fluorescence -activated cell sorter (FACS-II) was used to examine biochemical parameters in a heterogeneous population of cultured human lymphocytes. Incubation of cells in the presence of benz(a)anthracene (BA) during culture was employed to induce the enzyme system which metabolizes carcinogens. Carcinogen metabolism was assayed directly by measuring the phenolic metabolites of cells exposed to benzo(a)pyrene (BP). Metabolism of benzo(a)pyrene was measured in single cells and was determined to be greater in the larger cells than in the smaller cells of the cultures. For a given size of cells, the enzyme activity was greater in those exposed to benz(a)anthracene during culture. In some studies, viable cells were first sorted by size and subpopulations assayed for the o-deethylation of the compound, ethoxyresorufin, which measures more specifically the activity of cytochrome P-448. Larger cells had higher levels of enzyme activity than smaller cells in agreement with the direct determinations above. It is possible to measure carcinogen metabolism in other tissues by using the techniques described here.