Abstract
In this study, a range of phenotypic markers were examined including membrane, cytoplasmic, and nuclear features which undergo alteration following transformation. To enable the flow cytometric analysis of these markers, a number of methods of fluorescently tagging the cells having a particular feature were examined. These included fluorescent dyes, fluorogenic substrates for enzyme markers, and fluorochromes conjugated to antibodies. Aflatoxin B[1] is known to have a considerable effect on the normal rat liver cell ploidy pattern. Flow cytometric analysis of cells and nuclei stained with a dye which intercalates into DNA, showed that the carcinogen induces division of the tetraploid population and those cells having two diploid nuclei. Three enzymes, previously reported to be associated with transformation, y-glutamyl transpeptidase, alkaline phosphatase, and guanidinobenzoatase, were studied with respect to rat hepatocarcinogenesis using fluorogenic substrates for the enzymes. On reaction with enzyme positive cells, the fluorescent products of soluble substrates appeared to become associated with the enzyme-negative cells preventing distinction of the two populations. Non-soluble fluorogenic substrates, however, allowed analysis and quantitation of those cells having the enzyme. The effect of aflatoxin B[1] on the development of cellular resistance to a number of xenobiotics was monitored, flow cytometrically, by the cells' sensitivity to adriamycin and by the relative cellular concentration of glutathione and glutathione-S-transferase. It appeared that the carcinogen has an effect on the degree of resistance to xenobiotics of all the cells in the liver, although a proportion of the cells showed a greater resistance than the main cellular population. The use of antibodies to fluorescently tag certain populations of cells was also studied. This proved to be a technically simple method of staining the cells, however the importance of having an antibody which will successfully mark all the cells having the antigen of interest was demonstrated.