An examination of the relative resistances to aflatoxin B1 and susceptibilities to γ-glutamyl p-phenylene diamine mustard of γ-glutamyl transferase negative and positive cell lines

Two epithelial cell lines have been derived from rat liver. One, containing only low levels of γglutamyl transferase (GGT) was obtained from normal liver and the other, containing high levels of the enzyme was isolated from an aflatoxin B1induced hepatoma. The GGT levels present in the two cell lines have been examined by histochemical staining, by a fluorescence assay using disrupted cells, and also by intact fluorescence-labelled cells in a laser flow cytofluori-meter. The cells containing high levels of GGT have been found to be less sensitive to microsomally-activated aflatoxin B1 than are the GGT negative cells, a feature of the in vivo situation. Evidence for activation of the γ-glutamyl derivative of an alkylating mustard analogue of p-phenylene diamine by the GGT positive cells is presented. This finding could be of relevance to the possible chemotherapy of GGT-rich lesions in vivo.