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

Two epithelial cell lines have been derived from rat liver. One, containing only low levels of gamma-glutamyl transferase (GGT) was obtained from normal liver and the other, containing high levels of the enzyme was isolated from an aflatoxin B1-induced 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 cytofluorimeter. 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 gamma-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.