PATTERNS OF DRUG-RESISTANCE PARAMETERS IN ADULT LEUKEMIA

P-glycoprotein (Pgp), Glutathione (GSH), Glutathione S-Transferase (GS T), and O6-Alkylguanine-DNA Alkyltransferase (ATase) were measured in parallel as putative indicators of drug resistance in adult leukemia. The patterns of resistance parameter expression of chronic and acute l eukemia were different. In acute leukemia on average all parameters we re increased as compared to normal bone marrow, In chronic leukemia GS H and GST were increased, whereas Atase, GPx and frequency of Pgp-expr ession were low. Treatment with cytostatic drugs did not influence med ian levels of expression/activity of the resistance parameters. Resist ance parameter expression/activity of leukemic cells was also compared with various other tissue and tumor types. Generally the pattern of r esistance parameter expression reflected the resistance status of the tissue, constitutively resistant tumor types and their corresponding n ormal tissue on average having higher levels than leukemic cells and o ther tissue and tumor types with acquired resistance. For individual p atients with acute leukemia, however, none of the parameters was direc tly correlated with response to treatment.