Ifosfamide induced depletion of glutathione in human peripheral blood lymphocytes and protection by mesna

We studied the effects of ifosfamide and major metabolites on intracellular glutathione (GSH) levels in human peripheral blood lymphocytes (PBL). In vitro exposure of PBL to 4-hydroperoxylfosfamide (4-OOH-IF), acrolein or chloroacetaldehyde at 37°C for 60 min led to a concentration dependent depletion of intracellular GSH. The concentration of the three metabolites to cause a 50% depletion of GSH in PBL was in the micromolar range (acrolein: 16 ± 4 μM; 4-OOH-IF: 22 ± 9 μM; chloroacetaldehyde: 30 ± 7 μM). Exposure to ifosfamide, the non-activated drug, had no effects on the intracellular GSH levels. Pretreatment with 4-OOH-IF suppressed dose- dependently the interleukin-2-induced proliferation of PBL. Incubation of PBL together with 2-mercaptoethanesulfonate (mesna) and 4-OOH-IF, acrolein or chloroacetaldehyde prevented the GSH depletion. The protecting effect of mesna in combination with 4-OOH-IF was independent of GSH biosynthesis, because addition of buthionine sulfoximine had no significant influence on this effect. These findings indicate a novel protective mechanism of mesna against intracellular GSH depletion of PBL during exposure to metabolites of ifosfamide.