Deteriorating free radical-trapping capacity and antioxidant status in plasma during bone marrow transplantation

Organ toxicity in BMT may in part be due to free radical damage. Therefore the 'Total Radical-trapping Antioxidant Parameter of plasma' (TRAP), individual plasma antioxidants, serum iron and linoleic acid, a main substrate of lipid peroxidation, were monitored before and after BMT, and they were compared with values obtained from healthy controls. Seven patients (3 AML, 3 CML, 1 multiple myeloma) receiving 16 mg/kg busulfan, 30-45 mg VP-16 and 120mg/kg cyclophosphamide were investigated. TRAP values declined during chemotherapy by about 40% (day -9 : 1019 ± 245 μmol/l, mean ± s.d. ; day 0 : 660 ± 164 μmol/l ; P<0.05). The concentration of uric acid, one of the main antioxidants in plasma, decreased markedly (day -9 : 339 ± 108 μmol/l, day 0 : 148 ± 61 μmol/l ; P<0.05) and paralleled TRAP values. Vitamin E and bilirubin did not change from day -9 to 0 whereas vitamin C increased (day -9 : 46 ± 16 μmol/l, day 0 : 89 ± 44 μmol/l ; P<0.05). Serum iron rapidly increased within the pre-transplantation period, reaching values normally seen only in iron overload (day -9 : 11.8 ± 5.2 μmol/l, day 0 : 40.6 ± 6.5 μmol/l ; P<0.05). Linoleic acid levels were normal at the start and decreased substantially (27.0 ± 1.6 wt% at day -9 ; 15.7 ± 4.9 wt% at day 0 ; P<0.05), indicating possible lipid peroxidation during high-dose chemotherapy. In conclusion, complex monitoring of the antioxidant status before and after BMT revealed a breakdown of plasma antioxidant defence and of radical-vulnerable lipids, which was associated with high circulating levels of iron.