Glutathione peroxidase, thioredoxin, and membrane protein changes in erythrocytes predict ribavirin-induced anemia.

ABSTRACT

OBJECTIVE: Low erythrocyte membrane protein sulfhydril concentrations are a risk factor for ribavirin-induced anemia. We further studied the role of oxidative stress and erythrocyte membrane alterations in ribavirin-induced anemia. METHODS: The levels of thioredoxin, glutathione peroxidase, protein sulfhydrils, and protein-mixed disulfides, as well as the electrophoretic membrane protein pattern, were determined in freshly isolated erythrocytes from healthy control subjects, patients without severe anemia during previous ribavirin treatment (still hepatitis C virus [HCV]-positive), and patients who had had severe anemia with ribavirin (still HCV-positive or HCV-negative), 6 months after full recovery. Erythrocytes were also incubated with buffer, ribavirin, phenylhydrazine, or dehydroepiandrosterone, and concentrations of protein sulfhydrils, protein-mixed disulfides, thiobarbituric acid-reactive substances, and total and oxidized glutathione, as well as osmotic resistance, were determined. RESULTS: Patients with previous severe ribavirin-induced anemia had lower levels of protein sulfhydrils (30.9 nmol/mg protein versus 43.2 nmol/mg protein, P<.001) and thioredoxin (0.6 nmol/g hemoglobin versus 1.2 nmol/g hemoglobin, P<.001), higher levels of protein-mixed disulfides (1.5 nmol/g hemoglobin versus 0.5 nmol/g hemoglobin, P<.001) and glutathione peroxidase (618 mU/mg protein versus 393 mU/mg protein, P<.001), and a membrane protein pattern consistent with band 4 dimer disaggregation. These differences were independent of HCV seropositivity. There were negative correlations between levels of glutathione peroxidase and thioredoxin (r=-0.87) and between levels of protein sulfhydrils and protein-mixed disulfides (r=-0.93). In vitro studies showed that erythrocytes of patients who had had hemolysis during treatment of HCV are more susceptible to oxidative stress. CONCLUSIONS: Pronounced differences in markers of oxidative stress and membrane proteins exist between patients with and without a history of ribavirin-induced anemia. Our findings suggest that there are erythrocyte-related risk factors for ribavirin-induced severe anemia.