BACKGROUND: Labile iron pool (LIP) is intracellular nonprotein bound iron that can generate oxygen radicals via the Fenton reaction resulting in oxidative cell damage. Therefore, quantitative measurement of LIP will be helpful for detecting and monitoring the toxic iron status in iron overloaded patients. This study demonstrated LIP level and its correlation to oxidative stress status in β-thalassemic erythrocytes. METHODS: LIP and reactive oxygen species (ROS) level, numbers of erythrocyte vesicles and apoptosis were assayed by flow cytometric methods in 30 blood samples from β-thalassemia/hemoglobin E patients and 17 blood samples from healthy volunteers with normal hemoglobin type. RESULTS: β-thalassemic erythrocytes showed higher LIP level, defined as the difference in calcein fluorescent intensity of the cells treated with or without deferiprone, than normal erythrocytes (mean ± 2SD as 62.39 ± 39.58 versus 44.65 ± 35.86, P = 0.003). The LIP level above 67, a cutoff value of LIP level obtained from receiver operating characteristic curve analysis, had a significant positive correlation with oxidative stress status for ROS level (r = 0.90, P < 0.001) and also the amount of erythrocyte vesicles (r = 0.79, P = 0.002). In contrast, the LIP level showed a significant negative correlation with the patients' hemoglobin level (r = -0.66, P = 0.028). CONCLUSIONS: The LIP assay is suggested as an alternative test to monitor the magnitude of iron overload and its consequent oxidative stress in β-thalassemia. LIP level may also be used as a marker for therapeutic response to iron chelation treatment.
BACKGROUND: Labile iron pool (LIP) is intracellular nonprotein bound iron that can generate oxygen radicals via the Fenton reaction resulting in oxidative cell damage. Therefore, quantitative measurement of LIP will be helpful for detecting and monitoring the toxic iron status in iron overloaded patients. This study demonstrated LIP level and its correlation to oxidative stress status in β-thalassemic erythrocytes. METHODS: LIP and reactive oxygen species (ROS) level, numbers of erythrocyte vesicles and apoptosis were assayed by flow cytometric methods in 30 blood samples from β-thalassemia/hemoglobin E patients and 17 blood samples from healthy volunteers with normal hemoglobin type. RESULTS: β-thalassemic erythrocytes showed higher LIP level, defined as the difference in calcein fluorescent intensity of the cells treated with or without deferiprone, than normal erythrocytes (mean ± 2SD as 62.39 ± 39.58 versus 44.65 ± 35.86, P = 0.003). The LIP level above 67, a cutoff value of LIP level obtained from receiver operating characteristic curve analysis, had a significant positive correlation with oxidative stress status for ROS level (r = 0.90, P < 0.001) and also the amount of erythrocyte vesicles (r = 0.79, P = 0.002). In contrast, the LIP level showed a significant negative correlation with the patients' hemoglobin level (r = -0.66, P = 0.028). CONCLUSIONS: The LIP assay is suggested as an alternative test to monitor the magnitude of iron overload and its consequent oxidative stress in β-thalassemia. LIP level may also be used as a marker for therapeutic response to iron chelation treatment.