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Evaluation of the free α‐hemoglobin pool in red blood cells: A new test providing a scale of β‐thalassemia severity
Author(s) -
Vasseur Corinne,
Pissard Serge,
DominguesHamdi Elisa,
Marden Michael C.,
Galactéros Frédéric,
BaudinCreuza Véronique
Publication year - 2011
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.21918
Subject(s) - thalassemia , hemoglobin , ineffective erythropoiesis , globin , erythropoiesis , chemistry , microbiology and biotechnology , medicine , biochemistry , biology , anemia
β-Thalassemias are characterized by an imbalance of globin chains with an excess of α-chains which precipitates in erythroid precursors and red blood cells (RBCs) leading to inefficient erythropoiesis. The severity of the disease correlates with the amount of unpaired α-chains.Our goal was to develop a simple test for evaluation of the free α-hemoglobin pool present in RBC lysates. Alpha-Hemoglobin Stabilizing Protein (AHSP), the chaperone of α-Hb, was used to trap excess a-Hb. A recombinant GST-AHSP fusion protein was bound to an affinity micro-column and then incubated with hemolysates of patients. After washing, the α-Hb was quantified by spectrophotometry in the elution fraction. This assay was applied to 54 patients: 28 without apparent Hb disorder, 20 β-thalassemic and 6 α-thalassemic. The average value of free α-Hb pool was 93 ± 21 ppm (ng of free α-Hb per mg of Hb subunits)in patients without Hb disorder, while it varies from 119 to 1,756 ppm, in β-thalassemic patients and correlated with genotype. In contrast,the value of the free α-Hb pool was decreased in α-thalassemic patients (65 ± 26 ppm). This assay may help to characterize β-thalassemia phenotypes and to follow the evolution of the globin chain imbalance(α/β+γ ratio) in response to treatment.