Evaluation of the free α-hemoglobin pool in red blood cells: a new test providing a scale of β-thalassemia severity.

Abstract

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.

• Authors: Corinne Vasseur, Serge Pissard, Elisa Domingues-Hamdi, Michael C Marden, Frédéric Galactéros, Véronique Baudin-Creuza
• Journal: American journal of hematology (Am J Hematol) Vol. 86 Issue 2 Pg. 199-202 (Feb 2011) ISSN: 1096-8652 [Electronic] United States
• PMID: 21264907 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• AHSP protein, human
• Blood Proteins
• Hemoglobins
• Molecular Chaperones
• Protein Subunits
• Recombinant Fusion Proteins
• Carbon Monoxide

Topics

• Adult
• Aged, 80 and over
• Blood Proteins (genetics, metabolism)
• Carbon Monoxide (metabolism)
• Chromatography, Affinity
• Erythrocytes (metabolism)
• Female
• Genotype
• Hemoglobins (analysis, metabolism)
• Humans
• Kinetics
• Male
• Middle Aged
• Molecular Chaperones (genetics, metabolism)
• Protein Subunits (blood, metabolism)
• Recombinant Fusion Proteins (metabolism)
• Severity of Illness Index
• Young Adult
• alpha-Thalassemia (blood, genetics, metabolism)
• beta-Thalassemia (blood, genetics, metabolism, physiopathology)