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Red Cell Biology & its Disorders
Ferrata Storti Foundation
Haematologica 2020 Volume 105(2):338-347
Density, heterogeneity and deformability of red cells as markers of clinical severity in hereditary spherocytosis
Rick Huisjes,1 Asya Makhro,2 Esther Llaudet-Planas,3 Laura Hertz,4 Polina Petkova-Kirova,4 Liesbeth P. Verhagen,1 Silvia Pignatelli,1 Minke A.E. Rab,1 Raymond M. Schiffelers,1 Elena Seiler,2 Wouter W. van Solinge,1 Joan-LLuis Vives Corrons,3 Lars Kaestner,4,5 Maria Mañú-Pereira,6 Anna Bogdanov2 and Richard van Wijk1
1Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands; 2Red Blood Cell Research Group, Institute of Veterinary Physiology, Vetsuisse Faculty and the Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland; 3Red Blood Cell Defects and Hematopoietic Disorders Unit, Josep Carreras Leukemia Research Institute, Badalona, Barcelona, Spain; 4Theoretical Medicine and Biosciences, Medical Faculty, Saarland University, Homburg/Saar, Germany; 5Experimental Physics, Saarland University, Saarbruecken, Germany and 6Rare Anemia Research Unit. Vall d’Hebron Research Institution, University Hospital Vall d’Hebron, Barcelona, Spain
ABSTRACT
Hereditary spherocytosis (HS) originates from defective anchoring of the cytoskeletal network to the transmembrane protein complexes of the red blood cell (RBC). Red cells in HS are characterized by mem- brane instability and reduced deformability and there is marked heterogene- ity in disease severity among patients. To unravel this variability in disease severity, we analyzed blood samples from 21 HS patients with defects in ankyrin, band 3, α-spectrin or β-spectrin using red cell indices, eosin-5- maleimide binding, microscopy, the osmotic fragility test, Percoll density gra- dients, vesiculation and ektacytometry to assess cell membrane stability, cel- lular density and deformability. Reticulocyte counts, CD71 abundance, band 4.1 a:b ratio, and glycated hemoglobin were used as markers of RBC turnover. We observed that patients with moderate/severe spherocytosis have short-living erythrocytes of low density and abnormally high intercellu- lar heterogeneity. These cells show a prominent decrease in membrane sta- bility and deformability and, as a consequence, are quickly removed from the circulation by the spleen. In contrast, in mild spherocytosis less pronounced reduction in deformability results in prolonged RBC lifespan and, hence, cells are subject to progressive loss of membrane. RBC from patients with mild spherocytosis thus become denser before they are taken up by the spleen. Based on our findings, we conclude that RBC membrane loss, cellular hetero- geneity and density are strong markers of clinical severity in spherocytosis.
Introduction
Hereditary spherocytosis (HS) is the most common form of chronic hereditary hemolytic anemia in the Caucasian population, with an estimated prevalence of 1:2000 – 1:5000.1–3 HS usually originates from mutations in ANK1 (ankyrin), SLC4A1 (band 3), SPTA1 (α-spectrin), SPTB (β-spectrin) or EPB42 (protein 4.2).1 Anemia in HS may require transfusion(s) and in severe cases splenectomy. A char- acteristic feature of HS is red blood cell (RBC) membrane instability, which leads to membrane loss and formation of dense cells with reduced RBC deformability.4–6 Increased RBC density is an important feature of HS7 and is reflected, for example, by increased mean corpuscular hemoglobin concentration (MCHC).8,9
HS is a very heterogeneous RBC disorder, resulting from a wide range of molecu- lar defects and characterized by a high degree of heterogeneity in RBC properties and disease severity.8–12 In fact, considerable differences in disease severity are reported even between HS patients with identical mutations. It therefore seems rea-
Correspondence:
RICHARD VAN WIJK
r.vanWijk@umcutrecht.nl
Received: April 3, 2018. Accepted: May 28, 2019. Pre-published: May 30, 2019.
doi:10.3324/haematol.2018.188151
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