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Background: The effectiveness of red cell transfusion in a given blood unit that relied on both quantity and quality of donated cells undoubtedly affects prognostic outcomes., Objective: We aimed to determine the frequency of subclinical functional hemoglobin and red cell abnormalities in donated blood of Fayoum University Hospital in Egypt. Additionally, to assess the usefulness of reticulocyte mean hemoglobin content (RET-He) and immature reticulocyte fraction (IRF) as screening measures for such abnormalities., Material and Methods: This cross-sectional study enrolled 200 volunteer blood donors who met the national standard criterion of blood donation. Complete blood count with reticulocyte parameters, serum ferritin, sickling test, G6PD assay, Mentzer index, and naked-eye single tube red cell osmotic fragility test were carried out., Results: Functional red cell abnormalities represented 44 % of this cohort. Out of them, 4.5 % had iron deficiency, 11 % had a positive sickling test, 19 % had G6PD deficiency, and 9.5 % had suspicious thalassemia. The sensitivity and specificity test for RET-He in selective identification of functional hemoglobin abnormalities in donated blood were 83.3 % and 61.2 %, respectively at a cutoff value of 26.9. Though there was no statistically significant effect of RET-He on the selective detection of G6PD deficiency, IRF had a statistically significant high level with a p-value of 0.04., Conclusion: Subclinical functional red cell abnormalities seem to be prevalent among blood donors. Reticulocyte/ erythrocyte indices could be useful screening tools for red cell abnormalities. Further studies are required for assessing the impact of transfusing such abnormalities to neonates and other critical recipients., Competing Interests: Conflict of Interest All authors declare there is no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The mature red blood cell (RBC) lacks a nucleus and organelles characteristic of most cells, but it is elegantly structured to perform the essential function of delivering oxygen and removing carbon dioxide from all other cells while enduring the shear stress imposed by navigating small vessels and sinusoids. Over the past several decades, the efforts of biochemists, cell and molecular biologists, and hematologists have provided an appreciation of the complexity of RBC membrane structure, while studies of the RBC membrane disorders have offered valuable insights into structure-function relationships. Within the last decade, advances in genetic testing and its increased availability have made it possible to substantially build upon this foundational knowledge. Although disorders of the RBC membrane due to altered structural organization or altered transport function are heterogeneous, they often present with common clinical findings of hemolytic anemia. However, they may require substantially different management depending on the underlying pathophysiology. Accurate diagnosis is essential to avoid emergence of complications or inappropriate interventions. We propose an algorithm for laboratory evaluation of patients presenting with symptoms and signs of hemolytic anemia with a focus on RBC membrane disorders. Here, we review the genotypic and phenotypic variability of the RBC membrane disorders in order to raise the index of suspicion and highlight the need for correct and timely diagnosis., (© 2020 by The American Society of Hematology.)

Cell sickling is the process in which intracellular polymerization of deoxygenated sickle hemoglobin (HbS) leads to distorted, rigid cells, resulting in abnormal blood rheology and painful vaso-occlusion. Current methods for detection of this process mainly rely on optical microscopy of cellular morphology and measurements of cell deformability and blood rheology. As electrical impedance of cells is a sensitive indicator of changes in cellular structure and biophysical characteristics, it can be a promising marker for characterization of abnormal blood rheology and a means more convenient than optics to be integrated into point-of-care devices. In this work, a microfluidics-based electrical impedance sensor has been developed for characterizing the dynamic cell sickling-unsickling processes in sickle blood. The sensor is capable of measuring the continuous variation in the sickle cell suspension due to cyclic hypoxia-induced intracellular HbS polymerization and depolymerization. Simultaneous microscopic imaging of cell morphological change shows the reliability and repeatability of the electrical impedance-based measurements of cell sickling and unsickling processes. Strong correlation is found between the electrical impedance measurement and patients' hematological parameters such as levels of HbS and fetal hemoglobin. The combination of electrical impedance measurement and on-chip hypoxia control provides a promising method for rapid assessment of the dynamic processes of cell sickling and unsickling in patients with sickle cell disease.

Some of the most polluting activities occur in bovine skin processing. Tannery generates effluents containing high concentrations of heavy metals and organic compounds. The phases composing the leather production process generate a large volume of tannery effluents that are often discarded in aquatic environments without any previous treatment. However, the effect these xenobiotics have on adult representatives belonging to the class Amphibia remains unknown. Thus, the aim of the present study is to assess the geno- and cytotoxic effects of tannery effluent on adult male bullfrogs (Lithobates castesbeianus) exposed to it. Accordingly, the animals were divided into the following groups: negative control (tannery effluent-free water), positive control (cyclophosphamide), and effluent (water added with 5% tannery effluent). The animals were euthanized for blood collection, and erythrocyte analyses were conducted after 35 and 90 days of exposure. The micronuclei (MN) frequency and the frequency of other nuclear abnormalities in each of the animals in the experimental groups were assessed in 2000 erythrocytes. According to the present results, the exposure to tannery effluents increased MN frequency as well as other nuclear abnormalities (i.e., lobed nuclei, binucleated cell, kidney-shaped nuclei, notched nuclei, and apoptotic cell) in the erythrocytes of animals in the effluent group and in the positive control group after 35 and 90 exposure days. Thus, the current study corroborated the hypothesis that the tannery effluent has aneugenic and clastogenic potential in adult male bullfrogs (L. castesbeianus). The present study is the first to report such effect., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Sickle cell disease (SCD) is caused by an inherited mutation in hemoglobin that leads to sickle hemoglobin (HbS) polymerization and premature HbS denaturation. Previous publications have shown that HbS denaturation is followed by binding of denatured HbS (a.k.a. hemichromes) to band 3, the consequent clustering of band 3 in the plane of the erythrocyte membrane that in turn promotes binding of autologous antibodies to the clustered band 3, and removal of the antibody-coated erythrocytes from circulation. Although each step of the above process has been individually demonstrated, the fraction of band 3 that is altered by association with denatured HbS has never been determined. For this purpose, we evaluated the lateral diffusion of band 3 in normal cells, reversibly sickled cells (RSC), irreversibly sickled cells (ISC), and hemoglobin SC erythrocytes (HbSC) in order to estimate the fraction of band 3 that was diffusing more slowly due to hemichrome-induced clustering. We labeled fewer than ten band 3 molecules per intact erythrocyte with a quantum dot to avoid perturbing membrane structure and we then monitored band 3 lateral diffusion by single particle tracking. We report here that the size of the slowly diffusing population of band 3 increases in the sequence: normal cells

In carrying out their role of free radical scavenging, erythrocytes become damaged due to oxidation of membrane lipids and proteins. Such damage may change the morphology of the erythrocytes. The present study aims to demonstrate change in erythrocyte morphology in MetS and associate the changes with increased oxidative stress and inflammation that were shown in our recent study. One hundred participants were recruited from a rural town of Australia. Whole blood viscosity, erythrocyte aggregation, erythrocyte deformability, lipid profile and blood sugar level, oxidative stress markers (erythrocyte reduced glutathione, superoxide dismutase, urinary isoprostanes) and inflammatory markers (high sensitivity C-reactive protein) were measured. Erythrocyte morphological study was performed by scanning electron microscopy. Recruited participants were classified into MetS and non-MetS following the National Cholesterol Education Program Adult Treatment Panel III definition. Data were analyzed by IBM SPSS 20 software. The mean percentages of biconcave cells were decreased whereas acanthocytes, stomatocytes and echinocytes were increased in MetS group compared to healthy controls. Morphologically abnormal erythrocytes were significantly correlated with oxidative stress and chronic inflammation markers. Free radicals generated in increased concentration in MetS seem to damage erythrocyte changing its morphology which possibly could affect other hemorheological parameters., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Sickle cell disease (SCD) is a hemolytic disorder caused by a mutation in beta-globin gene and affects millions of people worldwide. Though clinical manifestations of the disease are quite heterogeneous, many of them occur due to erythrocyte sickling at reduced oxygen concentration and vascular occlusion mediated via blood cell adhesion to the vessel wall. We have followed proteomic approach to resolve the differentially regulated proteins of erythrocyte cytosol. The deregulated proteins mainly fall in the group of chaperone proteins such as heat shock protein 70, alpha hemoglobin stabilizing protein, and redox regulators such as aldehyde dehydrogenase and peroxiredoxin-2 proteoforms. Proteasomal subunits are found to be upregulated and phospho-catalase level also got altered. Severe oxidative stress inside erythrocyte is evident from the ROS analysis and Oxyblot(TM) experiments. Peroxiredoxin-2 shows significant dimerization in the SCD patients, a hallmark of oxidative stress inside erythrocytes. One interesting fact is that most of the differentially regulated proteins are also common for hemoglobinopathies such as Eβ thalassemia. These could provide important clues in understanding the pathophysiology of SCD and lead us to better patient management in the future., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Laser tweezers Raman spectroscopy was used to characterize the oxygenation response of single normal adult, sickle, and cord blood red blood cells (RBCs) to an applied mechanical force. Individual cells were subjected to different forces by varying the laser power of a single-beam optical trap, and the intensities of several oxygenation-specific Raman spectral peaks were monitored to determine the oxygenation state of the cells. For all three cell types, an increase in laser power (or mechanical force) induced a greater deoxygenation of the cell. However, sickle RBCs deoxygenated more readily than normal RBCs when subjected to the same optical forces. Conversely, cord blood RBCs were able to maintain their oxygenation better than normal RBCs. These results suggest that differences in the chemical or mechanical properties of fetal, normal, and sickle cells affect the degree to which applied mechanical forces can deoxygenate the cell. Populations of normal, sickle, and cord RBCs were identified and discriminated based on this mechanochemical phenomenon. This study demonstrates the potential application of laser tweezers Raman spectroscopy as a single-cell, label-free analytical tool to characterize the functional (e.g., mechanical deformability, oxygen binding) properties of normal and diseased RBCs., (Copyright © 2013 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

Hereditary spherocytosis (HS) is characterised by weakened vertical linkages between the membrane skeleton and the red blood cell's lipid bilayer, leading to the release of microparticles. All the reference tests suffer from specific limitations. The aim of this study was to develop easy to use diagnostic tool for screening of hereditary spherocytosis based on routinely acquired haematological parameters like percentage of microcytes, percentage of hypochromic cells, reticulocyte counts, and percentage of immature reticulocytes. The levels of haemoglobin, mean cell volume, mean corpuscular haemoglobin concentration, reticulocytes (Ret), immature reticulocytes fraction (IRF), hypochromic erythrocytes (Hypo-He) and microcytic erythrocytes (MicroR) were determined on EDTA samples on Sysmex instruments from a cohort of 45 confirmed SH. The HS group was then compared with haemolytical disorders, microcytic anaemia, healthy individuals and routine samples (n = 1,488). HS is characterised by a high Ret count without an equally elevated IRF. All 45 HS have Ret >80,000/μl and Ret(10(9)/L)/IRF (%) greater than 7.7 (rule 1). Trait and mild HS had a Ret/IRF ratio greater than 19. Moderate and severe HS had increased MicroR and MicroR/Hypo-He (rule 2). Combination of both rules gave predictive positive value and negative predictive value of respectively 75% and 100% (n=1,488), which is much greater than single parameters or existing rules. This simple and fast diagnostic method could be used as an excellent screening tool for HS. It is also valid for mild HS, neonates and ABO incompatibilities and overcomes the lack of sensitivity of electrophoresis in ankyrin deficiencies.

Aristotelia chilensis (Mol.) Stuntz (A. chilensis), also known as maqui, is a plant of the Elaeocarpaceae family that grows in central and southern Chile as well as southwestern Argentina. Infusions of its leaves have long been used in the traditional native herbal medicine to treat different ailments. Phytochemical studies of the plant's chemical composition of the plant indicate the presence of indolic alkaloids, flavonoids, cianidine glucosides, delfidine, malvidine, petunidine, cumarines and triterpenes. These compounds, particularly the flavonoids, have antioxidant properties. In order to evaluate the mechanisms of its toxicity and their antioxidant properties, the leaves' aqueous extracts were induced to interact with human red cells, their isolated unsealed membranes (IUM), and molecular models of the human erythrocyte membrane. These consisted of multibilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipids classes located in the outer and inner monolayers of the human erythrocyte membrane, and large unilamellar vesicles (LUV) of DMPC. The capacity of A. chilensis aqueous extracts to perturb the bilayer structure of DMPC and DMPE was evaluated by X-ray diffraction, DMPC LUV and IUM were studied by fluorescence spectroscopy, and intact human erythrocytes were observed by scanning electron microscopy (SEM). Results of the present study indicate that aqueous extracts of A. chilensis induced an alteration of human erythrocyte morphology from the normal discoid shape to an echinocytic form, changes that are explained in terms of the extract interaction with the membrane's outer phospholipid monolayer.

Constitutional deficit in the erythroid protein 4.1 (4.1R), a structural component of the erythrocyte membrane, is implicated in hereditary elliptocytosis. Acquired deficit in protein 4.1R have been rarely described in myelodysplastic syndromes. Here, we report a series of six patients presenting a myelodysplastic or a myeloproliferative disease in association with an elliptocytosis curve on osmotic gradient ektacytometry and a significant decrease in protein 4.1R level. We confirm that deficit in protein 4.1R is recurrent in myeloid malignancies and should be particularly investigated when deletion del (20 q) is present, since we found this chromosomal abnormality in four out of six patients., ((c) 2007 Wiley-Liss, Inc.)

Background: % Microcytic and % hypochromic red cells show an inverse trend in beta thalassemia trait and in iron deficiency anemia (IDA). The aim of this study was to assess the discriminant value of % microcytic/% hypochromic ratio, as can be obtained from the Advia 2120 (Siemens) analyzer, in the differential diagnosis of microcytic anemia, compared to the conventional England and Fraser, Green and King, Mentzer, Ricerca, Shine and Lal and Srivastava indices., Methods: Receiver operating characteristic (ROC) curves, sensitivity, specificity and Youden index of indices were calculated for a set of 148 IDA patients and 170 beta thalassemia carriers., Results: The Green and King index showed the best area under the curve (AUC, 0.962), with a Youden index of 80.9%; the % microcytic/% hypochromic ratio ranked second (AUC 0.943), with a Youden index of 76.3% and a sensitivity of 99.2%., Conclusions: This index, with high sensitivity for beta thalassemia screening, can be a useful tool in the differential diagnosis of microcytic anemia, so samples can be chosen for HbA(2) analysis, to confirm the presumptive diagnosis of the disease. As specificity is 77.1%, we assume it will be 22.9% for false positives, but these samples will have HbA(2) values within the reference range, for correct diagnosis.

This 22-year-old women presented to the ante-natal clinic of this hospital for prenatal screening for beta-thalassemia. Cation exchange high performance liquid chromatography (HPLC) using 'Beta Thalassemia Short Program' on Bio-Rad 'Variant' system revealed HbC value of 81.6%. The CBC showed microcytic hypochromic anemia. The HPLC and CBC suggested the possibility of compound heterozygote state for HbC/beta-thalassemia. The alkali and acid electrophoresis findings were consistent with the above diagnosis. The DNA analysis confirmed compound heterozygote state for HbC/beta(0)-thalassemia (Fr 8/9 mutation). The studies on the parents showed that mother was a compound heterozygote for HbD(Punjab) and HbC while father had beta-thalassemia trait. To the best of our knowledge, this is the first confirmed report of HbC from India. The paper discusses the hematological findings in this subject and her mother (a compound heterozygote for HbD(Punjab) and HbC).

A proteomic approach using a cleavable ICAT reagent and nano-LC ESI tandem mass spectrometry was used to perform protein profiling of core RBC membrane skeleton proteins between sickle cell patients (SS) and controls (AA), and determine the efficacy of this technology. The data was validated through Peptide/Protein Prophet and protein ratios were calculated through ASAPratio. Through an ANOVA test, it was determined that there is no significant difference in the mean ratios from control populations (AA1/AA2) and sickle cell versus control populations (AA/SS). The mean ratios were not significantly different from 1.0 in either comparison for the core skeleton proteins (alpha spectrin, beta spectrin, band 4.1 and actin). On the natural-log scale, the variation (standard deviation) of the method was determined to be 14.1% and the variation contributed by the samples was 13.8% which together give a total variation of 19.7% in the ratios.

Lactate and H(+) are suggested to promote the sickling process in red blood cells (RBCs) containing hemoglobin S. We demonstrated greater activity of the RBC monocarboxylate cotransporter MCT-1, lower RBC deformability and impaired hematological indices in sickle cell trait (SCT) carriers compared to control subjects, suggesting an involvement of MCT-1 in hemorheological disturbances in SCT carriers.

Disorders of the red blood cell membrane, such as hereditary spherocytosis, hereditary elliptocytosis, and hereditary pyropoikilocytosis, are characterized by heterogeneity in their clinical and laboratory manifestations. Advances in molecular biology have allowed determination of the precise genetic defect in many cases of membrane-associated anemia and have revealed significant genetic heterogeneity. Six genetic loci have been identified and many defects, including gene deletions and insertions, missense and nonsense mutations, and splicing mutations, have been found. Analysis of these defects has provided a better understanding of the pathogenesis of these disorders and allowed a better understanding of the structure/function relationships of the proteins of the erythrocyte membrane.

The present molecular-level understanding of polymerization and sickling is reviewed for 2 central questions in sickle hemoglobin pathophysiology, viz., what determines when cells sickle, and what determines when cells get stuck. The description of sickling includes the central aspects of the double nucleation mechanism, as well as recent results on the effects of crowding, with an emphasis on the physiological applicability of this fundamental knowledge. In considering when cells get stuck, new measurements of individual fiber stiffness and the processes of depolymerization are also considered. Finally, a fundamental connection is shown between thermodynamics and rheology.

The extent to which dense and irreversible sickle cells (ISCs) contribute to vaso-occlusive episodes in sickle cell disease remains unclear. N-Acetylcysteine (NAC) inhibits dense cell and ISC formation in sickle erythrocytes in vitro and restores glutathione levels toward normal. A phase II double-blind randomized clinical trial was completed to determine the efficacy of NAC in decreasing dense cell and ISC formation, and vaso-occlusive episodes in sickle cell disease. Twenty-one subjects with a history of at least two vaso-occlusive episodes per year and 6% dense cells were enrolled. Four treatment groups were analyzed; NAC at a dose of 2,400 mg per day decreased the percent dense cells from 20.1 +/- 2.9 to 12.6 +/- 2.1 (P < 0.05) and increased red cell glutathione levels from 292.8 +/- 74.5 to 576.7 +/- 155.1 (P < 0.05). In addition, we observed a decrease in vaso-occlusive episodes from 0.03 to 0.006 episodes per person-days and a decreased in relative risk to R = 0.39. Although NAC did not significantly decrease the number of ISCs, there was a downward trend at all doses tested. In summary, NAC inhibited dense cell formation, restored glutathione levels toward normal, and decreased vaso-occlusive episodes at a well-tolerated dose of 2,400 mg per day. To determine the long-term efficacy and safety of NAC, a multicenter phase III clinical trial is required., (Copyright 2003 Wiley-Liss, Inc.)

Although selection of hemoglobin C (HbC) by malaria has been speculated for decades, only recently have epidemiologic studies provided support for HbC protection against malaria in West Africa. A reduced risk of malaria associated with the homozygous CC state has been attributed to the inability of CC cells to support parasite multiplication in vitro. However, there have been conflicting data and conclusions regarding the ability of CC red cells to support parasite replication. Reports that parasites cannot multiply in CC cells in vitro contrast with detection of substantial parasite densities in CC patients with malaria. We have therefore investigated Plasmodium falciparum growth in CC cells in vitro. Our data show that the multiplication rate of several P falciparum lines is measurable in CC cells, but lower than that in AA (HbA-normal) cells. A high proportion of ring forms and trophozoites disintegrates within a subset of CC cells, an observation that accounts for the overall lower replication rate. In addition, knobs present on the surface of infected CC cells are fewer in number and morphologically aberrant when compared with those on AA cells. Events in malaria pathogenesis that involve remodeling of the erythrocyte surface and the display of parasite antigens may be affected by these knob abnormalities. Our data suggest that only a subset of CC cells supports normal parasite replication and that components of malaria protection associated with the CC state may affect the parasite's replication capacity and involve aberrant knob formation on CC cells.

The aim of this study was to explore the relationship between local ischaemic preconditioning and the effectiveness of fractionated radiotherapy. The rat serum, bone marrow, and small intestine were examined for oxidative changes induced by total body irradiation with gamma rays with applied local ischaemic preconditioning immediately before irradiation. Serum concentrations of TBA-RS examined 12 hours after the last irradiation did not reveal any differences among the groups of animals analyzed. Twenty-four hours after the last dose of irradiation, the serum concentrations of TBA-RS varied in particular groups (P<0.0001). The concentration of triglycerides in the serum of local preconditioned ischaemia and irradiated animals showed a reversed shape similar to the TBA-RS fluctuation (P<0.003). The level of uric acid in the serum of animals treated only with radiation is slightly higher than the level of this acid in the serum of the local preconditioned ischaemia radiation group (P<0.58). The number of bone marrow polychromatic erythrocytes did not appear to differ substantially in both irradiated groups. At the first 12 hours after irradiation, the frequency of micronucleated polychromatic erythrocytes is significantly different in the bone marrow of both groups either in combination with ischaemic preconditioned radiation or with radiation alone (P<0.0002). In irradiated animals without ischaemic preconditioning, on the 3rd day after irradiation the number of crypts increased and in the next days decreased achieving the level of the control group on the 7th day. Irradiated rats with local ischaemic preconditioning did not reveal an increase in the number of crypts. The difference was statistically significant (P<0.05). These data indicate that the local ischaemic preconditioning modifies the radiation peroxidising effects through inhibition of free radical-dependent lipid peroxidation and, probably, other unrecognized mechanisms., (Copyright 2003 Wiley-Liss, Inc.)

We present the characterization of the molecular spectrum and frequency data of alpha-thal (thal) defects in Tunisia, and an evaluation of the efficacy and limitations of Hb Bart's (gamma4) measurement for the screening of alpha-thal at birth. Cord blood samples were collected from two different areas: the northeast of the country, an area where Hb H (beta4) disease frequently occurs, and Tunis, the capital city, representative of the average Tunisian population. From the first group, 110 samples with Hb Bart's and/or microcytosis at birth were selected from 1270 randomly collected samples. Two additional population samples, one from the same northeastern region (n = 90), the other from Tunis (n = 104) were collected randomly. Nine common deletional alpha-thal defects and nondeletional mutations were screened. In the northeastern samples, selected for the presence of Hb Bart's and microcytosis, the -alpha3.7 deletion was the most common defect (4.5% allele frequency) followed by a polyadenylation (poly A) signal mutation (1.8%), the five nucleotide (nt) deletion and the -alpha4.2 deletion (both 0.9%). The African polymorphism (G-->TCGGCCC at position 7238 and T-->G at 7174) was found with an allele frequency of 11% in the selected northeastern samples. In the random population samples, the overall alpha-thal allele frequency was 4% in the northeast region, against 2% in the average Tunisian population. The +14 (G-->C) polymorphism in the 5'UTR (untranslated region) of the alpha2 gene and the African polymorphism in the second intron of the same gene, were found in 3.5% of the alleles. No alpha0-thal alleles were found among the 304 blood samples studied at the DNA level during this survey.

Peripheral red blood cells obtained from 227 urological patients with chronic renal failure and purulent intoxication (78 of them were treated by hemodialysis and hemosorption) are examined. Scanning electron microscopy, cell surface charge, lipid peroxidation in erythrocytes, blood viscosity data are summarized. Significant morphofunctional changes dependent on the severity of the intoxication and the detoxication efficiency are manifestation of nonspecific features of the cell injury and adaptation. Their complex and dynamics are suggested as important diagnostic criteria.

Lecithin:cholesterol acyltrasferase (LCAT) plays a key role in the cholesterol metabolism-mediated esterification of free cholesterol into the cholesterol ester in normal plasma. Familial LCAT deficiency is frequently associated with anemia. Using biochemical and physiological techniques, the erythrocytes of this patient were investigated to gain an insight into the relationship between the abnormalities of lipid metabolism and erythrocyte membrane fragility. Abnormal erythrocytes, so-called Target cells and/or Knizocytes, were observed at 20% in our patient's erythrocytes. Moreover, the mean corpuscular volume of the patient's cells was 7% greater than that of a normal individual. In the membrane lipids of the patient's erythrocytes, cholesterol and phosphatidylcholine increased, and phosphatidylethanolamine decreased. The electron spin resonance technique with a fatty acid spin probe showed that the membrane fluidity was more elevated than that of normal cells in spite of the increase in cholesterol content and the cholesterol/phospholipid ratio of the membrane of patient's erythrocytes. The patient's abnormally shaped erythrocytes were less deformed than those of the normal individual under high shear stress. The partial depletion of membrane cholesterol from the patient's erythrocytes was demonstrated by incubation with normal plasma with LCAT activity. The increment of transformed erythrocytes during the incubation could be prevented by cholesterol depletion from the patient's erythrocyte membrane. These findings indicate that normochromic anemia of the patient might be caused by erythrocyte fragility resulting from decreased deformity and/or abnormal shape of the cells due to abnormal lipid composition in the membrane.

Key antioxidant defense reactions in RBCs are linked to nicotinamide adenine dinucleotide (NAD(+)) and nicotinamide adenine dinucleotide phosphate (NADP(+)). The ratio of reduced (NAD(P)H) to total pyridine nucleotide pool [(NAD(P)(T) i.e. NAD(P)H plus NAD(P)(+)], which is known as redox potential, reflects the redox status of erythrocytes. Through the utilization of a spectrophotometric cycling assay, the NAD(+) and NADP(+) redox potentials were determined in erythrocytes from normal Saudi subjects and those with sickle cell disease (SCD). The sickle erythrocytes NADH/NAD(T) ratio (0.386) was reduced compared to the normal ratio (0.464). This reduction appears to be due to a significant increase in oxidized NAD(+) in sickle RBCs. However, the value of the redox potential of erythrocytes in Saudi subjects with SCD is slightly higher than that reported for comparable African Americans. Although the high fetal hemoglobin is the main factor in the amelioration of the clinical course exhibited by Saudi sickle cell patients, it is assumed that the slight improvement in the redox potential may play a part in this process. This is supported by a relatively uninhibited glycolytic pathway in the erythrocytes of Saudi subjects with SCD with a higher level of NADH than their African American counterparts., (Copyright 2002 S. Karger AG, Basel)

Although most of the diagnostic applications of flow cytometry bring forth examples of leukocyte immunophenotyping for immunodeficiency diseases and leukemia-lymphoma diagnosis, the same technology has improved medical assessment of diseases affecting the red cell and erythropoiesis. Flow cytometric methods were first applied to laboratory hematology with the improvement in reticulocyte counting and the creation of the immature reticulocyte fraction for better anemia evaluation and therapeutic monitoring. A more recent improvement attributable to flow cytometry is accurate detection of fetal red cells in the evaluation of FMH hemorrhage. The same method used in the detection of fetal RBCs based on HbF content measurement using monoclonal antibodies also offers the potential for enumeration of F cells, which promises to have use in therapeutic monitoring of patients with sickle cell disease and the evaluation of other hemoglobinopathies and myelodysplasia. Other clinical uses of flow cytometric RBC analysis include nonisotopic red cell survival studies, sensitive blood group typing, sensitive detection of immune-mediated hemolytic diseases, and evaluation of parasitic diseases whose life cycle involves intracellular RBC infestation. This article summarizes red cell flow cytometry, particularly as it impacts the areas of immunohematology and laboratory hematology, and points to areas of potential future contribution of this technology to diagnostic medicine.

Lipid rafts are sphingolipid- and cholesterol-rich membrane microdomains that are insoluble in nonionic detergents, have a low buoyant density, and preferentially contain lipid-modified proteins, like glycosyl phosphatidylinositol (GPI)-anchored proteins. The lipid rafts were isolated from human erythrocytes and major protein components were identified. Apart from the GPI-anchored proteins, the most abundant integral proteins were found to be the distantly related membrane proteins stomatin (band 7.2b), flotillin-1, and flotillin-2. Flotillins, already described as lipid raft components in neurons and caveolae-associated proteins in A498 kidney cells, have not been recognized as red cell components yet. In addition, it was shown that the major cytoskeletal proteins, spectrin, actin, band 4.1, and band 4.2, are partly associated with the lipid rafts. Stomatin and the flotillins are present as independently organized high-order oligomers, suggesting that these complexes act as separate scaffolding components at the cytoplasmic face of erythrocyte lipid rafts.

One of the pathogenetic mechanisms responsible for sickling of erythrocytes in patients with sickle cell disease is the decreased hydration status of the cells. In this brief review, we discuss the pathophysiologic background and explore some new treatment options to prevent vaso-occlusive crises or other problems in this patient population.

The occurrence of the mutant hemoglobin Hb S in human red blood cells results in sickle cell anemia. This disease, including its genetic and molecular bases, has been extensively investigated and is well understood (1,2). The presence of deoxy-induced sickling of animal erythrocytes is largely unknown, however. We examined red blood cells (RBCs) from several fish species in vitro under aerated and anoxic conditions. Our polarized light microscopic techniques were aimed at establishing correlations between erythrocyte morphology, state of oxygenation, spectral absorbance, linear dichroism, and linear birefringence. We found no fish with intracellular HbO2 polymerization; but there were intraerythrocytic aggregations of deoxy Hb with a high degree of either molecular order or disorder. The ordered aggregates in the RBCs of Atlantic cod, haddock, and toadfish were remarkably similar in dichroic ratio magnitudes and birefrigence to those in human RBCs that contain HbS. Therefore, fish hemoglobins appear to be good models of sickling disorders and polymerization-related phenomena. The consequences of sickling on animal health and fish aquaculture remain to be studied.

Lipid phase transformations may occur in the membranes of sickle red cell shed-vesicles and sickle red cells. The presence of such phase changes could be important in sickle cell disease since membrane phase changes appear to contribute to the generation of antiphospholipid antibodies that are thrombophilic and occur in sickle cell disease. In the present study, we have evaluated sickle red cell shed-vesicles and sickle red cells for the presence of non-bilayer lipid phases using 31P-NMR spectroscopy. Results show that the spectra of both the shed-vesicles and the sickle red cells are compatible with the occurrence of non-bilayer phases in the membrane bilayers. The findings support the concept that these membranes could contribute to the generation of antiphospholipid antibodies in sickle cell disease.

We have identified a rabbit autoantibody that strongly reacts with the core membrane skeleton of control red blood cells, and does not react with low- or high-density sickle cell core skeletons upon indirect immunofluorescence. Western blot analysis of red blood cell membrane proteins, utilizing this autoantibody, indicated no reactivity to any protein when SDS-PAGE was conducted in the presence of the reducing agent, dithiothreitol. However when SDS-PAGE was performed on control red blood cell membrane proteins separated in the absence of dithiothreitol, the autoantibody specifically reacted with a high molecular weight polypeptide (apparent Mr approximately equal to 310 kD) representing a DTT sensitive form of control alpha spectrin, which we refer to as alpha' spectrin. There was no staining of high density or low density sickle cell alpha or alpha' spectrin. This autoantibody should be an excellent tool for the fine mapping of structural change(s) in control vs. sickle cell alpha spectrin, and determination of whether the structural alteration effects spectrin dimer-tetramer interconversion and/or the spectrin-actin interaction. The modification in alpha spectrin, detected by this antibody, is very specific for homozygous SS alpha spectrin because sickle cell beta+ thalassemic alpha spectrin and sickle cell trait alpha spectrin react intensely with the autoantibody.

Background and Objective: Reduced serum or erythrocyte Mg have been reported in human beta thalassemia. These deficiencies may play a role in the cellular abnormalities characteristic of this disorder. We have therefore studied the effect of dietary Mg supplementation in patients with beta thalassemia intermedia in order to establish whether it improves the abnormalities of thalassemic erythrocytes., Design and Methods: Plasma and erythrocyte Mg were determined in 11 patients with b thalassemia intermedia, not requiring chronic transfusion therapy, and in 17 normal controls. Inclusion criteria included normal renal and liver function and performance status of 70% or greater. Seven patients were enrolled for the Mg supplementation study, after the appropriate informed consent was obtained. They were given a starting dose of 0.6 mEq/kg/day of magnesium pidolate, divided into two oral daily doses, for four weeks. In a 70-kg subject, a daily Mg dose of 42 mEq corresponds to 504 mg of Mg, with the daily Mg intake of normal subjects being 418 +/- 120 mg for males and 343 +/- 94 mg for females. After 28 days of treatment, five of the patients continued the protocol with a daily dosage increased to 1.2 mEq magnesium pidolate/kg/day, divided into two oral administrations, for an additional four weeks., Results: In patients with untransfused beta thalassemia intermedia we found reduced erythrocyte Mg (in mmol/kg Hb, 6.12 +/- 1.5, n = 11 vs. 8.69 +/- 0.89, n = 17, respectively, p < 0.0001) and normal serum Mg. In the seven patients given oral Mg supplements, at Mg dosages of 0.6 mEq/kg/day we observed significant increases in erythrocyte Mg, and significant improvement in some of the characteristic abnormalities of beta that erythrocytes (increased Na-K pump, KCl cotransport, cell dehydration, increased osmotic resistance). These changes were maintained in the 5 patients who were treated with 1.2 mEq of Mg/kg/day. Follow-up studies showed a return to baseline conditions. There were no signs of Mg toxicity, with the only side effect being diarrhea, which was generally mild, but led to discontinuation for one patient after the first four weeks., Interpretation and Conclusions: These data indicate that dietary Mg supplementation improves some of the characteristic cellular function abnormalities of b thalassemia intermedia. The possible therapeutic value of this strategy should be further tested in these patients.

By its frequency, but also by its morbidity and mortality, sickle cell disease is a real problem of public health in Senegal. It is an inherited disease of the red blood cell, characterized by vaso-occlusive manifestations in several organs, and chronic hemolytic anemia. Out of this work carried upon subjects presenting sickle cell trait (AS), we especially studied the membrane phospholipids. The aims of this study was to identify and to measure the major phospholipids of the red blood cell membrane (lecithin, lysolecithin, cephalin, lysocephalin and sphingomyelin). We noted a significant decrease of the lecithine rates, associated with significant accumulation of lysophosphatidyl choline implied in hemolysis disorders. We have also noted a significant increase of sphingomyelin which might be involved in the adhesive phenomena of the sickle cells. These preliminary results, allow to consider eventual new therapeutics, at least to reduce the clinical disorders of this painful disease.

Phenolphthalein, a common ingredient in nonprescription laxatives and a multisex, multispecies rodent carcinogen, was evaluated under chronic exposure conditions for genotoxicity in transgenic female mice heterozygous for the p53 gene (heterozygous TSG-p53 mice). Phenolphthalein was administered in the diet at 200, 375, 750, 3,000, and 12,000 ppm (corresponding to a time-weighted average of 37, 71, 146, 569, and 2,074 mg/kg/day, respectively) for 6 months (183 days). On days 39, 92, 137, and 183 of treatment, peripheral blood samples were collected and evaluated for the frequency of micronucleated polychromatic and normochromatic erythrocytes (MN-PCE and MN-NCE, respectively), the percentage of PCE (%PCE) among total erythrocytes, and the extent of DNA damage (single strand breaks, alkali labile sites, DNA crosslinking) in leukocytes. In addition, the extent of DNA damage was evaluated in liver parenchymal cells sampled from mice at the end of the 6-month treatment period. DNA damage was evaluated using the alkaline (pH > 13) Single Cell Gel (SCG) assay. In addition, using a modified SCG technique, the frequencies of leukocytes and liver parenchymal cells with extremely low molecular weight DNA (indicative of apoptosis and/or necrosis) were determined. At each sample time, phenolphthalein induced a highly significant, dose-dependent increase in the frequency of MN-PCE and MN-NCE and in %PCE. Maximal induction of MN-PCE and %PCE decreased with increasing treatment duration, most likely due to a treatment duration-dependent decrease in the relative amount of ingested phenolphthalein. A comparative analysis of the kinetochore status of MN in erythrocytes sampled from control mice and mice ingesting phenolphthalein at 12,000 ppm for 183 days indicates that the induced MN resulted predominantly but not exclusively from numerical chromosomal damage. The analysis for increased levels of DNA damage in blood leukocytes was inconclusive, with a small but statistically significant increase in DNA migration on days 39 and 137 but not on days 92 and 183. The extent of DNA migration in liver parenchymal cells sampled from mice at the end of treatment was not altered significantly. The frequencies of apoptotic and/or necrotic leukocytes and liver parenchymal cells were not increased among mice ingesting phenolphthalein. The lowest effective dose at which a significant genotoxic response (i.e., the induction of MN-NCE) was detected was 200 ppm, the lowest dose tested in this study. This dose in mice is comparable to doses (on a mg/m2 basis) experienced by humans.

Intracellular polymerization and sickling depend markedly on the cellular concentration of sickle hemoglobin (Hb S). A possible therapeutic strategy for sickle cell disease is based on reducing the cellular concentration of Hb S through prevention of erythrocyte dehydration. The K-Cl cotransporter is a major determinant of sickle cell dehydration and is inhibited by increasing erythrocyte Mg content. We studied 10 patients with sickle cell disease before treatment and after 2 and 4 wk of treatment with oral Mg supplements (0.6 meq/kg/d Mg pidolate). Hematological parameters, erythrocyte Na, K, and Mg content, erythrocyte density, membrane transport of Na and K, and osmotic gradient ektacytometry were measured. We found significant increases in sickle erythrocyte Mg and K content and reduction in the number of dense sickle erythrocytes. Erythrocyte K-Cl cotransport was reduced significantly. We also observed a significant reduction in the absolute reticulocyte count and in the number of immature reticulocytes. Ektacytometric analysis showed changes indicative of improved hydration of the erythrocytes. There were no laboratory or clinical signs of hypermagnesemia. Mild, transient diarrhea was the only reported side effect. We conclude that oral Mg supplementation reduces the number of dense erythrocytes and improves the erythrocyte membrane transport abnormalities of patients with sickle cell disease.

We show here that alpha2(G-Phila.) beta2(C) has an increased rate of crystal nucleation compared to alpha2 beta2(C) (HbC). We conclude from this finding that position alpha68, the mutation site of alpha2(G-Phila.) beta2 (HbG(Philadelphia)), is a contact site in the crystal of HbC. In addition, that HbS enhances HbC crystallization (additive to the effect of alpha(G-Phila.) as shown here) and that alpha(G-Phila.) inhibits polymerization of HbS are pathogenically relevant previously known facts. All of these findings help explain the phenotype of an individual simultaneously heterozygous for the betaS, betaC, and the alpha(G-Phila.) genes (SC alpha-G Philadelphia disease). This disease is characterized by a mild clinical course, abundant circulating intraerythrocytic crystals, and increased folded red cells. This phenotype seems to be the result of increased crystallization and decreased polymerization brought about by the opposite effects of the gene product of the alpha(G-Phila.) gene on the betaC and betaS gene products. Some of the intraerythrocytic crystals in this syndrome are unusually long and thin, resembling sugar canes, unlike those seen in SC disease. The mild clinical course associated with increased crystallization implies that, in SC disease, polymerization of HbS is pathogenically more important than the crystallization induced by betaC chains. The SC alpha-G Philadelphia disease is an example of multiple hemoglobin chain interactions (epistatic effect among globin genes) creating a unique phenotype.

Sickle cell disease (SCD) is characterized by repeated vaso-occlusive events, which result in substantial morbidity. Abnormal adhesion of sickle red blood cells (RBC) to the vascular endothelium is postulated to play a role in the pathogenesis of vaso-occlusion. Two adhesion receptors, very late activation antigen-4 (VLA-4) and CD36, are found in unusually high numbers on sickle cell reticulocytes and do mediate adhesion of sickle RBC to endothelium. Hydroxyurea (HU) therapy results in fewer vaso-occlusive episodes, and we postulated that HU-related modulation of VLA-4 and CD36 receptors may contribute to its clinical benefit. Using flow cytometry, eight patients were followed from the onset of HU treatment through a mean treatment length of 200 +/- 49 days. Mean corpuscular volume and percent fetal hemoglobin (Hb F) increased from 87% +/- 6% to 98% +/- 9% and 6.6% +/- 3.9% to 12.7% +/- 5.6%, respectively. The percentage of reticulocytes expressing VLA-4 decreased from 29.0% +/- 5.9% to 14.9% +/- 2.3% (P = .0003). Two thirds of the total decrease in VLA-4 expression occurred after 10 weeks of HU and plateaued by 20 weeks. Changes in VLA-4 expression occurred before substantial increases in Hb F. The percentage of reticulocytes expressing CD36 decreased from 55.3% +/- 6.4% to 42.6% (P = .0046). Changes in adhesion receptor expression were not caused by a decrease in reticulocytosis with HU therapy. This report is the first to associate a decrease in adhesion receptor expression with a therapy known to reduce the clinical severity of SCD.

Prevention of erythrocyte dehydration is a potential therapeutic strategy for sickle cell disease. Increasing erythrocyte magnesium (Mg) could inhibit sickle cell dehydration by increasing chloride (CI) and water content and by inhibiting potassium chloride (K-CI) cotransport. In transgenic SAD 1 and (control) C57BL/6 normal mice, we investigated the effect of 2 weeks of diet with either low Mg (6 +/- 2 mg/kg body weight/d) or high Mg (1,000 +/- 20 mg/kg body weight/ d), in comparison with a diet of standard Mg (400 +/- 20 mg/ kg body weight/d). The high-Mg diet increased SAD 1 erythrocyte Mg and K contents and reduced K-CI cotransport activity, mean corpuscular hemoglobin concentration (MCHC), cell density, and reticulocyte count. SAD 1 mice treated with low-Mg diet showed a significant reduction in erythrocyte Mg and K contents and increases in K-CI cotransport, MCHC, cell density, and reticulocyte counts. In SAD 1 mice, hematocrit (Hct) and hemoglobin (Hb) decreased significantly with low Mg diet and increased significantly with high-Mg diet. The C57BL/6 controls showed significant changes only in erythrocyte Mg and K content, and K-CI cotransport activities, similar to those observed in SAD 1 mice. Thus, in the SAD 1 mouse, changes in dietary Mg modulate K-CI cotransport, modify erythrocyte dehydration, and ultimately affect Hb levels.

Increased exposure of phosphatidylserine (PS) in erythrocytes has been postulated to contribute to the pathophysiology of sickle cell disease because of its possible effects on blood coagulation, cell adhesion, and cell clearance. We developed a flow-cytometric assay to measure exposure of PS on the outer face of the erythrocyte membrane based on addition of fluorescein-annexin V to whole-blood specimens. The assay correlated linearly with binding of 125I-annexin V (r2 = .95, n = 125 samples). Normal donors (n = 30) showed virtually no annexin-positive cells (0.34% +/- 0.18% for 24-hour old samples). In contrast, annexin V binding was above the upper limit of normal in 96% of 205 specimens from 17 adult sickle cell and 2 beta-thalassemia patients; the mean percentage of annexin-positive cells was 2.86% +/- 2.00% (range, 0.4% to 12.0%). Values varied substantially over time for some patients, and mean values varied between patients. The percentage of annexin-positive cells always decreased after transfusion (11 events in 6 patients), and out of proportion to the amount of blood transfused. In conclusion, increased exposure of PS on a subpopulation of erythrocytes in vivo is a virtually universal feature of sickle cell disease, and its measurement may be useful to evaluate clinical status and response to therapeutic measures such as blood transfusion.

We have characterized the erythrocytes, granulocytes, and platelets of 54 patients with paroxysmal nocturnal hemoglobinuria (PNH) with antibodies to glycosylphosphatidylinositol-anchored proteins (anti-CD55, anti-CD59, and anti-CD16) and flow cytometry to establish the usefulness of this technique in the diagnosis of this disorder. All patients demonstrated either completely (PNH III) or partially (PNH II) deficient red cells and granulocytes. Anti-CD59 best demonstrated PNH II red cells, which were present in 50% of the patients. The proportion of abnormal granulocytes was usually greater than the proportion of abnormal red cells; 37% of the patients had >80% abnormal granulocytes. Anti-CD55 did not delineate the erythrocyte populations as well as did anti-CD59. Either anti-CD55 or anti-CD59 could be used equally well to analyze granulocytes; anti-CD16 did not demonstrate cells of partial deficiency. Platelets could not be used for detailed analysis as the normal and abnormal populations were not well distinguished. Flow cytometry of erythrocytes using anti-CD59 or of granulocytes using either anti-CD55 or anti-CD59 provides the most accurate technique for the diagnosis of paroxysmal nocturnal hemoglobinuria; it is clearly more specific, more quantitative, and more sensitive than the tests for PNH that depend upon hemolysis by complement (the acidified serum lysis [Ham] test, the sucrose lysis test, and the complement lysis sensitivity [CLS] test).

We studied 20 individuals from 17 unrelated families with congenital dyserythropoietic anemia (type II; CDAII). The clinical phenotype was mild to moderate. The inheritance pattern was invariably recessive. Coomassie blue stained gels after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) show that band 3 was thinner and migrated slightly faster than usual. In addition, staining showed two unknown minor bands (in the patients), but not in normal controls, the obligate carrier parents, or in patients with other anemic syndromes. These minor proteins were studied using partial digestion, amino acid sequencing, Western blotting, immunofluorescence, and immunogold electron microscopy. They were identified as the glucose-regulated protein GRP78 and calreticulin that are resident proteins of the endoplasmic reticulum (ER). Using specific antibody, we showed that protein disulfide isomerase (PDI), a third major protein of the ER, was also present on the SDS-PAGE of red blood cell (RBC) ghosts. Immunofluorescence colocalized PDI with the dense discontinuous ring decorating the RBC membrane. Immunogold electron microscopy showed that PDI was localized in the lumen of the cisternae, confirming that these originate from the smooth ER. From a practical point of view, screening the above minor proteins in RBC membranes appears to be a straightforward and reliable diagnostic test for CDAII.

We have previously demonstrated that the membrane skeletons of irreversibly sickled cells (ISCs) dissociate more slowly at 37 degrees C, in high ionic strength Triton X-100 buffer, than do the membrane skeletons of reversibly sickled cells or control erythrocytes [Shartava et al. (1995) J. Cell. Biol. 128, 805-818]. Furthermore, we demonstrated that the major cause of this slow dissociation was a single posttranslational modification in ISC beta-actin. Two sulfhydryl groups (Cys284 and Cys373) became inaccessible to thiol reagents because of this modification. We suggested the possibility that the modification was a disulfide bridge between Cys284 and Cys373 since the reducing agent dithiothreitol restored the sulfhydryl groups. In this article, we directly demonstrate the existence of the disulfide bridge between cysteine284 and cysteine373 in ISC beta-actin. We synthesized the associated ISC beta-actin tryptic cystine-peptide (KCF-CDVDIR), characterized it by HPLC, MS. and MSMS, and identified it in the tryptic digest of the ISC beta-actin. These results support our earlier suggestion that the oxidative change in ISC beta-actin is a major cause of the irreversible sickling phenomenon.

beta thalassemia (beta thal) in DBA/2J mice is a consequence of the spontaneous and complete deletion of the beta major globin gene. Homozygous beta thal mice have clinical and biological features similar to those observed in human beta thal intermedia. Erythrocytes in human beta thal are characterized by a relative cell dehydration and reduced K+ content. The role of this erythrocyte dehydration in the reduced erythrocyte survival, which typifies the disease, has not previously been evaluated. We examined for 1 month the effects on the anemia and the erythrocyte characteristics of beta thal mice of daily treatment with either clotrimazole (CLT), an inhibitor of red blood cell (RBC) dehydration via the Gardos channel, or human recombinant erythropoietin (r-HuEPO), or hydroxyurea (HU). The use of either r-HuEPO or HU induced a significant increase in hemoglobin (Hb), hematocrit (Hct), erythrocyte K+ and a decrease in percent reticulocytes, suggesting improved erythrocyte survival. CLT alone decreased only mean corpuscular hemoglobin concentration (MCHC) and cell density and increased cell K+. Thus, though the Gardos channel plays a major role in cell dehydration of murine beta thal erythrocyte survival. Combination therapy with r-HuEPO plus HU produced no incremental benefit beyond those of single drug therapy. However, addition of CLT to r-HuEPO, to HU, or to combined r-HuEPO plus HU led to statistically significant increase in Hb, Hct, and erythrocyte K+ compared with any of the regimens without CLT. These results suggest that CLT not only inhibits erythrocyte dehydration, but also potentiates the erythropoietic and cellular survival responses to r-HuEPO and HU.

The phospholipids of the human red cell are distributed asymmetrically in the bilayer of the red cell membrane. In certain pathologic states, such as sickle cell anemia, phospholipid asymmetry is altered. Although several methods can be used to measure phospholipid organization, small organizational changes have been very difficult to assess. Moreover, these methods fail to identify subpopulations of cells that have lost their normal phospholipid asymmetry. Using fluorescently labeled annexin V in flow cytometry and fluorescent microscopy, we were able to identify and quantify red cells that had lost their phospholipid asymmetry in populations as small as 1 million cells. Moreover, loss of phospholipid organization in subpopulations as small as 0.1% of the total population could be identified, and individual cells could be studied by fluorescent microscopy. An excellent correlation was found between fluorescence-activated cell sorter (FACS) analysis results using annexin V to detect red cells with phosphatidylserine (PS) on their surface and a PS-requiring prothrombinase assay using similar red cells. Cells that bound fluorescein isothiocyanate (FITC)-labeled annexin V could be isolated from the population using magnetic beads covered with an anti-FITC antibody. Evaluation of blood samples from patients with sickle cell anemia under oxygenated conditions demonstrated the presence of subpopulations of cells that had lost phospholipid asymmetry. While only a few red cells were labeled in normal control samples (0.21% +/- 0.12%, n = 8), significantly increased (P < .001) annexin V labeling was observed in samples from patients with sickle cell anemia (2.18% +/- 1.21%, n = 13). We conclude that loss of phospholipid asymmetry may occur in small subpopulations of red cells and that fluorescently labeled annexin V can be used to quantify and isolate these cells.

Objective: Assay of spectrin in erythrocytes as a diagnostic test in hereditary spherocytosis (HS)., Design: Validation of a diagnostic test., Setting: Central Laboratory of the Netherlands Red Cross Blood Transfusion Service in Amsterdam, the Netherlands., Method: A radiolabelled rabbit antiserum against human spectrin was used to determine the amount of spectrin in erythrocytes from 64 patients with proven or supposed HS, suffering from inborn, sometimes familial anaemia and a decreased osmotic resistance of the erythrocytes. These amounts of spectrin were compared with those of 12 patients with decreased osmotic resistance suffering from haemolytic anaemia of unknown cause, 16 patients with various other erythrocyte disorders and 30 healthy blood donors., Results: The intradonor and interdonor variations in the amount of spectrin in erythrocytes from healthy blood donors were found to be less than 7%. In 56 of the 64 patients with HS (88%), the erythrocytes contained less than 86% of the normal amount of spectrin. A similar result was found in 4 of the 12 patients suffering from non-characterised haemolytic anaemia (33%). In contrast, a normal amount of spectrin was found in the erythrocytes of patients with other erythrocytic disorders., Conclusion: The radio-immunoassay of spectrin in erythrocytes is more specific for the diagnosis of HS than the osmotic fragility test of the erythrocytes. The normal amount of spectrin found in 8 of the 64 patients possibly suffering from HS may be due to a rare molecular origin of HS not leading to a decreased spectrin level or may be related to other causes of anaemia than HS.

Chemical cross-linking has been used to determine the composition of the erythrocyte band 3 protein dimer in Southeast Asian ovalocytes (SAO). Individuals with SAO are heterozygous for a mutation in which residues 400-408 of band 3 are deleted. Normal and variant protein are present in equal amounts, but the SAO protein does not transport anions or bind stilbenedisulfonates with high affinity. We find that the rate constant for 35SO4(2-) efflux from SAO cells is about 50% that of normal cells, but the time course is a single exponential, indicating that there is no detectable heterogeneity in the distribution of SAO band 3 in the population of cells. Treatment of intact cells with the homobifunctional crosslinker BS3 (bis[sulfosuccinimido]suberate) produces similar amounts of covalent dimer in both normal and SAO cells. In SAO cells, copies of normal band 3 can be distinguished from SAO band 3 by treating with H2DIDS to form a crosslink between major chymotryptic fragments (60 kDa and 35 kDa) within one subunit. Successive treatment of cells with [3H]-4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate ([3H]H2DIDS), BS3, and chymotrypsin gives 3H-labeled products that include homodimer of normal band 3 as well as products of crosslinking normal band 3 with the 60- and 35-kDa fragment of SAO band 3. The results are in semiquantitative agreement with a model in which covalent dimer forms between normal and SAO subunits with the same probability as between two normal subunits. These results indicate that the normal copy of band 3, complexed in a heterodimer with SAO band 3, reacts with H2DIDS as in normal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

We describe a nonsense mutation in the regulatory domain of erythroid ankyrin associated with autosomal dominant hereditary spherocytosis with a selective deficiency of the ankyrin isoform 2.1 (55% of normal), a deficiency of spectrin (58% of normal) proportional to the decrease in ankyrin 2.1, and a normal content of the other main ankyrin isoform, protein 2.2. PCR amplification of cDNA encoding the regulatory domain of ankyrin revealed a marked decreased in the ratio of ankyrin 2.1 mRNA to the ankyrin 2.2 mRNA. Sequencing of ankyrin gene in the region where the 2.1 and 2.2 mRNA differ detected a nonsense mutation 1669Glu-->Ter (GAA-->TAA) in one ankyrin allele. Only normal ankyrin 2.1 mRNA was detected in the reticulocyte RNA. Since the alternative splicing within the regulatory domain of ankyrin retains codon 1669 in ankyrin 2.1 mRNA and removes it from ankyrin 2.2 mRNA, we propose that the 1669Glu-->Ter mutation decreases the stability of the abnormal ankyrin 2.1 mRNA allele leading to a decreased synthesis of ankyrin 2.1 and a secondary deficiency of spectrin.