Leonid Livshits

Background: The Circassian community in Israel represents a unique, endogamous population residing in two villages in the northern region of Israel: Kfar Kama (209 meters above sea level [m.a.s.l.]) and Rihaniya (674 m.a.s.l.). Objectives: This study sought to investigate whether the small difference in altitude between these two locations (465 m) affects red blood cell (RBC) and hemoglobin (Hb) parameters in the residents. Methods: We examined the data from 2,517 blood samples collected from adult Israeli Circassians over 2.5 years (January 2020–June 2022). To ensure independent observations, analysis was limited to each participant’s most recent complete blood count (CBC). Subjects were stratified by sex, age, anemia status, and residential location. Results: Our analysis revealed that a difference of about 465 meters in residential altitude significantly elevated Hb, RBC count, and hematocrit (HCT) levels in non-anemic male and female cohorts. This eleva¬tion was accompanied by a small but significant decrease in mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). Furthermore, we found that the effect of altitude on most RBC character¬istics differed in anemic individuals of both sexes, although their RBC count still increased. Conclusions: Even minor differences in residential altitude can significantly influence Hb and RBC parameters. This observation appears only in non-anemic individuals, probably reflecting physiological altitude Hb adaptation mechanisms. While further research is needed to fully elucidate the underlying mechanisms, our findings provide new data on the physiological impact of altitude on human health, particularly at low altitudes.

Aging-related processes lead to significant metabolic and structural changes in red blood cells (RBCs) and, as a result, to heterogeneity in cell populations. Using the Percoll linear density gradient, separating the RBC population and obtaining fractions enriched with cells of different ages is possible. Previously, cells from the “light” fraction were characterized by increased deformability. However, the distribution of RBC deformability in subpopulations possessing a different density has not been studied. In this study, we measured the deformability of RBCs from cell fractions characterized by different densities. RBC deformability was determined using a computerized cell flow-properties analyzer, which provides the deformability distribution in a population of 10,000–15,000 cells. Our results demonstrate a strong correlation between the cytosol hemoglobin concentration and the cell deformation indexes. In addition, we show that the “lightest” fraction of RBCs contains the lowest number of deformable and the highest number of highly deformable cells. In contrast, the “dense” fraction is enriched with undeformable RBCs, with a minimal presence of highly deformable cells. In summary, we have shown that RBC fractions depleted or enriched with undeformable cells can be obtained by using a density gradient. However, these fractions are not homogeneous in their deformability properties.

Iron metabolism plays a crucial role in the management of hemoglobinopathies, particularly in conditions such as β-thalassemia and sickle cell anemia (SCA). This paper describes the mechanisms of iron overload in patients with transfusion-dependent thalassemia (TDT), non-transfusion-dependent thalassemia (NTDT), and SCA, highlighting the distinct paths leading to iron accumulation in each condition. The primary focus of this review article is on the role of genetic modifiers influencing iron metabolism and the variability in iron overload presentation among patients. Genetic mutations in genes such as HFE, HAMP, TFR2, SLC40A1, and others significantly impact iron regulation. These modifiers can exacerbate or ameliorate iron overload, and understanding these genetic factors is important for explaining the diverse disease severity and differences in the mechanism and clinical presentation of iron overload in these patients. The ongoing INHERENT study aims to further elucidate the influence of these genetic modifiers through a comprehensive genome-wide association study, potentially leading to novel therapeutic interventions for managing iron homeostasis in hemoglobinopathy patients.

The blood counts of α thalassemia carriers (α-thal) are similar to those of β thalassemia carriers, except for Hemoglobin A₂ (Hb A₂), which is not elevated. The objective of this study was to determine whether mathematical formulas are effective for detecting suspected α-thal. The data were obtained from the database of the prevention program for detecting couples at risk for having a child with hemoglobinopathy. Red Blood Cells (RBC) indices were analyzed using mathematical formulas, and the sensitivity and negative predictive value (NPV) were calculated. Among 1334 blood counts suspected of α-thal analyzed, only the Shine and Lal and the Support Vector Machine formulas revealed high sensitivity and NPV. Sensitivity was 85.54 and 99.33%, and NPV was 98.93 and 99.93%, respectively. Molecular defects were found in 291, and 81 had normal α genes. Molecular analysis was not performed in 962 of the samples. Based on these results, mathematical formulas incorporating one of these reliable formulas for detecting suspected α or β thalassemia carriers in the program of the automatic analyzers can flag these results, increase the awareness of the primary physicians about the carrier risk, and send an alert with a recommendation for further testing.

The deformability of red blood cells (RBCs), expressing their ability to change their shape as a function of flow-induced shear stress, allows them to optimize oxygen delivery to the tissues and minimize their resistance to flow, especially in microcirculation. During physiological aging and blood storage, or under external stimulations, RBCs undergo metabolic and structural alterations, one of which is hemoglobin (Hb) redistribution between the cytosol and the membrane. Consequently, part of the Hb may attach to the cell membrane, and although this process is reversible, the increase in membrane-bound Hb (MBHb) can affect the cell’s mechanical properties and deformability in particular. In the present study, we examined the correlation between the MBHb levels, determined by mass spectroscopy, and the cell deformability, determined by image analysis. Six hemoglobin subunits were found attached to the RBC membranes. The cell deformability was negatively correlated with the level of four subunits, with a highly significant inter-correlation between them. These data suggest that the decrease in RBC deformability results from Hb redistribution between the cytosol and the cell membrane and the respective Hb interaction with the cell membrane.

The blood counts of α thalassemia carriers (α-thal) are similar to those of β thalassemia carriers, except for Hgb A2 that is not elevated. The objective of this study was to determine whether mathematical formulas are effective for detecting suspected α-thal. The data were obtained from the database of the prevention program for detecting couples at risk for having a child with hemoglobinopathy. RBC indices were analyzed using mathematical formulas and the sensitivity and negative predictive value (NPV) calculated. Among 1334 blood counts suspected α-thal analyzed, only the Shine&Lal and the Support Vector Machine formulas revealed high sensitivity and NPV. Sensitivity was 85.54 and 99.33% and NPV 98.93 and 99.93%, respectively. Molecular defects were found in 291, 81 had normal α genes. Molecular analysis was not performed in 962. Based on these results, mathematical formulas incorporating one of these reliable formulas for detecting suspected α or β thalassemia carriers in the program of the automatic analyzers can flag these results and increase the awareness of the primary physicians about the carrier risk and send an alert with a recommendation for further testing.

The membrane-bound hemoglobin (Hb) fraction impacts red blood cell (RBC) rheology and metabolism. Therefore, Hb–RBC membrane interactions are precisely controlled. For instance, the signaling function of membrane-bound deoxy-Hb and the structure of the docking sites in the cytosolic domain of the anion exchanger 1 (AE-1) protein are well documented; however, much less is known about the interaction of Hb variants with the erythrocyte’s membrane. Here, we identified factors other than O₂ availability that control Hb abundance in the membrane-bound fraction and the possible variant-specific binding selectivity of Hb to the membrane. We show that depletion of extracellular Ca²⁺ by chelators, or its omission from the extracellular medium, leads to membrane-bound Hb release into the cytosol. The removal of extracellular Ca²⁺ further triggers the redistribution of HbA0 and HbA2 variants between the membrane and the cytosol in favor of membrane-bound HbA2. Both effects are reversible and are no longer observed upon reintroduction of Ca²⁺ into the extracellular medium. Fluctuations of cytosolic Ca²⁺ also impact the pre-membrane Hb pool, resulting in the massive transfer of Hb to the cellular cytosol. We hypothesize that AE-1 is the specific membrane target and discuss the physiological outcomes and possible clinical implications of the Ca²⁺ regulation of the intracellular Hb distribution.

Red blood cell (RBC) deformability, expressing their ability to change their shape, allows them to minimize their resistance to flow and optimize oxygen delivery to the tissues. RBC with reduced deformability may lead to increased vascular resistance, capillary occlusion, and impaired perfusion and oxygen delivery. A reduction in deformability, as occurs during RBC physiological aging and under blood storage, is implicated in the pathophysiology of diverse conditions with circulatory disorders and anemias. The change in RBC deformability is associated with metabolic and structural alterations, mostly uncharacterized. To bridge this gap, we analyzed the membrane protein levels, using mass spectroscopy, of RBC with varying deformability determined by image analysis. In total, 752 membrane proteins were identified. However, deformability was positively correlated with the level of only fourteen proteins, with a highly significant inter-correlation between them. These proteins are involved in membrane rafting and/or the membrane–cytoskeleton linkage. These findings suggest that the reduction of deformability is a programmed (not arbitrary) process of remodeling and shedding of membrane fragments, possibly mirroring the formation of extracellular vesicles. The highly significant inter-correlation between the deformability-expressing proteins infers that the cell deformability can be assessed by determining the level of a few, possibly one, of them.

Introduction: The commonly used method for hematocrit detection, by visual examination of microcapillary tube, known as "micro-HCT", is subjective but still remains one of the key sources for false hematocrit evaluation. Analytical automation techniques have increased standardization of RBC indexes detection; however, indirect hematocrit measurements by blood analyzer, the automated HCT, does not correlate well with "micro-HCT" results in patients with hematological pathologies. We aimed to overcome those disadvantages in "micro-HCT" analysis by using "ImageJ", processing software. Methods: 223 blood samples from the "general population" and 19 from sickle cell disease patients were examined in parallel for hematocrit values using the automated HCT, standard "micro-HCT" and "ImageJ" micro-HCT methods. Results: For the "general population" samples, the "ImageJ" values were significantly higher than the corresponding values evaluated by standard "micro-HCT" and automated HCT, except for the 0 to 2 months old newborns, in which the automated HCT results were similar to the "ImageJ" evaluated HCT. Similar to the "general population" cohort, we found significantly higher values measured by "ImageJ" compared to either "micro-HCT" or the automated HCT in SCD patients. Correspondent differences for the MCV and MCHC were also found. Conclusions: This study introduces "micro-HCT" assessment technique using the image-analysis module of "ImageJ" software. This procedure allows overcoming most of the data errors associated with the standard "micro-HCT" evaluation and can replace the use of complicated and expensive automated equipment. The presented results may be also used to develop new standards for calculations of hematocrit and associated parameters for routine clinical practice.