Red Blood Cell Size Research Articles

Investigations on Red Cell Size Distribution Histograms in Subjects Treated by Maintenance Haemodialysis

In forty-nine subjects on maintenance haemodialysis quantitative information with respect to changes in the erythron was derived from the red blood cell size distribution histogram. Increased values for the fraction of microcytes were observed in seventeen subjects, whereas in three subjects increased fractions of macrocytes were established. Both fractions were found to be increased simultaneously in only one subject. In the case of normal mean corpuscular volume (MCV) values, the fractions of microcytes were shown to be increased in four male and three female subjects. In contrast, MCV values were increased in four male subjects while the fractions of macrocytes did not exceed the reference range. Several causes which may give rise to abnormalities in red blood cell size distribution histograms in subjects treated by haemodialysis are discussed. From the interpretation of results for serum ferritin concentration, serum iron concentration, total iron binding capacity, and iron saturation percentage it is difficult to establish unequivocally whether the iron supply to the patient is appropriate.

Flow behavior of neonatal and adult erythrocytes in narrow capillaries

This study was designed to analyze the flow behavior of red blood cells (RBCs) in circular vessels with diameters of 3 to 6 μm by means of a mathematical model. According to this model, the RBC flow velocity is 1 mm/sec, RBCs assume axisymmetric shape, and the gap between the RBC and the vessel wall allows sufficient lubrication. The flow resistance depends on the surface area and volume of RBCs, the plasma viscosity, and the vessel diameter. Surface area and volume of RBCs from 10 term neonates and 10 adults were determined by means of a micropipet system and plasma viscosity was measured using a capillary viscometer. Neonatal RBCs had larger volumes (107 ± 6 fl vs 90 ± 4 fl) and surface areas (154 ± 7 μm 2 vs 137 ± 7 μm 2) than adult RBCs ( P < 0.005). Plasma viscosity was lower in neonates than in adults (1.04 ± 0.10 cP vs 1.26 ± 0.13 cP; P < 0.005). The flow model leads to the following conclusions: During the passage of 3- to 6-μm vessels, the large neonatal RBCs are more elongated than the smaller adult RBCs. In vessels with diameters of less than 3.3 μm, the rear of neonatal RBCs becomes convex, whereas this critical vessel diameter is 3.1 μm for adult RBCs. If the cells are suspended in the same medium, neonatal RBCs require a 31% higher driving pressure than adult RBCs to achieve the necessary elongation for passing through a narrow capillary. However, both cell types require similar driving pressures, if the cells are suspended in the corresponding plasma. The tube/discharge hematocrit ratio of neonatal RBCs is 1 to 6% higher than that of adult cells. Relative viscosity of neonatal RBCs is approximately 7% higher compared with adult RBCs, whereas the blood viscosity (relative viscosity times plasma viscosity) is 12% less in neonates than in adults. We conclude that the large size of neonatal RBCs may cause impaired flow in narrow vessels with diameters below the critical value of 3.3 μm. In vessels with diameters of 3.3–6.0 μm, the disadvantage of the large size of neonatal RBCs appears to be completely compensated for by the lower plasma viscosity in the neonate.

Oxygen transfer kinetics of red blood cells of the turtle Pseudemys scripta elegans

The kinetics of O 2 uptake into, and release from, the red blood cells (RBC) of the turtle Pseudemys scripta elegans were determined with a stopped-flow technique at varied temperature (10–30°C) and pH (7.5–7.9). The results were compared to those obtained for RBC of other vertebrates and related to morphometric and physiological data on gas/blood diffusion in turtle lungs. The O 2 transfer conductance of RBC, G, for O 2 release into high concentrations of dithionite, considered to represent the best estimate of true RBC transfer conductance for O 2 uptake and release, averaged 0.17 ± 0.01 at 30°C, 0.13 ± 0.01 at 20°C, 0.09 ± 0.01 at 10°C (mean ± SSD, in mmol·min −1·Torr −1·(mlRBC) −1). These values are about one half the corresponding value for human RBC, and this difference may be due to the larger size of turtle RBC (volume, 327 μm 3) compared to human RBC (90μm 3). The temperature dependence of G, Q 10 = 1.3 indicates that, as in human RBC, diffusion through aqueous media is the main limiting factor for O 2 exchange. Morphometric data on the lungs of Pseudemys scripta suggest that the resistance to O 2 transfer by RBC is lower than that offered by the gas-blood barrier. The total apparent transfer resistance to CO, obtained from previous measurements of pulmonary diffusing capacity for CO in the same species, is much higher than that predicted from the combination of RBC O 2 kinetics and morphometric data on gas-blood barrier.

Altitudinal distribution and blood values in the toad, Bufo spinulosus Wiegmann

1. 1. Red blood cell (RBC) count, RBC size, hematocrit, cell and blood hemoglobin concentrations and plasma total solid concentration were measured in 16 lowland (from near sea level up to 2700 m) and 18 highland (3200 up to close to 4500 m) adult toads ( Bufo spinulosus). 2. 2. Lowland toads showed higher hematocrit values than highland toads, but their blood hemoglobin concentration and plasma solid concentration were not significantly different. 3. 3. Highland toads had smaller RBC size, higher corpuscular hemoglobin concentration, a trend toward larger RBC count and a considerably smaller body size. These features may contribute to their successful life at high altitude.

Resistance of mammalian red blood cells of different size to hypertonic milieu

1. 1. The resistance of different mammalian red blood cells (RBCs) to hyperosmotic environments was studied. RBCs of six mammalian species were exposed to 10 increasingly hyperosmotic NaCl solutions for 24 hr at 5°C. 2. 2. The osmolality at which the amount of liberated haemoglobin reached a preset level (e.g. 3–4% of the total haemoglobin) showed a linear correlation with negative slope with RBC volume. This indicates that small RBCs are more resistant to hyperosmotic milieu than large ones. 3. 3. A similar relation can be found from literature data when maximal urinary tonicities are plotted as a function of RBC volume, i.e. animals with the ability to produce highly concentrated urine have small RBCs. 4. 4. RBC volume and maximal urinary tonicity in mammals are therefore tightly linked. Future research will have to show whether this correlation is fortuitous or not and whether, as can be speculated, RBC size is directly or indirectly regulated by the kidney.

Investigation of red cell size distribution histograms of normal male and female subjects

Size distribution histograms characterizing the red blood cell (RBC) populations of normal subjects are provided. Separate haemocytometric reference ranges were established for apparently healthy male and female adults by using an Ortho ELT 800 Hematology Analyzer, which is based on the principle of measuring light scattering intensity (LSI). Effects of sphering RBCs on some characteristics of size distribution histograms were also investigated. The absolute distribution width at half peak height (ADW0.5) of RBC size distribution histograms of sphered RBCs is shown to be approximately 40% lower than for unsphered RBCs. The mean RBC size distribution histogram determined for the group of female subjects was shown to be significantly shifted to the right in comparison with the mean size distribution histogram calculated for males, indicating a sex-related difference. The shift is concordant with a significantly higher fraction of microcytes in male subjects, as well as with lower mean corpuscular volume (MCV) values in males compared with females.

Some effects on light scattering intensity and red blood cell size distribution histograms due to sphering.

At present most haematology blood cell analysers routinely provide red blood cell (RBC) size distribution histograms. Sophisticated improvements of the instruments have re-awakened interest in the study of size histograms. The quantitative information derived from the histograms may be applied more fruitfully if insight is available, with respect to some essential principles of sizing technology and methods for treatment of RBCs before measurement. In this study the consequences of sphering RBCs are investigated in relation to the generation of size distribution histograms by means of methods based on light scattering intensity (LSI). Sphering of RBCs results in considerably narrower histograms than upsphered RBCs. The overall signal to noise ratio increases and there is a broader gap between large platelets and microcytic RBCs. Narrower size distribution ranges will enable closer modes to be separated. Compared to unsphered RBCs, microcytic sphered RBCs yield increased LSI whereas macrocytic sphered RBCs yield decreased LSI.

Evaluation of red blood cell size distribution histograms: the fraction of microcytes.

A method is described for the assessment of the fraction of microcytes from the red blood cell (RBC) size distribution histogram. For quantification of the fraction of microcytes an upper threshold corresponding with a RBC volume of 70 fL is established. The reference interval for the fraction of microcytes covers a range from 0.01 to 0.09. In order to examine the relationship between the fraction of microcytes and the mean cell volume (MCV) values computer simulation studies were performed. The computer simulations are based on a Gaussian distributed reference RBC histogram as generated on a Technicon H 6000/H 601 Hematology Analyser. From our studies it is shown that determination of the fraction of microcytes yields a higher sensitivity than MCV values for detecting small populations of microcytes. In particular, measurement of the fraction of microcytes is very sensitive to minor changes in the MCV values if a normocytic RBC population combined with a microcytic RBC fraction shows a wide dispersion in their cell volumes.

Comparison of Mie theory and the light scattering of red blood cells

Two important optical properties of red blood cells (RBCs), their microscopic scattering cross sections sigma(s), and the mean cosine of their scattering angles micro, contribute to the optical behavior of whole blood. Therefore, the ability of Mie theory to predict values of sigma(s) and was tested by experiment. In addition, the effect of red blood cell size on sigma(s) and micro was investigated in two ways: (1) by studying erythrocytes from the dog, goat, and human, three species known to have different RBC sizes and (2) by allowing the RBCs from each species to shrink or swell osmotically. Values of sigma(s) obtained by measuring the collimated transmittance of dilute RBC suspensions illuminated with a He-Ne laser agreed with those predicted by Mie theory. Moreover, measured as values were directly proportional to RBC volume. By contrast, values of from Mie theory were consistently greater than those obtained experimentally by making angular scattering measurements in a goniometer. Thus Mie theory appears to yield adequate values for the RBC's microscopic scattering cross section, but by treating the RBC as a sphere with an equal volume, Mie theory fails to take the RBC's anisotropy into account and thus yields spuriously high values for micro.

Does red blood cell size correlate with red blood cell age in mouse?

Mouse red blood cells (RBC) can be fractionated according to their size by counterflow centrifugation. The mean corpuscular hemoglobin content and the enzyme activities (ASAT, LDH, PK and acetylcholinesterase) increase when the mean corpuscular volume (MCV) rises. However, the in-vivo survival of size-separated RBC is similar whatever their MCV is; thus, counterflow centrifugation is not a suitable procedure to achieve an age fractionation of mouse RBC. Moreover, RBC subpopulations collected by counterflow centrifugation are different from those obtained when RBC are fractionated according to their density.

Red Blood Cell Fragmentation: Improved Detection and Identification of Causes

The peripheral blood film and the red blood cell size distribution histogram were examined for evidence of red blood cell fragments in 2,350 subjects. To distinguish subjects with greater than or equal to 10 fragments/1,000 red blood cells (abnormal) from normal, examination of the blood film was 0.83 sensitive and 0.30 specific, whereas examination of the histogram was 0.97 sensitive and 0.87 specific. The most common causes of abnormal fragmentation were malignancy with cytotoxic chemotherapy and severe iron deficiency. In two subjects, an abnormal red blood cell fragmentation pattern was the clue to a spectrin mutant in subjects with an automated blood count previously evaluated as normal. The data suggest two conclusions: the red blood cell volume histogram appears more accurate than the peripheral blood film for routine identification of red blood cell fragments; and asymptomatic spectrin abnormality identifiable by abnormal histogram may be a relatively common disorder.

26 FLOW BEHAVIOR OF NEONATAL AND ADULT ERYTHROCYTES IN VESSELS WITH DIAMETERS OF 3 TO 6 μm

This study was designed to analyse the flow behavior of red blood cells (RBC) by means of a mathematical model. According to this model, the flow resistance depends on the gap between RBC and vessel wall and on the plasma viscosity. Surface area (SA) and volume (V) of RBC from ten term neonates (N) and ten adults (A) were measured by means of a micropipette system and plasma viscosity (PV) was determined using a capillary viscometer. Neonatal RBC had larger V and SA than adult RBC (107 ± 6 vs 90±4 fl, and 154±7 vs 137±7 μm3). PV was lower in neonates (1.04±0.10 cP) than in adults (1.26±0.13 cP). The critical vessel diameter below that the gap becomes too small to allow sufficient lubrication is higher for neonatal RBC (3.3μm) than that for adult RBC (2.9μm). The driving pressure, hematocrit and viscosity of neonatal RBC is higher than that of adult RBC if both cell types have been suspended in the same medium. However, the driving pressure and viscosity of neonatal and adult RBC is similar for neonatal and adult RBC if the cells have been suspended in the corresponding neonatal and adult plasma. We conclude that the flow properties of neonatal and adult RBC in vessels with diameters of 3.5 to 6 μm are not different since the larger size of neonatal RBC is compensated by a lower PV.

RED-CELL-VOLUME DISTRIBUTION CURVES IN DIAGNOSIS OF GLOMERULAR AND NON-GLOMERULAR HAEMATURIA

The distribution curves of urinary redblood-cell (RBC) size were obtained from automated blood-cell analysis in 146 patients with definite causes of haematuria. In 65 of 67 patients (97%) with haematuria and glomerulonephritis demonstrated by renal biopsy, urinary RBC had an irregular and asymmetrical distribution with RBC size showing a much smaller volume than that of venous RBC. This "glomerular" distribution contrasted with the "non-glomerular" normal distribution when the peak for RBC was at a larger volume than that for peripheral RBC. In 46 of 47 patients with haematuria who had lower urinary tract lesions other than infection, a non-glomerular distribution was obtained; 30 of these cases also showed glomerular distribution, and were classified as "mixed". All 32 patients with urinary tract infection had either a glomerular or mixed distribution, suggesting that they excreted distorted and dysmorphic urinary RBC. After excluding infections, this simple, rapid, reproducible, and non-invasive technique provides reliable information in distinguising glomerular bleeding from other causes of haematuria.

Erythrocyte anisocytosis. Visual inspection of blood films vs automated analysis of red blood cell distribution width.

An improved anemia classification may be available by combining measures of red blood cell size variability with mean corpuscular volume. Visual inspection of the peripheral blood film allows semiquantitative description of anisocytosis while quantitative measures are determined from electronic cell counter analyzers' red blood cell distribution width. We evaluated correlations between semiquantitative and quantitative measures of anisocytosis for different groups of observers. Hematologists', medical students', and medical residents' semiquantitative assessment of anisocytosis correlated with the quantitative red blood cell distribution width. The interobserver variability demonstrated that all observers correlated with each other, while the intraobserver variability of semiquantitative anisocytosis demonstrated that observers were more precise than could be predicted by chance. However, the extreme precision of the red blood cell distribution width strongly suggests that it should be the "gold standard" for measuring red blood cell size variability.

Erythrocyte Anisocytosis

An improved anemia classification may be available by combining measures of red blood cell size variability with mean corpuscular volume. Visual inspection of the peripheral blood film allows semiquantitative description of anisocytosis while quantitative measures are determined from electronic cell counter analyzers' red blood cell distribution width. We evaluated correlations between semiquantitative and quantitative measures of anisocytosis for different groups of observers. Hematologists', medical students', and medical residents' semiquantitative assessment of anisocytosis correlated with the quantitative red blood cell distribution width. The interobserver variability demonstrated that all observers correlated with each other, while the intraobserver variability of semiquantitative anisocytosis demonstrated that observers were more precise than could be predicted by chance. However, the extreme precision of the red blood cell distribution width strongly suggests that it should be the "gold standard" for measuring red blood cell size variability.

Measurements on the forward light scattering intensities of monodisperse latex particles and sphered or unsphered red blood cells.

Characteristics with respect to light scattering intensity (LSI) were measured on latex spheres and on sphered and unsphered red blood cells (RBC). From the discrepancies in LSI signals from polymer spheres and RBCs it is obvious that latices cannot be used for absolute calibration of RBC sizes. Sphering of RBCs did not give rise to a closer resemblance. Monodisperse latex spheres produce extremely narrow size distribution histograms. Regarding these sharp peaks and the long-term stability, polymer spheres offer definite advantages if compared with blood controls to which preservatives were added. A shift from the RBC size distribution histogram, caused by gradually developing instrument drift, can be easily detected and corrected at an early stage.

Effects of loading density on carbohydrate metabolism and hematology in the Indian freshwater catfish, Heteropneustes fossilis

Tissue glycogen and blood glucose concentrations, blood chloride values, and eight hematological parameters were determined in groups of common Indian freshwater catfish, Heteropneustes fossilis, held at four different loading densities, namely, 0.99, 1.485, 1.98 and 2.475 fish cm/l (biomass densities of 3.42, 5.13, 6.84 and 8.55 kg/m 3) of water and compared to parallel control groups with a desirable loading density of 0.495 fish cm/l (1.71 kg/m 3) of water. High loading densities induced both liver and muscle glycogenolysis with concomitant hyperglycemia, hyperchloremia, significant decrease in the size of red blood cells, erythrocytosis, significantly increased hemoglobin content and hematocrit, markedly decreased erythrocyte sedimentation rate, leucopenia (due to lymphopenia), thrombocytopenia, and hypocoagulability of the blood.

Altered shape and size of red blood cells in obese hyperglycaemic mice.

Red blood cells (RBCs) from hyperglycaemic ob/ob-mice, normoglycaemic controls, and a healthy man were sucked into a narrow capillary, photographed and measured. Mouse RBCs had a smaller diameter than human ones. Although of normal diameter, the ob/ob-mouse RBCs exhibited increased area and volume, and more frequently than control RBCs had a minimum cylindrical diameter greater that 3 micron. Cross-sectional profiles with minimum bending resistance were computed for RBCs of mean area and volume. The diameters of these theoretical profiles agreed closely with those empirically observed, in both mice and man. The profile of ob/ob-mouse RBCs predicted a greater resistance to corpuscle bending than the control profile. It is concluded that changes in shape and size explain the decreased filtrability of diabetic ob/ob-mouse RBCs. The results also suggest that the actually occuring smooth biconcavity is in general the RBC shape with maximum flexibility.

Hereditary sideroblastic anaemia and autosomal inheritance of erythrocyte dimorphism in a Dutch family

Size distribution curves of red blood cells were used to detect the presence of microcytes in peripheral blood of members of a Dutch family with hereditary sideroblastic anaemia. 22 of 49 members of this family have a bimodal erythrocyte volume distribution curve and a dimorphic blood picture. The pattern of inheritance of this morphological abnormality is clearly autosomal. It is suggested that the study of red blood cell size distribution curves may add valuable information on the pattern of inheritance in other families with hereditary sideroblastic anaemia.

Multi-Phase Flow Model of Blood Flow

Blood is a suspension of blood cells in a Newtonian fluid of plasma. The red blood cells (RBCs) are most numerous and behave like small deformable capsules containing a Newtonian fluid. How to treat blood flowing through vessels depends on the scale involved. The flow characteristics of blood in the microvessel with a diameter comparable with the RBC size may be determined by the behavior of individual RBCs, for which a multi-phase flow model may provide a good approximation. Some multiphase flow problems of blood flow are studied.