Membrane alterations leading to red cell destruction

Modeling erythrocyte electrodeformation in response to amplitude modulated electric waveforms

We present a comprehensive theoretical-experimental framework for quantitative, high-throughput study of cell biomechanics. An improved electrodeformation method has been developed by combing dielectrophoresis and amplitude shift keying, a form of amplitude modulation. This method offers a potential to fully control the magnitude and rate of deformation in cell membranes. In healthy human red blood cells, nonlinear viscoelasticity of cell membranes is obtained through variable amplitude load testing. A mathematical model to predict cellular deformations is validated using the experimental results of healthy human red blood cells subjected to various types of loading. These results demonstrate new capabilities of the electrodeformation technique and the validated mathematical model to explore the effects of different loading configurations on the cellular mechanical behavior. This gives it more advantages over existing methods and can be further developed to study the effects of strain rate and loading waveform on the mechanical properties of biological cells in health and disease.

Cisplatin-loaded Au–Au2S nanoparticles for potential cancer therapy: Cytotoxicity,in vitro carcinogenicity, and cellular uptake

Cisplatin is one of the most effective cytotoxic agents against cancers. Its usage, however, is limited because of severe resistance and systemic toxicity. A formulation of cisplatin-loaded Au-Au(2)S nanoparticles (NPs) with near-IR (NIR) sensitivity is reported to partly overcome this limitation in this paper. NIR sensitive Au-Au(2)S NPs were successfully synthesized by the reduction of tetrachloroauric acid (HAuCl(4)) using sodium sulfide (Na(2)S), and cisplatin was loaded onto Au-Au(2)S NPs via a MUA (11-mercaptoundecanoic acid) layer. To further investigate the biological safety of cisplatin-loaded Au-Au(2)S NPs, three different cell lines were used to investigate the acute cytotoxicity and the long-term potential carcinogenicity in vitro. Cisplatin-loaded Au-Au(2)S NPs were also tested for limited hemocompatibility in vitro. Our in vitro short and long-term data provided preliminary evidence suggesting that cisplatin-loaded Au-Au(2)S NPs with NIR sensitivity are nontoxic below the maximum recommended dosage.

Red cell osmotic fragility studies in hemoglobin C-β thalassemia: osmotically resistant microspherocytes

Typically certain features of red cell morphology predict the results of osmotic fragility testing. Microspherocytes generally have increased and target cells decreased fragility. Blood smears in homozygous hemoglobin C disease show an interesting admixture of microspherocytes and target cells. Yet osmotic fragility studies generally show only reduced fragility and no population of fragile cells to correspond with the spherocytes. The present study demonstrates that the red cells of patients with hemoglobin C-beta thalassemia share many characteristics with hemoglobin C red cells, including the decreased osmotic fragility of all cells despite the presence of both spherocytes and target cells. These paradoxically osmotically resistant spherocytes probably arise because of cellular dehydration due to a K-Cl transport system which may be activated by binding of hemoglobin C to the red cell membrane.

Qualitative evaluation of irregularly spiculated red blood cells in the dog

Irregularly speculated red blood cells (IS-RBC) were quantified on fresh blood fixed in glutaraldehyde and were compared to RBC shape changes observed on Wright's-stained blood smears, RBC histograms, and RBC distribution widths (RDW). IS-RBC were infrequently found in healthy control dogs. Twenty dogs with increased IS-RBC were evaluated. The most common clinical diagnoses were lymphosarcoma (seven cases), glomerulonephritis (two cases), hemangiosarcoma (two cases), and chronic liver disease (two cases). Five cases had evidence of disseminated intravascular coagulopathy. In 12 of the 20 cases, keratocytes, schizocytes, and/or acanthocytes were detected in the monolayer area of blood smears. In the other seven cases, keratocytes, schizocytes, and/or acanthocytes were found only in thick areas of the smears. Acanthocytes were the most frequent cell type seen, while schizocytes were absent or present only in low numbers. RBC histograms had a shoulder on the left side of the tracing in six of the 20 cases, suggesting the presence of RBC fragments; however, cases with evidence of platelet aggregation had similar shoulders in RBC histograms. Red cell distribution widths were increased in 12 of the 20 cases with IS-RBC; however, the increase in RDW did not correlate with the presence of schizocytes and was most likely the result of reticulocytosis. This study suggests that quantitative evaluation of RBC shape is a more sensitive method for detection of mild RBC fragmentation when compared to blood smear evaluation, RBC histograms, or RDW. Additionally, acanthocyte-type cells were the most frequent shape change seen in dogs with evidence of RBC fragmentation.

Splenectomy prolongs in vivo survival of erythrocytes differently in spectrin/ankyrin- and band 3–deficient hereditary spherocytosis

Red cell (RBC) deformability and membrane-bound immunoglobulin G (IgG) were studied to better understand premature clearance of erythrocytes in hereditary spherocytosis. Averaged deformability profiles from cells having comparable cell age revealed that splenectomy was more beneficial for spectrin/ankyrin-deficient than for band 3–deficient RBCs. Splenectomy prevented an early loss of young cells in both types of deficiencies. It had an additional beneficial effect on spectrin/ankyrin-deficient but not band 3–deficient RBCs. It prolonged the survival of mature spectrin/ankyrin-deficient RBCs such that they lost their deformability more slowly than RBCs from patients who had not undergone splenectomy. Band 3–deficient RBCs lost their deformability at the same rate before and after splenectomy. In HS patients with band 3 deficiency who underwent splenectomy, RBC deformability inversely correlated with the number of RBC-bound IgG (up to 140 molecules per cell). In spectrin/ankyrin deficiency, RBC-bound IgG remained at control levels (60 IgG or less per cell). It appears that spectrin/ankyrin-deficient RBCs escaped opsonization by releasing band 3–containing vesicles because their band 3 content and deformability dropped in parallel with increasing cell age. Band 3–deficient RBCs did not lose band 3 with increasing cell age. Hence, it is possible that band 3 clusters required for bivalent binding of low-affinity–IgG, naturally occurring antibodies were retained in band 3–deficient RBCs with a relative excess of skeletal proteins but were released from spectrin/ankyrin-deficient RBCs, in which vesicle budding was facilitated by an impaired skeleton.

Splenectomy prolongs in vivo survival of erythrocytes differently in spectrin/ankyrin- and band 3–deficient hereditary spherocytosis

Red cell (RBC) deformability and membrane-bound immunoglobulin G (IgG) were studied to better understand premature clearance of erythrocytes in hereditary spherocytosis. Averaged deformability profiles from cells having comparable cell age revealed that splenectomy was more beneficial for spectrin/ankyrin-deficient than for band 3–deficient RBCs. Splenectomy prevented an early loss of young cells in both types of deficiencies. It had an additional beneficial effect on spectrin/ankyrin-deficient but not band 3–deficient RBCs. It prolonged the survival of mature spectrin/ankyrin-deficient RBCs such that they lost their deformability more slowly than RBCs from patients who had not undergone splenectomy. Band 3–deficient RBCs lost their deformability at the same rate before and after splenectomy. In HS patients with band 3 deficiency who underwent splenectomy, RBC deformability inversely correlated with the number of RBC-bound IgG (up to 140 molecules per cell). In spectrin/ankyrin deficiency, RBC-bound IgG remained at control levels (60 IgG or less per cell). It appears that spectrin/ankyrin-deficient RBCs escaped opsonization by releasing band 3–containing vesicles because their band 3 content and deformability dropped in parallel with increasing cell age. Band 3–deficient RBCs did not lose band 3 with increasing cell age. Hence, it is possible that band 3 clusters required for bivalent binding of low-affinity–IgG, naturally occurring antibodies were retained in band 3–deficient RBCs with a relative excess of skeletal proteins but were released from spectrin/ankyrin-deficient RBCs, in which vesicle budding was facilitated by an impaired skeleton.

Atomic force microscopic observation of mechanically traumatized erythrocytes

Erythrocytes are damaged or stimulated mechanically by artificial organs assisting in circulation. For several decades, a large number of research studies have been conducted to investigate the traumatizing phenomena due to nonphysiological flow conditions. These phenomena are thought to be the physical interaction between the cell membrane and the various fluidic conditions. To elucidate or evaluate the phenomena, however, chemical components emerging into the circulating solution, such as liberated hemoglobin or lactic dehydrogenase (LDH), have been measured as a main parameter. Naturally, the physical reaction caused on the membrane itself cannot be detailed by these parameters because they are the secondary products resulting from the mechanical membrane rupture. The aim of this study is to understand the traumatizing mechanism directly from a microbiological viewpoint. As a first step, we visualized the surface of sheep erythrocytes loaded with shear stress and measured erythrocyte surface roughness by atomic force microscopy (AFM) on a nanometer scale (10(-9) m). The constant shear rate was set at 1,800 (1/s), and the exposure time was set at 0.5, 1, and 2 h. We also measured the liberated hemoglobin concentration. As a result, it was found that the fine structure on the cell surface was changed drastically by the stress. It was also found that the surface roughness value increased with the exposure time, and correlated to the hemoglobin concentration. The visualization and the measurement of surface roughness of traumatized erythrocytes by AFM were thought to offer a new parameter for both hemolytic and subhemolytic studies.

Decreased lipid fluidity of the erythrocyte membrane in dogs with leishmaniasis-associated anaemia

In both man and the dog, anaemia resulting from natural leishmaniasis is often severe and mainly associated with a shortened life span of erythrocytes. Lipid fluidity of erythrocyte membranes from 17 dogs with anaemia caused by visceral leishmaniasis was investigated by means of fluorescence polarization. Results were compared with those from three groups of control animals (10 healthy dogs, seven dogs with visceral leishmaniasis but no anaemia, and 10 dogs with anaemia unrelated to leishmaniasis). Fluorescence polarization values recorded for animals with leishmaniasis-associated anaemia were elevated-indicating reduced erythrocyte membrane fluidity-and significantly higher than in the control groups. Mechanical sequestration by the spleen due to increased cell rigidity, or alterations in receptor/ligand erythrocyte cytoadherence mechanisms, or both, may result from decreased membrane fluidity and hence contribute to the anaemia of Leishmania -infected dogs.

Cellular and molecular mechanisms of senescent erythrocyte phagocytosis by macrophages. A review

Human red blood cells (RBCs) have a life-span of 120 days in circulation, after which they are phagocytized by resident macrophages. Extensive studies have been undertaken by many investigators in order to elucidate the cellular and molecular mechanisms of the erythrophagocytosis. The critical questions addressed by physiologists, clinicians and biochemists are: 'which of the many traumatic blemishes that appear on the erythrocyte surface as it winds its way through the circulation is the primary signal for clearance of the effete RBC from the circulation?', or 'What is the critical signal that it, and it alone, will activate the resident macrophage to adhere to and engulf it?'. Numerous, and often conflicting, hypotheses have been proposed. Each investigator focusing on but one of the many modifications that afflict the cell surface of the ageing erythrocyte, viz changes in either or both the carbohydrate or peptidic moieties of glycoproteins; abolishment of the pre-existing asymmetry in the lipid bilayer with the exposure of phosphatidylserine residues; or alterations in spectrin, to mention but a few. Many of these investigators also have invoked an intermediary role for auto-immune antibodies that recognise the change(s) on the erythrocyte surface and thereby serve as opsonins as a prelude to the erythrophagocytosis. The objective of the present review is to evaluate the data in support of the various hypotheses, and to submit some of our own recent observations involving the use of flow cytometric procedures that: i) provide evidence that the cell surface sialic acid serves as a determinant of the life-span; ii) characterise the senescent erythrocyte population that is specifically captured and phagocytized by macrophages (utilising the rapid and sensitive procedure we developed for quantification of in vitro erythrophagocytosis); and finally iii) provide evidence for the existence of an alternative pathway that is independent of immunoglobulins.

Presence in Human Erythrocyte Membranes of a Novel Form of Sialidase Acting Optimally at Neutral pH

The feature of intact human erythrocytes and erythrocyte white ghosts is a unique sialidase activity with acidic optimal pH (acidic sialidase). The treatment of white ghosts with mildly alkaline isotonic solutions at 37°C, like that used to produce resealed ghosts, is accompanied by the expression, together with the acidic sialidase, of a novel sialidase with a pH optimum of 7.2 (neutral sialidase) that remained masked in the inside-out vesicles prepared from white ghosts. Exhaustive treatment of resealed ghosts with Bacillus Thuringiensis phosphatidylinositol-specific phospholipase C causes an almost complete release of the acidic sialidase, with the neutral enzyme remaining totally unaffected. The treatment of resealed ghosts with 1.2% Triton X-100 resulted in the solubilization of only the neutral sialidase, whereas 3.6% octylglucoside also solubilized the acidic sialidase. The neutral enzyme affected not only the artificial substrate but also any sialoderivatives of a ganglioside, glycoprotein, and oligosaccharide nature; the acidic enzyme did not affect sialoglycoproteins. Erythrocyte endogenous gangliosides were hydrolyzed by both sialidases, whereas the endogenous sialoglycoproteins responded to only the neutral enzyme. It was definitely proved that the acidic sialidase is located on the outer erythrocyte membrane surface, so presumably the neutral enzyme has the same location. It could be that the newly discovered neutral sialidase has a physiologic role in the releasing of sialic acid from erythrocytes during the erythrocyte aging process, leading to eventual phagocytosis by macrophages.

Mechanisms of hemolysis with mitral prosthetic regurgitation. Study using transesophageal echocardiography and fluid dynamic simulation

OBJECTIVES

The aims of this study were to define the hydrodynamic mechanisms involved in the occurrence of hemolysis in prosthetic mitral valve regurgitation and to reproduce them in a numeric simulation model in order to estimate peak shear stress.

BACKGROUND

Although in vitro studies have demonstrated that shear stresses > 3,000 dynes/cm2 are associated with significant erythrocyte destruction, it is not known whether these values can occur in vivo in conditions of abnormal prosthetic regurgitant flow.

METHODS

We studied 27 patients undergoing reoperation for significant mitral prosthetic regurgitation, 16 with and 11 without hemolysis. We classified the origin and geometry of the regurgitant jets by using transesophageal echocardiography. By using the physical and morphologic characteristics defined, several hydrodynamic patterns were simulated numerically to determine shear rates.

RESULTS

Eight (50%) of the 16 patients with hemolysis had paravalvular leaks and the other 8 had a jet with central origin, in contrast to 2 (18%) and 9 (82%), respectively, of the 11 patients without hemolysis (p = 0.12, power 0.38). Patients with hemolysis had patterns of flow fragmentation (n = 2), collision (n = 11) or rapid acceleration (n = 3), whereas those without hemolysis had either free jets (n = 7) or slow deceleration (n = 4) (p < 0.001, power 0.99). Numeric simulation demonstrated peak shear rates of 6,000, 4,500, 4,500, 925 and 950 dynes/cm2 in these five models, respectively.

CONCLUSIONS

The distinct patterns of regurgitant flow seen in these patients with mitral prosthetic hemolysis were associated with rapid acceleration and deceleration or high peak shear rates, or both. The nature of the flow disturbance produced by the prosthetic regurgitant lesion and the resultant increase in shear stress are more important than the site of origin of the flow disturbance in producing clinical hemolysis.

Elevated 2,3-diphosphoglycerate concentrations and alteration of structural integrity in the erythrocytes of Indian cases of visceral leishmaniasis

The visceral leishmaniasis (VL) known as kala-azar in India is characterized by severe anaemia. The anaemia seems to be the result, at least in part, of the relatively short life-time of the erythrocytes, which have weakened cell membranes, possibly because of elevated concentrations of 2,3-diphosphoglycerate (2,3-DPG). There is a negative correlation (r = 0.91; P < 0.01) between erythrocytic 2,3-DPG concentrations and the blood concentration of haemoglobin, and the erythrocytes from infected patients display higher osmotic fragility than those from uninfected controls. Spectrofluorometry, using 1,6-diphenyl 1,3,5-hexatriene as a probe, indicated that fluorescence depolarization and microviscosity are also higher in the erythrocytic membranes from VL cases than in those from the controls. The cholesterol/phospholipid ratio is also relatively high in the membranes from the VL cases and there is degradation of the skeletal components and the major integral protein (band 3). The enhanced concentration of 2,3-DPG may be related to the altered structural integrity of the erythrocytes and this may lead to anisocytosis and the reduction in the erythrocytic half life.

Flow cytofluorimetric analysis of young and senescent human erythrocytes probed with lectins. Evidence that sialic acids control their life span

Comparing the properties of 'young' and senescent ('aged') O+ erythrocytes isolated by applying ultracentrifugation in a self-forming Percoll gradient, we demonstrate that the sialic acids of membrane glycoconjugates control the life span of erythrocytes and that the desialylation of glycans is responsible for the clearance of the aged erythrocytes. This capture is mediated by a beta-galactolectin present in the membrane of macrophages. The evidence supporting these conclusions is as follows: (1) Analysis by flow cytofluorimetry of the binding of fluorescein isothiocyanate labelled lectins specific for sialic acids shows that the aged erythrocytes bind less WGA, LPA, SNA and MAA than young erythrocytes. The binding of DSA and LCA is not modified. On the contrary, the number of binding sites of UEA-I specific for O antigen and of AAA decreases significantly. PNA and GNA do not bind to erythrocytes. (2) RCA120 as well as Erythrina cristagalli and Erythrina corallodendron lectins specific for terminal beta-galactose residues lead to unexpected and unexplained results with a decrease in the number of lectin binding sites associated with increasing desialylation. (3) The glycoconjugates from the old erythrocytes incorporate more sialic acid than the young cells. This observation results from the determination of the rate of transfer by alpha-2,6-sialyltransferase of fluorescent or radioactive N-acetylneuraminic acid, using as donors CMP-9-fluoresceinyl-NeuAc and CMP-[14C]-NeuAc, respectively. (4) Microscopy shows that the old erythrocytes are captured preferentially by the macrophages relative to the young ones. Fixation of erythrocytes by the macrophage membrane is inhibited by lactose, thus demonstrating the involvement of a terminal beta-galactose specific macrophage lectin. (5) Comparative study of the binding of WGA, LPA, SNA and MAA to the aged erythrocytes and to the in vitro enzymatically desialylated erythrocytes shows that the desialylation rate of aged cells is low but sufficient to lead to their capture by the macrophages.

Lipid peroxidation of erythrocytes during anemia of the hamsters infected with Leishmania donovani

Visceral leishmaniasis has been found to be associated with severe anemia and premature lysis of erythrocytes. Peroxidative damage of red cells has been noted in several hemolytic anemias. Present study shows enhanced formation of methemoglobin in hamsters infected with Leishmania donovani. Increased formation of malonyldialdehyde and diene conjugate has been noted in the erythrocytes of the infected animals with the progress of anemia. Results showed decreased activities of protective enzymes like superoxide dismutase, catalase and glutathione reductase against peroxidative attack. An increase in the membrane cholesterol/phospholipid ratio and a decrease in membrane fluidity of erythrocytes were observed under the diseased condition. Densitometric scan after SDS-PAGE of red cell membrane of the infected animals revealed significant degradation of band 3 and band 4.1 proteins. The results suggest that alteration in the membrane may lead to reduced life span of the red cells in experimental visceral leishmaniasis.

Flow cytometric analysis of human erythrocytes: I. Probed with lectins and immunoglobulins

A recent review (Aminoff, 1988) summarized the evidence for and against our hypothesis for the role of glycophorin in the senescence and clearance of mammalian red blood cells (RBC) from circulation. This hypothesis postulates the loss of sialic acid from RBC surface in two forms: (a) as vesicles containing the sialoglycoprotein glycophorin, and (b) as free sialic acid residues from glycophorin molecules remaining on cell surface. In this report we demonstrate the applicability of flow cytometric procedures to explore, at the cellular level, time-dependent changes on RBC surface with change in cell size, and with in vivo age. The RBC are probed with fluorescein isothiocyanate (FITC) labelled lectins and goat anti-human-IgG and -IgM. The relative intensity of fluorescence is correlated to the change in RBC size as measured by forward lightscatter. Reactivity of RBC with FITC-labelled wheat germ agglutinin can be inhibited with either 0.2M N-acetylglucosamine or by removal of sialic acid residues with neuraminidase. The properties of the smallest RBC correspond to those of the oldest RBC in their: (a) decreased reactivity with FITC-labelled lectins that recognize sialic acid residues, wheat germ and Limax flavus agglutinins, and (b) increased reactivity with FITC-labelled goat anti-human-IgG and -IgM. These results are compatible with our glycophorin hypothesis. Moreover, they suggest that the initial loss of sialic acid as glycophorin containing vesicles is gradual, while the subsequent step involving the loss of sialic acid residues is rapid and exposes multiple disaccharide galactose beta(1-3)N-acetylgalacosaminyl residues. These unmasked disaccharide sites are recognized by autoimmune IgG, IgM, and lectin-like receptors on macrophages resulting in the clearance of senescent RBC from circulation.

Susceptibility of glucose-6-phosphate dehydrogenase deficient red cells to primaquine, primaquine enantiomers, and its two putative metabolites. II. Effect on red blood cell membrane, lipid peroxidation, MC-540 staining, and scanning electron microscopic studies

The effects of primaquine (PQ), its enantiomers [(+)PQ,(-)PQ] and hydroxy metabolites [5-hydroxyprimaquine (5HPQ) and 6-desmethyl-5-hydroxyprimaquine (6D5HPQ)] on cell membranes of glucose-6-phosphate dehydrogenase (G-6-PD) deficient red cells were studied in vitro. There was no significant effect of PQ on the malonyldialdehyde (MDA) content of normal and heterozygous red cells, but it caused a significant increase in MDA in G-6-PD deficient red cells (P less than 0.05). There was no noticeable difference between the effects of the two enantiomers on this variable (P greater than 0.05). Compared to PQ, the hydroxy metabolites produced a significantly greater increase in MDA in all the groups studied (P less than 0.001). Of the two hydroxy metabolites, 6D5HPQ was more toxic than 5HPQ. Staining with MC540 showed that exposure to PQ, its enantiomers and two putative metabolites produced significant fluorescence, indicating that the drug produces marked alterations in membrane fluidity. Although the fluorescence was seen both in normal and heterozygous cells, the effect was marked in hemizygous deficient red cells (P less than 0.001). Scanning electron microscopic (SEM) studies revealed that PQ enantiomers had a stomatocytic effect on red cells of normal, heterozygous and hemizygous G-6-PD deficient red cells, whereas the putative metabolites had an echinocytic effect. The effects were most pronounced in G-6-PD deficient red cells.

Evidence for oxidative damage to red blood cells in mice induced by arsine gas

In animals and human beings exposed to arsine gas (AsH3) a severe and fulminant lysis of erythrocytes occurs. Little is known about the effects of subchronic exposure on the hematopoietic system or about the mechanism of hemolysis produced by arsine gas. To examine these, we exposed male and female mice to 0.000, 0.025, 0.500 and 2.500 ppm arsine gas for 6 h a day, 5 days a week during a 90-day period. After 5, 15, and 90 days of exposure, blood was collected and routine hematologic profiles were performed to document the effects of arsine gas on peripheral blood. A moderate hemolytic anemia, indicated by decreases in erythrocyte counts, hematocrits, hemoglobin concentrations and increases in mean corpuscular hemoglobins and mean corpuscular hemoglobin concentrations, was seen in blood samples collected after 5 days of exposure. In blood collected after 15 and 90 days of exposure, the anemia was less severe but a greater increase in mean corpuscular volumes and absolute reticulocyte counts revealed an active regenerative response. Higher concentrations of methemoglobin in animals in the 2.500 ppm exposure group (measured after 90 days of exposure) indicated that the rate of oxidation of heme (ferrous to ferric) increased due to exposure to arsine gas. Additionally, the presence of Heinz bodies in blood smears stained with brilliant cresyl blue and decreases in reduced glutathione concentrations in red blood cells exposed to arsine gas in vitro provide evidence that the mechanism of hemolysis involves depletion of intracellular reduced glutathione resulting in an oxidation of sulfhydryl groups in hemoglobin and possibly red cell membranes.

Studies in red blood cell preservation. 1. Effect of the other formed elements

The purpose of this study was to determine if the removal of most of the leukocytes and platelets would affect the in vitro characteristics of stored red blood cells (RBC). Fresh RBC concentrates prepared by removing platelet-rich plasma and filtration through Imugard IG 500 filters were compared with unmanipulated units after storage for up to 56 days. The filtered units were significantly better after 56 days storage for supernatant K+ (p = 0.001), hemolysis (p = 0.05), total vesicle membrane protein shed (p = 0.03), and RBC morphology score (p = 0.04). These differences occurred even though ATP levels were well maintained in both groups. The measurements that did not differ significantly were pH, hematocrit, ATP, 2,3-DPG, glucose and supernatant Na+. It is suggested that enzymes, leukotrienes, catecholamines and eicosanoids released by degenerating leukocytes and platelets may be inimical to RBC. Some may act as agonists on alpha-adrenergic and cholinergic muscarinic receptors present on RBC membranes.

Studies in red blood cell preservation. 2. Comparison of vesicle formation, morphology, and membrane lipids during storage in AS-1 and CPDA-1

The changes in morphology, the quantitative changes in membrane lipids and the shedding of exocytic vesicles by red blood cells (RBC) stored for 42 and 56 days in AS-1 and CPDA-1 were compared. RBC stored in AS-1 shed significantly less vesicle membrane cholesterol, phospholipid and protein and maintained better morphology scores. RBC membrane cholesterol remained higher after 56 days in AS-1 than in CPDA-1. The data suggest that during the first weeks of storage cholesterol is lost from the RBC membrane followed by a larger release of phospholipids accompanied by alterations in the phosphoinositides. The shedding of exocytic vesicles appears to be secondary to the changes in morphology resulting from the perturbation of the membrane lipids.

Ultrastructural changes in renal tubules associated with glomerular bleeding

Renal biopsies from ten patients presenting with macroscopic or heavy microscopic hematuria, shown to be glomerular in origin, were examined by light and electron microscopy. All biopsies showed erythrocytes within tubules by light microscopy and, in five cases, there were morphologic features of acute tubular necrosis. In four biopsies there was clear evidence by electron microscopy of uptake of erythrocytes by renal tubular epithelial cells, associated with some blunting of epithelial microvilli, vacuolar change and increased lysosomal content. Associated with erythrophagocytosis, the subsequent pathway of erythrocyte destruction within renal tubular epithelial cells closely resembled the hemolytic pathway described in macrophages of the reticuloendothelial system.

Effect of red cell age on vesiculation in vitro

Microvesiculation of RBC occurs in vivo and during in vitro storage. Vesiculation of young and old populations of RBC was measured under blood bank conditions. The RBC in whole units of blood were divided by density into two approximately equal fractions in a closed system. After storage for 35 d the haemoglobin-containing vesicles were quantitatively recovered. Quantitation of protein, cholesterol and phospholipids showed significantly larger amounts in the vesicles shed by the younger RBC. Otherwise vesicles shed by the two populations of RBC did not differ.

Molecular defect in the membrane skeleton of blood bank-stored red cells. Abnormal spectrin-protein 4.1-actin complex formation

During liquid preservation under blood bank conditions, red cell membranes inexorably undergo damage that decreases erythrocyte survival after transfusion. Accordingly, we have surveyed membrane skeletal protein interactions during storage. We uncovered a decrease in the in vitro formation of spectrin-actin complex in the absence (50%) or presence (60%) of protein 4.1. Actual formation of the spectrin-actin-protein 4.1 complex fell in a linear fashion during the storage period. This fall in spectrin-actin interaction tightly correlated with the decline in total red cell phospholipid (R = 0.9932) measured simultaneously. This decrement of spectrin-actin association could be restored to greater than 70% of normal values by preincubation of stored spectrin with 50 mM dithiothreitol. This storage injury to spectrin-actin interaction might weaken the membrane skeleton and lead to decreased red cell survival. In vitro reversibility of the damage by reducing agents suggests a possible new direction for prolonging the shelf life of stored blood.

Effects of nine synthetic putative metabolites of primaquine on activity of the hexose monophosphate shunt in intact human red blood cells in vitro

Suspensions of washed human red blood cells were treated with nine synthetic putative metabolic derivatives of primaquine (PQ'), and their individual effects on activity of the hexose monophosphate shunt (HMS) were quantitated by radiometric analysis of 14CO2 from [14C] glucose. The most potent HMS stimulant was 5-hydroxy-6-methoxy-8-aminoquinoline (5H6MQ), which caused 10-fold elevation of HMS activity at an estimated concentration of 0.004 mM. Ten millimolar primaquine (PQ) was required to achieve the same effect. Thus, 5H6MQ was approximately 2500-fold more reactive with the HMS than PQ. Other analogs achieved less than 0.4- to 154-fold increases in HMS reactivity. Patterns of effects on HMS activity indicated that 5-hydroxylation and/or N-dealkylation of PQ strongly enhanced HMS reactivity. In contrast, none of the putative metabolites of PQ activated the proteolytic system known to degrade oxidized protein in red cells, indicating that stimulation of the HMS by the PQ analogs was not related to an injurious oxidative stress. Red cells pretreated with 1.0 mM N-ethylmaleimide (NEM) or with 1.0% (w/v) sodium nitrite to cause glutathione sulfhydryl blockage and conversion of red cell hemoglobin to methemoglobin (metHb), respectively, also showed elevation of HMS activity when exposed to 5H6MQ. These observations suggested that 5H6MQ-induced elevation of HMS activity was at least partially independent of glutathione redox reactions, hydrogen peroxide accumulation and reaction with oxyhemoglobin. The relevance of these observations to proposed mechanisms of hemolytic toxicity of PQ is discussed.

Aged human erythrocytes exhibit increased anion exchange

Young and old erythrocytes show different rate constants of anion exchange as measured by 35SO4(2-) efflux at 37 degrees C. Results indicate that the rate constant for 35SO4(2-) efflux (SO2-4-Cl- exchange) from old cells is approximately 20% greater than from young less dense cells. The cell water volume of older cells is also decreased. Based on these results and previously reported decreases of cell membrane area in aged cells we conclude that anion exchange (35SO4(2-)) is increased in older, more dense human erythrocytes.

Changes of cell shape and surface charge topography in ATP-depleted human red blood cells

ATP depletion crenates human red blood cells. With ferritin-avidin (FA) and cationized ferritin (CF) cell surface labeling, it is demonstrated that the discocyte----crenated shape transformation alters the two-dimensional topography of negative charge sites. With restoration of ATP levels, cell shape and charge topography return to normal. Concurrent changes in red cell shape and surface charge topography can be explained by associations between membrane integral proteins and the red cell cytoskeleton.

Properties and characterization of vesicles released by young and old human red cells

We have presently demonstrated morphologic differences between young and senescent red cells following 18 h of metabolic depletion in vitro. Young and old red cells both form echinocytes, whereas only young cells demonstrated myelin forms or microspheres. Furthermore, vesicles were released in greater quantities into the cell-free supernatant from young cells. Isolated vesicles from both young and old red cells contained lipids, intrinsic membrane proteins (especially band 3), and haemoglobin, and they were also enriched in acetylcholinesterase (AChE). Young cells produced more vesicles than old cells but the composition of the low density vesicles was similar except that haemoglobin-spectrin complex was found exclusively in vesicles from young cells. Oxidation of young red cells prior to metabolic depletion prevented both myelin formation and vesicle release.

Osmotic fragility of drug carrier erythrocytes

Erythrocytes have been proposed as biogradable cellular carriers for drugs. Potentials of this therapeutic approach are organ-specific targeting, protection and prolonged in vivo function of the encapsulated drugs. Previous studies demonstrated the advantage of a hypo-osmotic dialysis procedure for macromolecule loading resulting in cells that are closely similar to normal erythrocytes. Osmotic fragility of unloaded and loaded "carrier" erythrocytes was studied both in respect of shelf-life and in vivo survival. Sudden haemolysis which is characteristic for normal erythrocytes was never obtained with carrier erythrocytes. Haemolysis appeared at all osmotic pressures and increased stepwise indicating the existence of various cell populations. However, the majority of cells were haemolysed at lower values of the osmotic fragility curve. Osmotic fragility was highly increased when cytotoxic chemotherapeutics were encapsulated, and these cells appeared as spherocytes using scanning electron microscopy. Osmotic fragility proved to be a simple but reliable method for the in vitro evaluation of carrier erythrocytes and the effect of the encapsulated substances.

Membrane cross bonding in red cells in favic crisis: a missing link in the mechanism of extravascular haemolysis

Red cells of G6PD (D-glucose-6-phosphate:NADP+ 1-oxidoreductase; G6PD) deficient (Mediterranean variant) subjects were studied during a fava bean haemolytic crisis. Two representative cases are described. In Case 1, haemolysis was still going on. In more than 50% of the red cells the Hb was confined to one part of the cell, leaving the other part as transparent as a Hb-free ghost. In this part the membranes appeared tightly bonded because swelling did not peel apart the bonded membrane areas. This feature is defined as membrane cross bonding (MCB). In Case 2, haemolysis had terminated and MCB-cells were less than 1%. MCB was reproduced in vitro by incubating G6PD-deficient whole blood with 1 mM divicine for up to 10 h. Subsequent shrinkage of red cells in hypertonic plasma (400 mOsm) resulted in the rapid formation of MCB. Membrane modifications by divicine, contained in fava beans, followed by osmotic shrinkage in the kidney and/or squeezing in the microcirculation are proposed as the cause of MCB during the favic crisis. MCB reduces the effective surface area of red cells. This is a plausible cause for sequestration by the reticulo-endothelial system. Intravascular haemolysis observed in favic crisis cannot be explained by mechanical forces, but it is possible that the effective surface area is reduced by MCB to such an extent that red cells lyse osmotically.

Erythrocyte membrane vesiculation and changes in membrane composition during storage in citrate-phosphate-dextrose-adenine-1

Serial studies were made of the membranes of the erythrocytes and the vesicles shed during storage of blood in polyvinyl chloride containers for 35 days in citrate-phosphate-dextrose-adenine anticoagulant. Special precautions were taken to eliminate artifacts created by contaminating leukocytes, platelets and red blood cell ghosts. A total of 15.6% of the cholesterol and 5.2% of the phospholipids of the membranes was lost with no gross change in the gel electrophoretic patterns. The quantity of vesicles found in the supernatant plasma increased during storage and their membranes were characterized by the absence of spectrin, ankyrin, and periodic acid Schiff bands 2 and 3. The ratio of lipids to protein in the vesicles increased as they accumulated perhaps reflecting a rearrangement of the erythrocyte membrane constituents during prolonged maintenance at 4 degrees C.

Lipid peroxidation in rabbit reticulocytes

Lipid peroxides in rabbit erythrocytes and plasma were determined while anemia was induced by daily bleeding. They increased as reticulocytes increased and returned to normal with the morphological transformation to mature cells.

Binding of autologous IgG to human red blood cells before and after ATP-depletion. Selective exposure of binding sites (autoantigens) on spectrin-free vesicles

Binding of autologous IgG to fresh, ATP-depleted red blood cells as well as to spectrin-free vesicles was studied by a non-equilibrium binding assay using 125I-iodinated protein A from Staphylococcus aureus. IgG binding was 14-times higher to spectrin-free vesicles than to ATP-maintaining red blood cells and 4-times higher than to ATP-depleted erythrocytes from which these vesicles were released. Protein A binding to vesicles that were released from washed and nutrient-deprived erythrocytes, was dependent on added autologous IgG. However, spectrin-free vesicles that were spontaneously released from erythrocytes conserved in whole blood, bound similar amounts of protein A with or without added autologous IgG (0.45-0.55 ng/micrograms band 3 protein). These findings demonstrate that opsonization of spectrin-free vesicles by autologous IgG occurs not only in the test tube, but also under blood blank conditions. The binding characteristics of IgG to spectrin-free vesicles are indicative of a natural autoantibody rather than an unspecific binding of autologous IgG. The preferential binding of IgG to spectrin-free vesicles implies a selective exposure of corresponding autoantigens in membrane regions that have lost cytoskeletal anchorage and bud off.

Aging of the erythrocyte. XIV. ATP content does decrease

ATP content shows a cell-age dependent decrease in bovine erythrocytes separated according to Murphy. An important point in the evaluation of results lies in considering differences in the ATP consumption between cells of various age during separation. The decrease in ATP occurs in spite of diminished ATPase activity in older cells.

The rate of osmotic hemolysis: a relationship with membrane bilayer fluidity

A first-order semilogarithmic plot of the decrease in turbidity that takes place during hemolysis is used to define an apparent rate of hemolysis. The effect on this rate of hemolysis of various membrane modifications is studied. Triton X-100, ethanol and chlorpromazine, which dissolve into the membrane, all increase the rate of hemolysis, even though the same concentration of ethanol and chlorpromazine has been shown to decrease the osmotic fragility. Glutaraldehyde, azodicarboxylic acid-bisdimethylamide (diamide) and intracellular Ca2+ are used to produce cross-links on membrane proteins. All of these reagents decrease cell deformability but have different effects on the rate of hemolysis, with Ca2+ increasing, glutaraldehyde decreasing and diamide producing almost no effect on the rate. These modifications are also found to alter the ESR spectra of the stearic acid spin-label, 2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxyl, which probes mobility in the hydrophobic core of the lipid bilayer. A correlation between the effect of membrane modifications on bilayer fluidity and the rate of hemolysis suggests that the rate-limiting process which determines the rate of hemolysis involves rupturing of the bilayer.

Red cell fragmentation in the dog: an editorial review

Red blood cell fragments in blood smears from dogs are described morphologically and pathogenetically. Categories include microangiopathic fragmentation, spherocytic fragmentation. Heinz body fragmentation, metabolic fragmentation associated with systemic disease, and artifactual fragmentation. Microangiopathic fragmentation is associated with direct physical damage to normal circulating red blood cells as they pass through abnormal capillary beds. Spherocytic fragmentation is a common feature of immune-mediated hemolytic anemia and results from the removal of portions of antibody-coated erythrocyte plasma membranes by phagocytes of the reticuloendothelial system. Heinz body fragmentation occurs when rigid particles of oxidized hemoglobin are torn from affected red cells as they circulate through the spleen. Metabolic fragmentation is an ill-defined syndrome most commonly associated with cholesterol loading of red cell membranes caused by lipid metabolism abnormalities. Resulting spiculated red cells are more susceptible to traumatic disruption. All the types of red cell fragmentation described in dogs have been observed and documented in man.

Aging of the erythrocyte. IV. Spin-label studies of membrane lipids, proteins and permeability

Spin-label studies demonstrated age-related alterations of the erythrocyte membrane concerning both lipid and protein components. Decrease in fluidity of membrane lipids correlated with decreased membrane permeability to a hydrophobic spin label TEMPO, permeability to a more hydrophilic TEMPOL being less affected. The rigidification of membrane lipids was much more pronounced in whole membranes than in liposomes composed of membrane lipids, suggesting changes in lipid-protein interactions as an important factor in the decrease of lipid fluidity in aged red cells. ESR spectra of membrane-bound maleimide spin label evidenced alterations in the state of membrane proteins during cell aging in vivo.

Erythrocytes as carriers of chemotherapeutic agents for targeting the reticuloendothelial system

The object of this work was to define a model using hypotonically loaded erythrocytes as a vehicle to target drugs to the reticuloendothelial system (RES). The optimum hemolytic event was found to occur at 100 mOsm/kg using a 0.5-min exposure at 0 degrees C. Approximately one third of the total volume of the cells could be replaced with hypotonic drug solutions under these conditions. Although cytosine-beta-D-arabinofuranoside, ara C, is membrane permeable and could not be entrapped in the erythrocytes, phosphorylation of this nucleoside antimetabolite enabled it to be loaded efficiently. Actinomycin D could be loaded and retained within the cells at 0 degrees C, but 90% of this loaded drug leaked out of the erythrocytes in 1 min at 37 degrees C. Actinomycin D-DNA complexes, however, could be loaded and retained for longer periods. In this case, 50% of the DNA-bound drug was retained in the cells for one hour at 37 degrees C. It was found that the glycopeptide antitumor antibiotic, bleomycin, could be entrapped and retained in the cells without appreciable leakage. It was possible to load a human therapeutic dose of this drug in 1-2 ml of packed cells. Furthermore, it was demonstrated that bleomycin entrapped in erythrocytes was significantly more effective than the same dose of free drug in suppressing the phagocytic function of the RES in Balb/C and C3H mice. The rationale is discussed for the possible use of these drugs, entrapped in erythrocytes, for the production of RES blockade in the treatment of disorders in man.

Is "deformability" a parameter for the rate of elimination of erythrocytes from the circulation?

The "deformability" of rat erythrocytes can be gradually decreased by an in vitro treatment with the SH-oxidizing agent diamide. Despite of this reduced deformability the cells are retained in the circulation for many hours when reinfused into the rat. Cells rigidified with glutaraldehyde are even less deformable than diamide treated cells, but also survive for many hours. In contrast to rigidified cells of normal volumes swollen rigidified cells obtained by a heat treatment of erythrocytes are rapidly eliminated. The results support the notion that the "recognition" preceding the elimination of senescent and damaged cells of normal volumes by the reticulo-endothelial system is not solely based on their diminished deformability.