Membrane Abnormalities of Pyruvate Kinase Deficient Red Cells

Two experimental systems have been applied to the study of PK-deficient red cells in an attempt to reveal possible membrane abnormalities of these erythrocytes: (1) the glycoprotein self-digestion of intact erythrocytes during in vitro incubation at 37 degrees C; (2) the red cell sensitivity to the lytic action of mouse macrophages. PK-deficient erythrocytes display a more precocious than normal membrane glycoprotein self-digestion and are much more susceptible than normal to the cytotoxic activity of mouse macrophages. This latter effect is more pronounced in young than in old PK-deficient red cells. These observations indicate the existence of membrane abnormality in PK-deficient red cells other than those so far suspected.     

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

S ummary 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.     

Calpain (Ca(2+)-dependent thiol protease) in erythrocytes of young and old individuals.

Limited proteolysis by calpain (Ca(2+)-activated protease; EC 3.4.22.17) is believed to regulate the function of membrane enzymes and modify the behavior of membrane structural proteins. Calpain is activated by autolysis. The degradation of band 3 protein by mu-calpain is known to be enhanced in erythrocyte membranes from human individuals > 70 years old (old) as compared with that from individuals 20-30 years old (young). In the present study, monoclonal antibody to mu-calpain was used to study the behavior of calpain in erythrocytes of young and old individuals. Less calpain was found in erythrocyte cytosol and membranes from old than in those from young. Increasing the erythrocyte Ca2+ induced translocation of calpain to the cell membrane and autolysis of the enzyme. Alkylation of erythrocyte thiols also promoted translocation of calpain to the membrane, especially in the presence of Ca2+. When calpain was added to erythrocyte membranes, initial binding was greater and subsequent autolysis faster in old than in young individuals, possibly arising from alterations in cell membranes of old individuals. The enhanced calpain autolysis was accompanied by enhanced degradation of band 3 protein in the old. The results suggest that calpain in old individuals is translocated to the cell membrane and is activated by autolysis, resulting in degradation of certain membrane proteins and loss of calpain. Enhanced calpain-induced membrane proteolysis may play a role in abnormal cell destruction (e.g., shortening the life span of erythrocytes in the aged, neuronal degeneration, etc). The erythrocyte membrane provides a convenient model for the study of age-associated alterations in cell membranes and in calpain behavior.     

Superoxide radical production after phorbol ester stimulation in neutrophils of aged donors

Superoxide anion radical production was studied in purified neutrophils of young and old donors after stimulation with phorbol 12-myristate 13-acetate to determine whether phorbol-stimulated activation of NADPH-oxidase was altered by aging. Superoxide radical production of neutrophils of healthy ambulatory edlerly (mean age 73 years) was increased compared to young adult controls. Expressed as nmol superoxide/min/mg protein, however, old cells were no different from young. Neutrophils of the edlerly contained nearly 20% more protein/cell than young cells, yet neutrophil diameter and volume were not increased in the old cells. Binding affinity and maximum binding capacity of ³H-phorbol 12,13-dibutyrate were similar in young and old neutrophils. Maximum binding capacity was similar whether expressed on a per cell or per mg protein basis. Although others have suggested that initial plasma membrane events leading to superoxide radical production are diminished in aging cells, these studies show that intracellular phases of the mechanisms leading to superoxide radical production are maintained. Superoxide production rate per cell is increased in older persons, associated with a higher protein content per cell but not larger cell size.     

Drug-induced endocytosis of neonatal erythrocytes

The erythrocytes of the newborn infant have many properties that distinguish them from those of adults, and their membranes are also different from those of adult erythrocytes. We compared the ability of adult and neonatal RBCs to undergo endocytosis on exposure to drugs. Using a quantitative method, we showed that neonatal erythrocytes undergo a greater degree of endocytosis than do adult RBCs in response to primaquine, vinblastine, and chlorpromazine, and are sensitive to lower concentrations of the drugs. Some forms of drug-induced endocytosis are red cell age-dependent; when RBCs were separated by density gradient centrifugation, the membranes of the younger, less dense populations of both the neonatal and adult RBCs were capable of more extensive internalization than those of the denser, older RBCs. Neonatal RBCs of a given density undergo more endocytosis than do adult RBCs of the same density, suggesting that the membrane of the neonatal RBC is less stable and capable of more of the reorganization reflected in endocytosis than is the adult RBC membrane.     

The "stomatin" gene and protein in overhydrated hereditary stomatocytosis

In overhydrated hereditary stomatocytosis (OHSt), Coomassie- and silver-stained polyacrylamide gels show an apparently complete deficit of the 32-kDa membrane protein, stomatin. We have used an antistomatin antibody to examine peripheral blood films, bone marrow, splenic tissue, and hepatic tissue from these patients by immunocytochemistry. This technique revealed that, in fact, some red cells did show positive stomatin immunoreactivity; and consistent with this result, Western blot analysis of the red cell membranes confirmed that about one twentieth to one fiftieth of the normal amount of stomatin was in fact present. Flow cytometry, combining immunoreactive quantitation of stomatin expression with thiazole orange staining for reticulocytes, showed that in OHSt, it was the young cells that had more stomatin. Magnetic-activated cell separation studies, using beads to which an anti-transferrin receptor antibody was conjugated, confirmed that in OHSt there was a correspondence between expression of stomatin and the transferrin receptor. Immunocytochemistry and Western blotting revealed that in OHSt patients, the protein was present in spleen, liver, neutrophils, platelets, monocytes, and about 50% of the peripheral lymphocytes, with the same distribution as in healthy controls. Neither Southern blots, nor direct sequencing of multiple subclones of the cDNA, nor sequencing of amplicons from genomic DNA revealed any significant abnormality in stomatin gene sequence in these patients. The deficiency of stomatin from red cells appears to be due to a loss of stomatin from these red cells on maturation in the bone marrow and in the circulation.     

Stored red‐blood‐cells inhibit platelet function under physiologic flow

Background and Objectives The DiaMed Impact R tests platelet function under close to physiological flow conditions. The machine is designed to use whole blood but by adding back compatible red cells, it can be used to study stored platelet concentrates. To date, red cells ≤14 days old have been used. In this study, the effect on the assay of using red cells stored for up to 60 days was examined. Material and Methods This study looked at buffy coat‐derived platelet concentrates on day 2 of storage along with various stored red‐blood‐cells (RBC). To determine whether the age of the RBC is a factor in supporting adhesion and aggregation, platelets were assayed with either RBC stored between 2 and 60 days or with separated ‘young’ and ‘old’ red cell populations obtained using a centrifugation method and confirmed by percoll gradient analysis. Results A statistically significant difference was observed between red‐blood‐cells stored for ≤20 days compared with those which have been stored for 21–60 days in respect of their ability to support platelet adhesion (SC) and aggregation (AS) (P < 0·01). Separating red cells by centrifugation into top (young population) and bottom (old population) showed that the effect of storage was much greater than was any difference between young and old at the individual time‐points e.g. ‘young’ red cells from stored units were poorer at supporting platelet adhesion and aggregation than ‘young’ red cells from fresh units. Conclusion Results suggest that the red cells should be stored for less than 21 days when using this assay. This assay may also allow assessment of red cell functionality.     

Plasma lipids and composition of red cells in four cases of Werner's syndrome

Four cases of accelerated aging, known as Werner's syndrome (WS), are presented. Plasma lipid and lipoprotein findings and lipid compositions of red cell membranes are compared to those of old and young healthy people. Typical clinical findings, as reported in the literature, confirmed the diagnosis. Furthermore, an elevated osmotic fragility of red blood cells (RBC) was observed. RBC membranes of WS patients showed phospholipid concentrations similar to those found in people aged over 70 years, which have been reported to be lower than those of mature donors aged below 30 years. Fatty acid patterns of RBC membranes and plasma phospholipids were indicative of some disturbance in phospholipid subclass distributions in WS-patients.     

Some characteristics of the human erythrocyte as a function of donor and cell age

Erythrocytes from healthy human donors of various ages (18-93 years) were separated on Percoll into four density fractions. Increased cell density has been reported to correlate with the age of the erythrocyte. Aged individuals, while having normal hematocrits, show an increased percentage of low-density young erythrocytes and almost twice as many reticulocytes in their circulation as do young adults. This evidence for increased, well-compensated, red cell turnover in elderly humans is supported by the finding in older individuals of increased levels of erythrocytes bearing autologous IgG on their membranes. Using fluorescent anti-IgG, erythrocytes with bound autologous IgG could be found in all density fractions from donors of all age groups. The old donors had an increased number of fluorescent cells that appeared in all density fractions albeit with a definite skewing toward the more dense cell fractions. Erythrocytes from young donors had higher levels of intact hemoglobin per cell than those from old donors. The relevance of these results to the aging process and the ability of senescing individuals to withstand hematologic stress are discussed.     

Moving Boundary Electrophoresis and Sialic Acid Content of Normal and Polycythaemic Red Blood Cells

S ummary. Moving boundary electrophoresis has been used for the assessment of the negative charge on erythrocyte membranes. The equipment is easy to construct and simpler to use than the microelectrophoresis technique. There is a direct relationship between the electrophoretic velocity measured by the moving boundary method and the sialic acid content of the red cell membrane. Polycythaemic erythrocytes have a higher electrophoretic mobility and higher sialic acid content than normals.
Separation of the erythrocytes according to their densities shows that old polycythaemic erythrocytes have a higher electrophoretic mobility and sialic acid content than young normal ones. This suggests that the difference is not associated with a younger erythrocyte population in polycythaemia vera, but may represent a membrane change in the abnormal erythroid clone present in this disease.     

Effects of aging on atrial and ventricular human myosin

Enzymatic and structural studies of human cardiac myosin from young and old subjects have been investigated to determine possible changes in myosin properties in aging hearts. Human ventricular myosin from old subjects (47-70 years old) has lower actin-activated ATPase activity than and increased alkaline sensitivity as compared to myosin from young subjects (1-132 months old). Ca2+-and K+(EDTA)-ATPase activities, pyrophosphate gel patterns and one-dimensional peptide mapping of heavy chains of ventricular myosin from old subjects are similar to those observed for myosin from young subjects. Atrial myosin from human hearts differs significantly from ventricular myosin in that the Ca2+-, Mg2+- and actin-activated myosin Mg2+-ATPase activities of atrial myosin are significantly higher than those of ventricular myosin. Pyrophosphate gel electrophoresis patterns and peptide mapping of heavy chains of atrial myosin are also different from those of ventricular myosin. Unlike ventricular myosin, atrial myosin from young hearts is similar to that of atrial myosin from old hearts in its enzymatic and structural properties.     

Red cell diphosphoglycerate mutase. Immunochemical studies in vertebrate red cells, including a human variant lacking 2,3-DPG.

Diphosphoglycerate mutase (DPGM) was purified to homogeneity from human erythrocytes. The enzyme and Freund adjuvant were injected into chickens and yielded a monospecific precipitating antibody. Radial immunodiffusion with this antibody was used to measure the amount of DPGM in hemolysates from human adult and cord red cells. Dog, rabbit, rat, chicken, and goat red cells all had DPGM during the neonatal period, but goat adult red cells had no detectable enzyme. Single bands with no spurs were present on Ouchterlony plates in which human hemolysate was placed adjacent to hemolysates from the other species tested. The amount of human red cell DPGM did not differ between young and old cells separated by centrifugation. Red cells from a patient with a DPGM genetic variant who had erythrocytosis and no detectable enzyme activity contained a reduced amount of DPGM as determined by radial immunodiffusion. The abnormal DPGM differed from normal by immunoelectrophoresis and in stability as measured by the amount of crossreacting material in young versus old erythrocytes.     

In Vitro Studies of Red Cell Metabolism in Haemoglobin H Disease

S ummary . A study has been made of glycolysis and some membrane abnormalities in the red cells of six patients with haemoglobin H disease. Haemoglobin H has been shown to be thermolabile and this property was used to determine the amount present in blood samples. Fresh red cells have increased anaerobic glycolysis and hexose monophosphate pathway activity in accord with the low MCHC of the cells and the young red cell population present in blood samples. However, red cell ATP was low in three of four patients studied and GSH was low in four of six patients. Red cell phospholipid was abnormally high in the four patients studied. Following incubation in vitro , red cell phospholipid, AChE activity, ATP and GSH decreased in an abnormal manner not attributable to the abnormal degree of lysis that occurred. Studies with young and old red cell fractions indicated that whilst GSH was significantly low in older cells hexose monophosphate pathway activity tended to be high. The significance of these results is discussed     

Age and features of insulin reception by the plasma membranes of liver cells

The specific binding of 125I-insulin by liver cell plasmatic membranes of rats aged 5-6 mos. and 24-26 mos. was studied. A decrease in hormone binding with the receptors of old animals as compared to young ones in the presence of similar concentration of immunoreactive insulin in the blood was established. A graphical analysis of the data after Scatchard showed that an age-related decrease in 125I-insulin binding with rat liver cell plasmatic membranes resulted from the loss of binding sites in old rats as compared to young animals. The affinity of insulin receptors to the hormone did not change with age.     

Effects of deficiencies of glycophorins C and D on the physical properties of the red cell

S ummary Red cells of the rare Leach phenotype lack the membrane glycophorins C and D, and a proportion of the red cells are elliptocytes. Judging from tests on suspensions of red cell ghosts sheared rotationally in an ektacytometer, it has previously been suggested that these membranes are relatively fragile and poorly deformable. We have carried out analyses of individual red cells to investigate possible factors which underlie the physical changes in these glycophorin-deficient cells. Micropipette analysis of the red cell membrane showed that the rigidity and viscosity were normal, both for elliptocytes and discocytes, for three donors deficient in glycophorins C and D. Red cell transit times through 5 μ m pores, measured electronically for 2000 individual cells, showed no differences from controls. It was confirmed that the index of deformation obtained using an ektacytometer was reduced, but our results suggest that this arises from shape rather than membrane changes. The elliptocytes were found to have a lower volume and surface area than discocytes from the same donor (measured by micropipette aspiration of single red cells), and were rarely found in less dense red cell fractions. No reticulocytes were found to be elliptical. These data suggest that the elliptocytes are older red cells, and are formed from red cells which are initially released into the circulation with normal shape. Their elongated shape might arise from permanent distortion of the unstable membrane by shear forces in the circulation.     

Biochemical characterization of ventricular myosin from spontaneously hypertensive turkeys

Several stimuli are able to alter the synthesis of cardiac myosin isoenzymes. Particularly in the rat a shift toward a low-ATPase isomyosin is generally observed during development and in cardiac hypertrophy due to pressure overload. On the contrary in spontaneously hypertensive turkeys both ageing and the increasing degree of cardiac hypertrophy are accompanied by a different behaviour of ventricular myosin. In fact in a previous study we have shown that the Ca2+-activated ATPase activity of ventricular myosin increases about three folds from young normotensive to old hypertensive animals. Accordingly the peptide pattern obtained after chymotryptic digestion of myosin showed that some peptides, which are not evident or barely discernible in young animals, are present in the adult ones. In this study we compare the ventricular myosin from young normotensive and adult hypertensive turkeys with atrial myosin. The results obtained suggest that in the ventricles of hypertensive turkeys the synthesis of an isomyosin with biochemical properties close to those of atrial myosin occurs.     

Increased potassium transport and ouabain binding in human Rhnull red blood cells.

Potassium (K+) influx and 3H-ouabain binding were studied in human red cells completely lacking the rhesus (Rh) antigens (Rhnull cells) and compared with normal Rh(D) red cells. The Rhnull cells, originally described by Seidl, Spielmann, and Martin (Vox Sang. 23:182, 1972) were normal in size, cation, and water content, indicating no significant increase in cell volume as occurs in young human red cells. However, the ouabain-insensitive K+ permeability, as well as the ouabain sensitive active K+ transport, were increased 1.6 1.8-and 1.4-1.5-fold, respectively, above the values found in Rh(D) control cells. The Na+K+ ATPase activity of membranes from Rhnull cells was also higher than from Rh(D) cells. Binding studies with 3H-ouabain revealed that at 100% K+ pump inhibition Rhnull cells bound 670 and Rh(D) cells 450-500 ouabain molecules per cell. Since the rate of ouabain binding was identical in Rhnull and Rh(D) control cells, we concluded that the Rhnull cell had about 35%-45% more cation pumps than the Rh(D) cell. These additional pumps in Rhnull cells appeared to be indistinguishable from those in control cells. Anti-D or the serum from the Rhnull individual did not alter cation permeability in Rh(D) red cells. The data suggested that the Rhnull cell, known for its hematologic malfunction, was not a young or prematurely released red cell, but had a pleiotropic membrane defect which also affected the passive and active cation transport system on the molecular level. Our finding precludes a structural identity of the rhesus antigen with the molecules composing the Na+K+ pump system.     

Malaria and the red cell membrane

Malarial parasites are primarily parasites of red cells and during infection ingest most of the haemoglobin within these cells, leaving the membrane as the only vestige of the original host cell. The red cell membrane thus plays a key role at all stages of infection with malarial parasites, and is modified in many ways during parasitisation, so that at least functionally it has little resemblance to the membrane from which it was originally derived. The highly specific and ordered process of parasite invasion of red cells is regulated at least in part by the uninfected red cell membrane. The red cell sialoglycoproteins or glycophorins of this membrane have been shown to play an important role in invasion by Plasmodium falciparum, the species of most importance to man because of it's high morbidity and mortality. Structurally, dynamic changes occur within the membrane during parasitisation, and a number of parasite proteins have been found to be associated within it, but changes on the surface of the infected cell have been more difficult to demonstrate. The membrane of the infected cell is important in the many metabolic processes of the parasite, as well as the critical cell-cell interactions that occur when cells containing mature parasites bind to endothelial cells (cytoadherence), bind to uninfected cells (rosetting), or interact with macrophages and other leucocytes. The recognition molecules on the red cell membrane involved in invasion, cytoadherence and rosetting appear to be quite distinct. Structural and functional changes have also been shown to occur in the membranes of uninfected red cells, both in infected patients, and in the presence of parasites in vitro. Interactions of the parasite P. falciparum with the red cell membrane hold the key to our understanding of the pathogenesis of severe falciparum infection in man.     

The effect of antigen priming on immunological response regulation in aging.

The primary anti-sheep red blood cells response and the response of antigen primed CBA mice aged 3–29 months were compared. There was a 30-fold decline with age in the primary immunological response, tested by the direct plaque-forming cell number. In young and young adult mice, priming resulted in a fall of antibody production and of number of Ig-positve spleen lymphocytes. During the lifespan the response of primed mice increased, reaching and then exceeding the level of primary response in senescence as much as 20-fold. Negative correlation was established between antibody-forming and nuclear spleen cell numbers of old primed mice.The adoptive transfer of spleen cells of primed young adult mice suppressed the antibody production in immunized recipients, whereas that of old primed spleen cells produced no reaction, the response of the recipients of old primed spleen cells being thus higher.The addition of young bone marrow to old primed mice enhanced the response and abolished the negative correlation between plaque-forming cell and nuclear spleen cell numbers.The data obtained showed a decreased suppressor activity of the antigen primed spleen cells with aging. This phenomenon seems to reflect certain features of the immune response regulation in old age.     

Isolation of human platelet membrane microparticles from plasma and serum

Methods have been developed to isolate human platelet membrane fragments from plasma and serum. Rabbit antibody produced against the human platelet membrane glycoprotein complex, IIb/IIIa, was utilized in an immunoelectrophoretic assay to evaluate the amount of this antigen in various microparticle preparations. The serum concentration of platelet microparticles was more than tenfold greater than that observed for plasma (65 micrograms/ml versus 4.4 micrograms/ml, respectively). Ultrastructural evaluation of either plasma or serum- derived microparticles disclosed a variety of membrane fragments and membrane-bound vesicles with occasional fragments of red blood cells, white blood cells, and platelets. In contrast, microparticle preparations derived from isolated washed platelets after thrombin stimulation contained a heterogeneous array of membrane fragments, vesicles, and granules but no identifiable red cell, white cell, or platelet fragments. Thus, these studies demonstrate that normal human plasma and serum contain platelet membrane fragments that are produced during cell activation. If a similar loss of platelet membranes occurs in vivo following reversible platelet activation, it is possible that the resulting membrane modifications may be of importance in both the structural and functional changes that develop during platelet senescence.