Irreversible deformation of the spectrin-actin lattice in irreversibly sickled cells.

Irreversibly sickled cells (ISC's) are circulating erythrocytes in patients with sickle cell disease that retain a sickled shape even when oxygenated. Evidence points to a membrane defect that prevents the return of these cells to the normal biconcave shape. The erythrocyte membrane protein spectrin is believed to help control erythrocyte shape and deformability. Recent studies suggest that normally spectrin and an erythrocyte actin form a self-supporting, fibrillar, lattice-like network on the cytoplasmic membrane surface. When normal erythrocyte ghosts are extracted with Triton X-100 all the integral membrane proteins and most of the membrane lipids are removed, leaving a ghost-shaped residue composed principally of spectrin and actin. We concentrated ISC's from patients with sickle cell anemia and compared the morphology and protein composition of ghosts and Triton-extracted ghost residues prepared from these ISC's with similar preparations of reversibly sickable cells and normal cells. (a) Many ISC's formed ISC-shaped ghosts. (b) All ISC-shaped ghosts formed ISC-shaped Triton residues. (c) Spectrin, erythrocyte actin (Band 5), an unidentified Band 3 component, and Band 4.1 were the major protein components of the Triton residues. All membrane-associated sickle hemoglobin was removed by the Triton treatment. (d) No ISC-shaped ghosts or ISC-shaped Triton residues were formed when deoxygenated, sickled RSC's were lysed or Triton-extracted. ISC-shaped ghosts and Triton residues were never formed from normal cells. These observations suggest that a defect of the "spectrin-actin lattice" may be the primary abnormality of the ISC membrane. Since ISC's are rigid cells, the data support the postulate that spectrin is a major determinant of membrane deformability. Finally, they provide direct evidence that spectrin is important in determining erythrocyte shape.

Common structural polymorphisms in human erythrocyte spectrin.

Restricted tryptic digestion of erythrocyte spectrin at 4 degrees C followed by two-dimensional (isoelectric-focusing/sodium dodecyl sulfate) polyacrylamide electrophoresis yields highly reproducible maps of approximately 50 peptides with molecular weights between 80,000 and 12,000. Based on molecular weight and isoelectric point (pI), each unique alpha- and beta-subunit domain can be identified and compared with spectrin peptides from other individuals. The alpha-subunit of spectrin from 60 Caucasian donors contains a 46,000-mol-wt tryptic domain, called alpha II-T46, Type 1; more extensive tryptic digestion of this domain generates peptides with molecular weights of 35,000, 30,000, 25,000, and 16,000. Spectrin from 29 of 37 black donors representing 14 kindreds shows variation in the molecular weight and/or pI of peptides from the alpha II domain. In the most common form, Type 2, alpha II tryptic peptides are increased in molecular weight by 4,000, and the pI becomes more basic. Other alpha II variants are characterized by either the 4,000 increase in molecular weight (Type 3) or by the basic shift in pI (Type 4). When limit peptide maps of intermediate-sized tryptic and CNBr peptides from the alpha II-domain Types 1 and 2 are compared, a consistent alteration in the chromatographic mobility of one limit peptide is observed. Polymorphism in the alpha II subunit of spectrin did not itself produce anemia, nor did it appear to alter the expression of an underlying hereditary spherocytosis or elliptocytosis. In six family studies, the alpha II 46,000-mol-wt variations observed were consistent with Mendelian inheritance.

Molecular defect of spectrin in hereditary pyropoikilocytosis. Alterations in the trypsin-resistant domain involved in spectrin self-association.

In hereditary pyropoikilocytosis (HPP) the erythrocyte membrane skeleton exhibits mechanical instability that can be correlated to defective self-association of spectrin heterodimers. To detect structural changes in the functional domains of HPP spectrin we have examined the peptide pattern produced by limited tryptic digestion of spectrin extracts from two families that contain three HPP patients. Limited tryptic digestion of all three HPP patients revealed a similar and reproducible decrease in the staining intensity of an 80,000-, and 22,000-, and an 88,000-dalton polypeptide with a concomitant increase in a 74,000- and a 90,000-dalton polypeptide as compared with controls. Only changes in the 80,000-, and 74,000-, and 22,000-dalton polypeptides could be correlated to defective spectrin self-association and the amount of spectrin dimers in 0 degrees C extracts of the HPP patients and their affected kindred. Similar results were obtained when the tryptic digests were analyzed by two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the affected 74,000- and 80,000-dalton polypeptides focusing into multiple spots ranging in isoelectric point from 5.3-5.4. When HPP spectrin dimers and tetramers were separated and subjected to trypsin digestion, changes in the 80,000-, 74,000-, and 22,000-dalton polypeptides were found predominantly in the spectrin dimer pool. Similar results were obtained for spectrin from two of the probands' mother, whom we have identified as an HPP carrier. We conclude that these HPP patients contain a population of normal, (principally tetrameric) and mutant (principally dimeric) spectrin. The latter is characterized by a defective spectrin dimer self-association due to conformational changes that affect the 80,000-dalton domain.

Intracellular polymerization of sickle hemoglobin. Effects of cell heterogeneity.

To determine the extent to which the broad distribution in intracellular hemoglobin concentrations found in sickle erythrocytes affects the extent of intracellular polymerization of hemoglobin S, we have fractionated these cells by density using discontinuous Stractan gradients. The amount of polymer formed in the subpopulations was experimentally measured as a function of oxygen saturation using 13C nuclear magnetic resonance spectroscopy. The results for each subpopulation are in very good agreement with the theoretical predictions based on the current thermodynamic description for hemoglobin S gelation. We further demonstrate that the erythrocyte density profile for a single individual with sickle cell anemia can be used with the theory to predict the amount of polymer in unfractionated cells. We find that heterogeneity in intracellular hemoglobin concentration causes the critical oxygen saturation for formation of polymer to shift from 84 to greater than 90%; polymer is formed predominantly in the dense cells at the very high oxygen saturation values. The existence of polymer at arterial oxygen saturation values has significance for understanding the pathophysiology of sickle cell anemia. The utility of these techniques for assessing various therapeutic strategies is discussed.

Abnormal redox status of membrane-protein thiols in sickle erythrocytes.

Although sickle erythrocytes (RBC) undergo excessive autooxidation, investigators have not found evidence for abnormal oxidation of protein thiols in sickle RBC membranes (e.g., protein aggregates linked by intermolecular disulfide bonds). However, the conventional techniques heretofore used cannot detect more subtle changes in thiol status such as abnormal intramolecular disulfide bonds. We examined RBC membranes using thiol-disulfide exchange chromatography which partitions sodium dodecyl sulfate-solubilized proteins on the basis of reactive thiols, yielding gel-bound (reduced-thiol) and filtrate (oxidized/blocked-thiol) fractions. Membranes from normal RBC partition so that only 13.6 +/- 1.4% of all membrane protein is found in the filtrate fraction. An abnormally increased amount of membrane protein from sickle RBC (21.5 +/- 4.3%) partitions into the filtrate fraction (P less than 0.001). Since sickle RBC do not have high molecular weight aggregates of membrane protein, this indicates abnormal intramolecular thiol oxidation in sickle RBC membranes. Treatment of normal RBC with thiol blockers and oxidants simulates this shift of membrane protein into the filtrate fraction. Analysis using polyacrylamide gel electrophoresis reveals that the filtrate fraction derived from normal RBC consists mostly of band 7 and glycophorins, with only trace amounts of other membrane proteins. Superimposed upon this normal background, sickle RBC filtrates are enriched with all proteins (including cytoskeletal protein bands 1, 2, 2.1, and 4.1), suggesting a generalized oxidative perturbation of sickle RBC membranes. These observations support the concept that excessive RBC autooxidation may play a role in sickle disease pathophysiology, and they perhaps help explain the development of those membrane abnormalities that may reflect cytoskeletal dysfunction in sickle erythrocytes.

Single cell laser light scattering spectroscopy in a flow cell: repeated sickling of sickle red blood cells.

We performed dynamic laser light scattering measurements of hemoglobin aggregates in single, sickle erythrocytes. Sickle erythrocytes were attached to the poly-(L-lysine)-coated surface of a flow cell. They were exposed to several oxygenation-deoxygenation cycles by repeatedly changing the flowing solution. The rate of cycling was found to be a determining factor for the formation of irreversible morphologic alterations as well as irreversible hemoglobin aggregates. In slow cycling, the sickle erythrocytes took an irreversible, irregular, rounded shape, and hemoglobin aggregates were observed even in the oxygenated state after 20 cycles. In the fast cycling, however, these changes did not take place even after 60 cycles.

The value of the peripheral blood smear in anemic inpatients. The laboratory's reading v a physician's reading.

Since physicians are routinely taught to review the peripheral blood smear results of all anemic patients, we analyzed the diagnostic value of the laboratory's blood smear reading and the incremental value of a physician's personal reading in anemic inpatients. Blood smear abnormalities, as reported by the laboratory and two hematologists, were poorly reproducible, with only five of the 11 types of abnormalities being more reproducible than could be expected by chance. The blood smear performed no better than RBC indices in detecting probable iron deficiency or low serum levels of folate or vitamin B12. In anemias not caused by deficiency states, the blood smear reading performed by the hospital laboratory provided unique information in 6% of the cases and helpful information in another 25%, but the additional reading performed by a hematologist never provided unique information and provided incremental helpful information in only 4% of the cases. The peripheral blood smears of all anemic inpatients should be read by the hospital laboratory, but in our hospital, a routine additional personal reading by a physician had limited incremental value and could be reserved for selected cases.

Blood group antigen deficiencies associated with abnormal red cell shape.

Rare individuals are known with erythrocytes which show an inherited deficiency of certain blood group antigens and also have abnormal red cell shape. Studies of these cells can give an insight into the functional role of blood group active components in maintaining the shape and membrane properties of the normal erythrocyte. The biochemical characterisation of the red cell membrane alterations occurring in two such rare erythrocyte phenotypes--the Leach phenotype and the Rhnull phenotype are reviewed here.

The phospholipid organisation in the membranes of McLeod and Leach phenotype erythrocytes.

The phospholipid composition, the distribution of phospholipids over the two membrane layers as well as the phosphatidylcholine-specific transfer protein-mediated exchangeability of phosphatidylcholine from the membrane, has been investigated in two types of abnormal erythrocytes--the McLeod phenotype and the Leach phenotype. The acanthocytic McLeod cells appeared to have a normal phospholipid composition and distribution, but the exchangeability of phosphatidylcholine was found to be markedly enhanced. Unlike control erythrocytes, in which 75% of all of the phosphatidylcholine can be exchanged during an 8 h incubation, the McLeod cell showed a complete exchange of this phospholipid within the same time period. This obviously indicates an enhanced transbilayer mobility of phosphatidylcholine in the membrane of McLeod cells. Erythrocytes of the Leach phenotype showed an elliptocytic shape and increased osmotic fragility, but no abnormalities were observed as to the composition and organisation of the phospholipid complement of their membranes.

Failure of mean red cell volume to serve as a biologic marker for alcoholism in narcotic dependence. A randomized control trial.

Mean red cell volume, mean red cell hemoglobin, and mean red cell hemoglobin concentration were measured in a prospective, longitudinal, single-bind study of alcoholism and its treatment in 625 patients receiving methadone. Mean red cell volume and mean red cell hemoglobin were significantly elevated in alcoholic as compared with nonalcoholic patients (p less than 0.001), with a sensitivity of 40 and 51 percent, respectively. The ability of an elevated mean red cell volume and mean red cell hemoglobin to exclude active alcoholism (specificity) was 86 and 76 percent, respectively. Development of excessive consumption of alcohol during the course of the study was not associated with significant elevations over baseline values of either mean red cell volume or mean red cell hemoglobin. Similarly, the mean red cell volume and mean red cell hemoglobin in the small number of patients whose consumption of alcohol markedly decreased did not significantly change from baseline values. These findings suggest that although the specificity of mean red cell volume may be helpful in eliminating those persons who are not actively alcoholic, its sensitivity does not permit its use as a biologic marker for alcoholism. The inclusion of an elevated mean red cell volume as a major criterion for the diagnosis of alcoholism should be reconsidered.

Localization of calcium in red blood cells.

The distribution of calcium is demonstrated in human red blood cells (RBC) with a combined phosphate-pyroantimonate technique (PPA). Freshly collected blood and tissue biopsies were initially fixed in potassium phosphate-glutaraldehyde and the complexed calcium was subsequently visualized on Vibratome sections with potassium pyroantimonate. The majority of cells, both in isolated as well as "in situ" preparations, show a fine granular precipitate located at the inner leaflet of the plasma membrane. A minority of cells lack these membrane-associated deposits, exhibiting instead a random distribution of very fine precipitate in their cytoplasm. Capillary endothelial cells and pericytes are devoid of plasma membrane-bound precipitate. When irreversible crenation of RBC is induced by exposure to ionophore A 23187 and calcium, the sphero-echinocytes loose their membrane-bound precipitate, whereas the cells that retain their discocyte shape demonstrate the usual pattern of membrane-bound deposits. Contrarily, cells showing reversible shape changes induced by either A 23187-Ca2+ challenge, by adenosine triphosphate depletion during aging, or contact with lysolecithin, retain or regain the membrane-bound calcium. This cytochemical demonstrable calcium at the inner leaflet of the plasma membrane is probably bound to acidic phospholipids, since it is readily extractable with the nonionic detergent Triton X-100.

Increased cholesterol and decreased fluidity of red cell membranes (spur cell anemia) in progressive intrahepatic cholestasis.

Progressive hemolytic anemia occurred in a 4 1/2-year-old girl with familial intrahepatic cholestasis; a peripheral smear contained bizarre spiculated "spur" red cells. Analysis of this patient's fresh red cells revealed a 59% increase in cholesterol content with a normal phospholipid content and therefore an increase in the cholesterol/phospholipid molar ratio to 1.35 (normal = 0.92). A similar abnormality of lipid composition was present in serum lipoproteins. The lipid abnormality in red cell membrane was associated with a decrease in membrane fluidity, as assessed by the fluorescence polarization of the hydrophobic probe 1,6-diphenyl-1,3,5-hexatriene. Following incubation with patient's plasma, normal cells acquired a spur-shaped morphology with an associated decrease in osmotic fragility and a 25% increase in cholesterol content. The patient's cells, during incubation with normal plasma, acquired morphologic features of spiculated spherocytes with an increase in osmotic fragility and a 21% decrease in cholesterol content. Chenodeoxycholate and lithocholate were present in markedly elevated concentrations in serum. These studies show that a process identical to spur cell anemia in alcoholic cirrhosis may accompany severe liver disease in children with intrahepatic cholestasis.

Reassessment of the microcytic anemia of lead poisoning.

Hematologic abnormalities in childhood lead poisoning may be due, in part, to the presence of other disorders, such as iron deficiency or thalassemia minor. In order to reassess increased lead burden as a cause of microcytic anemia, we studied 58 children with class III or IV lead poisoning, normal iron stores, and no inherited hemoglobinopathy. Anemia occurred in 12% and microcytosis in 21% of these children. The combination of anemia and microcytosis was found in only one of 58 patients (2%). When only children with class IV lead poisoning were studied, the occurrence of microcytosis increased to 46%. However, the combination of microcytosis and anemia was found in only one of these 13 more severely affected patients. Microcytic anemia was similarly uncommon in children with either blood lead concentration greater than or equal to 50 microgram/100 ml. These data indicate that microcytosis and anemia occur much less commonly than previously reported in childhood lead poisoning uncomplicated by other hematologic disorders.

The conjunctival sickling sign, hemoglobin S, and irreversibly sickled erythrocytes.

Sixty-five patients with hemoglobins AS, SC, and SS were investigated in a masked fashion. We observed a statistically significant positive correlation between the severity of conjunctival sickling signs and the counts of irreversibly sickled cells in each hemoglobinopathy group. We also observed a statistically significant positive correlation between the severity of the conjunctival vasculopathy and the percentage of sickle hemoglobin in the total group of patients with hemoglobins AS, SC, and SS.

Changing blood picture in sickle-cell anaemia from shortly after birth to adolescence.

The blood picture of children with sickle-cell anaemia was found to change with age. The changes were most marked in the first year but the mean level of haemoglobin, haemoglobin F, and target cells fell until adolescence, and irreversibly sickled cells rose. Reticulocytes, Howell Jolly bodies, and normablasts altered little after one year. The fall in haemoglobin F suggested a delayed changeover from fetal to adult haemoglobin production. It was concluded that the blood changes in sickle-cell anaemia were progressive throughout childhood.

Duchenne muscular dystrophy: do both parents contribute genetically to the disease?

By observing the effect of 0.08 and 0.02 mg/ml linoleic acid (LA on the electrophoretic mobility of fresh red blood cells derived from the parents of a subject with DMD, it has been shown that all of 16 fathers as well as 15 mothers, consistently differ from normal. In normal subjects, whilst 0.08 mg/ml LA causes increased mobility, 0.02 mg/ml causes reduced mobility (P less than 0.001). In both parents this reversal is abolished and 0.02 mg/ml LA gives the same increased electrophoretic mobility of the RBC as does 0.08 mg/ml. This indicates that there is qualitative alteration of the RBC membrane in both, apparently genetically determined. Only when such an abnormal male mates with an abnormal female can DMD occur in a male offspring; other children appear either normal or showing the same abnormality as do the parents, thus continuing the production of DMD parents, the chance mating of whom produces further DMD. The evidence supports the hypothesis that in DMD there is a widespread membrane disturbance. Other relatives have also been explored. It would appear that the common DMD of children is of autosomal recessive origin with strong limitation to the male.

The distribution of copper in sickling erythrocytes as determined by an IBM cell separator.

Elevated levels of copper have been found in sickling erythrocytes. Since this copper may inhibit sickling or induce hemolysis the authors decided to investigate the distribution of copper in sickling erythrocytes to gain some insight into its origin. When samples of sickling erythrocytes were fractionated by density gradient centrifugation with an IBM cell separator and the fractions analyzed for copper, it was found that the copper to hemoglobin ratio of the different fractions varied several fold. This finding indicated that the copper in sickling erythrocytes did not equilibrate with the copper in serum or other cells and that the copper was present in the cells when they were released into the blood stream. When erythrocytes were obtained from a sickle cell patient four days post-crises, a large amount of residual copper could be observed in the first (youngest) fraction. It was suspected that this copper was in mitochondrial residues. It was also observed that copper levels tended to be higher in control and sicklings erythrocytes during the winter months. The predominance of the first fraction in samples of sickling erythrocytes taken during the winter months suggests that the turnover of sickling erythrocytes is accelerated at this time.

[Behavior of blood composition in chronic liver diseases]. / Comportamento della crasi ematica in epatopazienti cronici.

On the basis of data from hospitalised patients with chronic liver pathology, the relationship between the type and severity of the disease and the nature and extent of changes in blood composition was studied. It is concluded that a direct relationship exists between liver pathology and haemopathy which can be attributed to various aetiopathogenetic factors. The severity of the liver pathology is the main factor, independently of its aetiology.

[Neonatal hemolysis secondary to congenital poikilocytosis]. / Hémolyse néonatale secondaire à une poïkilocytose congénitale.

Hereditary pyropoikilocytosis is a congenital haemolytic anaemia recently described. A new case is reported in which the condition was diagnosed by a study of erythrocyte membrane proteins in the parents. The unusual clinical features of this case lead to a discussion of the relationship between hereditary pyropoikilocytosis and other rare forms of elliptocytosis in children.

[Detection of chronic lead poisoning. Value of the assay of erythrocyte protoporphyrin]. / Dépistage du saturnisme chronique. Intérêt du dosage de la protoporphyrine érythrocytaire.

The most common screening tests for lead poisoning are reviewed. Stippled red cells are inconstant and appear too late. Blood lead concentrations are difficult to measure accurately and often are uncorrelated with body lead stores. Excess of delta aminolevulinic acid and coproporphyrin in urine does not appear early enough. A marked increase of erythrocyte protoporphyrin level practically clinches the diagnosis, later confirmed by increase of lead in urine after an EDTA lead-mobilization test. Measurements of erythrocyte protoporphyrin levels are easy to perform, more sensitive, more precocious and cheaper than the other methods, but their relative lack of specificity must be borne in mind.