Cooperation of erythrocytes with leukocytes in immune response of a teleost <Emphasis Type="Italic">Oplegnathus fasciatus</Emphasis>

The most abundant cell type in the blood of mammals and fish is erythrocyte. Unlike mammalian erythrocyte, fish erythrocyte is nucleated. The functional differentiation of teleost erythrocyte is insufficient compared with that of mammals. Therefore, fish erythrocyte may have different functions from that of mammals. Functional interaction between erythrocyte and leukocyte was confirmed by the cDNA microarray newly constructed in this study to investigate characterization of rock bream erythrocyte. In this study, different immune related genes of erythrocytes were annotated by microarray analysis. Microarray analysis showed that a total of 338 genes were up-regulated in co-cultured erythrocytes with leukocytes by LPS stimulation when comparing to erythrocytes stimulated LPS. Many genes in erythrocyte of rock bream were up-regulated in presence of leukocytes, suggesting that erythrocytes interact with leukocytes to trigger expression of various genes associated with the immune system. Our results provide valuable information that direct and indirect immunological function of fish erythrocyte.     

Functional analysis of erythrocyte determinants of Plasmodium infection

The Plasmodium falciparum parasite is an obligate intracellular pathogen whose invasion and remodelling of the human erythrocyte results in the clinical manifestations of malarial disease. The functional analysis of erythrocyte determinants of invasion and growth is a relatively unexplored frontier in malaria research, encompassing studies of natural variation of the erythrocyte, as well as genomic, biochemical and chemical biological and transgenic approaches. These studies have allowed the functional analysis of the erythrocyte in vitro, resulting in the discovery of critical erythrocyte determinants of Plasmodium infection. Here, we will focus on the varied approaches used for the study of the erythrocyte in Plasmodium infection, with a particular emphasis on erythrocyte invasion.     

Localization of a parasite encoded protein to erythrocyte cytoplasmic vesicles of Plasmodium falciparum-infected cells

Intracellular development of the malarial parasite results in substantial modifications of the membrane and cytoskeleton of the erythrocyte host cell. Two related Plasmodium falciparum-encoded proteins of 50 kDa and 43 kDa (Pf 50/43), identified by reactivity with a single mAb, were demonstrated to be localized to the erythrocyte cytoplasm of parasite-infected cells. Immunofluorescence and immunoelectron microscopy using mAb.7E11 demonstrated the Pf 50/43 is localized in the membrane of the vesicles in the erythrocyte cytoplasm, vesicles which correspond to Maurer's clefts. Solubility properties of the proteins suggest they are integral membrane proteins. By immunofluorescence, Pf 50/43 is shown to colocalize with actin which has a highly modified organization in the infected erythrocyte. Pf 50/43 is located exclusively in the vesicles, is not transported to the erythrocyte membrane or secreted. It is proposed the vesicles may play a role in transport of molecules across the erythrocyte cytoplasm, between the parasite and the external erythrocyte plasma membrane.     

Mechanisms of cytoskeletal regulation: functional and antigenic diversity in human erythrocyte and brain beta spectrin

A study of human erythrocyte and brain spectrin with particular emphasis on the beta subunits revealed a structural homology but functional dissimilarity between these two molecules. Six monoclonal antibodies raised to human erythrocyte beta spectrin identify three of the four proteolytically defined domains of erythrocyte beta spectrin. Five of these monoclonal antibodies cross-react with human brain spectrin. None of a previously identified set of alpha erythrocyte spectrin monoclonal antibodies [Yurchenco et al: J Biol Chem 257:9102, 1982] reacted with brain spectrin. A domain map generated by limited tryptic digestion shows that brain spectrin is composed of proteolytically resistant domains analogous to erythrocyte spectrin, but the brain protein is more basic. The binding of brain spectrin to erythrocyte ankyrin, both in solution and on erythrocyte IOVs, yielded an association constant approximately 100 time weaker than for erythrocyte spectrin. The binding of azido-calmodulin under native conditions was specific for the erythrocyte beta subunit but was not calcium dependent. In contrast, azido-calmodulin bound only to the alpha subunit of brain spectrin in a calcium-dependent manner. The similarity of structure but modified functional characteristics of the brain and erythrocyte beta spectrins suggest that these proteins serve different cellular roles.     

The formation of vesicles retaining sodium-dependent transport systems for amino acids from protein-depleted membranes of pigeon erythrocytes

The process of the formation of vesicles from pigeon erythrocyte membranes was studied. Mildly alkaline solutions of low ionic strength, which reduce human erythrocyte membranes to small vesicles depleted of spectrin and other proteins, have no such effect on pigeon erythrocyte ghosts. A distinct phase of removal of membrane proteins, including spectrin, began to occur only when pigeon erythrocyte membranes were exposed to 0.2 mM EDTA adjusted to pH values above 10.2. Vesicles which demonstrated Na⁺-dependent amino acid transport were generated between the pH values 10.8 and 11.4. The results show that peripheral proteins, notably spectrin, maintain the integrity of the pigeon erythrocyte ghost. The interaction of these proteins with the membrane is rather different from that well studied in the human erythrocyte ghost and the possible significance of this for the pigeon erythrocyte is discussed.     

亚硒酸钠抗红细胞膜蛋白交联作用的机理探讨

邻苯二酚氧化处理人红细胞膜会导致膜蛋白交联,产生高分子聚合物(HMP)。用N—乙基马来酰胺(NEM)封闭膜蛋白硫基,则不产生HMP。预先用Na SeO_3(0.05mol/L)处理红细胞膜,也同样不产生HMP。用N—(3-芘)马来酰胺(N-〔3-P〕NEM)标记红细胞膜来测试不同浓度Na_2SeO_3对荧光强度的影响。结果表明,随着Na SeO_3浓度增高荧光强度相应降低。Na_2SeO_3对红细胞膜的预处理时间和荧光强度的变化有关。经Na SeO_3处理的红细胞膜ESR谱提示了Na_2SeO_3与材相互作用有关。用荧光法测定膜结合硒含量表明,Na_2SeO_3处理红细胞膜可导致膜结合硒含量增高。推测,Na SeO_3很可能与膜蛋白疏基作用形成结合硒,从而起到抗膜蛋白交联作用。     

Erythrocyte and plasma protein modification in alcoholism: a possible role of acetaldehyde

Analysis of the oxidative modification of plasma and erythrocyte ghost proteins of chronic alcoholic subjects and healthy non-alcoholics has been performed. It was found that increased levels of protein carbonyls in both plasma and erythrocyte ghosts from alcoholic subjects occurred in comparison to the levels found in preparations from non-alcoholics. Plasma proteins from alcoholic subjects did not show evidence of cross-linking, although plasma protein concentration and composition were changed. In alcoholic subjects who displayed no evidence of abnormal erythrocyte morphology no cross-linking of erythrocyte ghost proteins was detectable, whereas the ghosts obtained from alcoholic subjects who displayed morphologically abnormal erythrocytes contained cross-linked proteins. The in vitro treatment with acetaldehyde of erythrocytes from non-alcoholics caused increased levels of protein carbonyls and cross-linking products in erythrocyte ghost preparations which were similar to those found in severe alcoholics. It is concluded that chronic alcohol consumption can cause abnormal erythrocyte morphology and increased erythrocyte fragility as a result of oxidation and cross-linking of erythrocyte ghost proteins. These effects can be ascribed, in part, to exposure of erythrocytes to circulatory acetaldehyde which is a product of ethanol metabolism.     

Relationships between hemorheology, erythrocyte metabolism, and von willebrand factor in athletes and patients with peripheral arterial disease

The relationship between hemorheology, erythrocyte ATP and 2,3-diphosphoglycerate (2,3-DPG) concentrations, and von Willebrand factor antigen was studied in athletes and peripheral arterial disease patients. Lower blood viscosity, mainly due to a higher erythrocyte deformability, was found in athletes compared to control subjects. Higher 2,3-DPG/Ht levels in athletes were correlated with blood viscosity, erythrocyte deformability, the rigidity index, and erythrocyte suspension viscosity at low shear stress. It is suggested that these relationships might be determined by the predominance of immature erythrocytes in the blood circulation of the athletes. In the group of patients, a decrease in ATP/Ht was related to increased erythrocyte aggregation and a higher erythrocyte suspension viscosity. Moreover, the concentration of von Willebrand factor was positively correlated with the erythrocyte aggregation index, erythrocyte suspension viscosity, and plasma viscosity. The results show that alterations in erythrocyte and plasma rheology may be involved in the modification of the functional state of the vascular endothelium and the development of atherosclerosis.     

Effects of aldose reductase inhibitor (ONO-2235) on human erythrocyte sorbitol concentrations in 75 g oral glucose tolerance tests

In order to evaluate the effects of the aldose reductase inhibitor, ONO-2235, on the short-term response of human erythrocyte sorbitol to hyperglycemia in vivo, eleven diet-treated Type 2 (non-insulin-dependent) diabetic patients were studied twice in 75 g oral glucose tolerance tests - with and without ONO-2235 (200 mg p.o.) premedication. The erythrocyte sorbitol concentrations increased with the increments of blood glucose and erythrocyte glucose concentrations in the test performed without ONO-2235. The erythrocyte sorbitol response in the test performed with administration of ONO-2235 30 min prior to glucose load was lower than that in the test performed without ONO-2235 (F = 5.782, P less than 0.05). No significant differences were found between the two tests in blood glucose and erythrocyte glucose concentrations (F = 0.092, P = 0.761; F = 0.029, P = 0.860, respectively). It is concluded that human erythrocyte sorbitol concentrations change promptly in response to rapid changes in erythrocyte glucose concentrations and that administered ONO-2235 is effective in inhibiting the human erythrocyte sorbitol pathway in man.     

The fusion of abnormal plasma lipoprotein (LP-X) and the erythrocyte membrane in patients with cholestasis studied by electronmicroscopy.

Adhesion followed by fusion of LP-X vesicles with the erythrocyte membrane is an important contribution to the erythrocyte enlargement in patients with intra or extra hepatic cholestasis. Adhesion of LP-X vesicles is demonstrated by thin section and freeze-etch electronmicroscopy. Fusion of LP-X with the erythrocyte membrane is deduced from biochemical data and freeze-etch electronmicroscopy in that the uptake of cholesterol and lecithin coincides with the increase in smooth areas on the fracture faces of the erythrocyte membrane.     

Immunospecificity of nuclear antigens in chicken erythroid cells

Summary Specific antisera were produced against chicken reticulocyte dehistonized chromatin. The antisera reacts strongly with chicken reticulocyte chromatin, but only marginally with chicken erythrocyte chromatin. There is no reticulocyte antigen detected in chicken liver. Reticulocyte maturation is accompanied by a gradual decrease in the chromatin immunological activity and template capacity. The reduction of immunological activity is due to the change of chromatin conformation during erythrocyte maturation. Dehistonization and sonication of erythrocyte chromatin raises the erythrocyte chromatin immunological activity to levels similar to those of reticulocyte chromatin. The erythrocyte nuclear antigens are class specific, not being found in frog erythroid cell or murine Friend leukemia cell chromatins.     

The fusion of abnormal plasma lipoprotein (LP-X) and the erythrocyte membrane in patients with cholestasis studied by electronmicroscopy

Adhesion followed by fusion of LP-X vesicles with the erythrocyte membrane is an important contribution to the erythrocyte enlargement in patients with intra or extra hepatic cholestasis. Adhesion of LP-X vesicles is demonstrated by thin section and freeze-etch electronmicroscopy. Fusion of LP-X with the erythrocyte membrane is deduced from biochemical data and freeze-etch electronmicroscopy in that the uptake of cholesterol and lecithin coincides with the increase in smoooth areas on the fracture faces of the erythrocyte membrane.     

Storage-induced changes in erythrocyte membrane proteins promote recognition by autoantibodies

Physiological erythrocyte removal is associated with a selective increase in expression of neoantigens on erythrocytes and their vesicles, and subsequent autologous antibody binding and phagocytosis. Chronic erythrocyte transfusion often leads to immunization and the formation of alloantibodies and autoantibodies. We investigated whether erythrocyte storage leads to the increased expression of non-physiological antigens. Immunoprecipitations were performed with erythrocytes and vesicles from blood bank erythrocyte concentrates of increasing storage periods, using patient plasma containing erythrocyte autoantibodies. Immunoprecipitate composition was identified using proteomics. Patient plasma antibody binding increased with erythrocyte storage time, while the opposite was observed for healthy volunteer plasma, showing that pathology-associated antigenicity changes during erythrocyte storage. Several membrane proteins were identified as candidate antigens. The protein complexes that were precipitated by the patient antibodies in erythrocytes were different from the ones in the vesicles formed during erythrocyte storage, indicating that the storage-associated vesicles have a different immunization potential. Soluble immune mediators including complement factors were present in the patient plasma immunoprecipitates, but not in the allogeneic control immunoprecipitates. The results support the theory that disturbed erythrocyte aging during storage of erythrocyte concentrates contributes to transfusion-induced alloantibody and autoantibody formation.     

The effect of plasma viscosity on the resistance of erythrocyte movement along capillaries

By means of three-dimensional mathematical model describing movement of an asymmetric erythrocyte along the capillary of a small section the effect of the viscosity of the blood plasma on the resistance value to the erythrocyte movement in microvessels was studied. The model takes into account the elastic properties of the erythrocyte, the volume and area of its surface and the mobility of the membrane performing the rotation. It is shown that for characteristic conditions of hemodynamics experimentally observed in the microcirculation system the pressure gradient on the erythrocyte ends is 3-5-fold above the difference of pressures at the ends of plasma column of similar length. The dependence of the pressure gradient at the erythrocyte ends, which accounts for its movement along the capillary, on plasma viscosity is determined at different values of erythrocyte velocity.     

Different reactivities of brain and erythrocyte tubulins toward a sulfhydryl group-directed reagent that inhibits microtubule assembly

There is considerable evidence that tubulin exists in multiple isotypes, differing in amino acid sequence and tissue distribution. Little is known, however, about the functional significance of these isotypes. Chicken erythrocyte beta-tubulin has been shown by peptide mapping to differ significantly from chicken brain beta-tubulin (Murphy, D. B., and Wallis, K. T. (1983) J. Biol. Chem. 258, 7870-7875). We now find that when the two tubulins, in their native states, are incubated with N,N'-ethylenebis(iodoacetamide) (EBI), a bifunctional sulfhydryl-directed reagent, microtubule assembly by brain tubulin is much more sensitive to inhibition by EBI than is erythrocyte tubulin assembly. The resistance of erythrocyte microtubule assembly to inhibition by EBI is correlated with a low reactivity of erythrocyte tubulin with [14C]EBI. This difference is most marked in the beta subunit which reacts 15 and 17% as well, respectively, with [14C]EBI as do the beta 1 and beta 2 subunits of brain tubulin. Also, erythrocyte beta reacts about 33% as well as does brain beta with iodo[14C]acetamide. These results suggest that a reactive sulfhydryl group, whose oxidation prevents microtubule assembly, is present in brain tubulin but absent or inaccessible in erythrocyte tubulin. Since purified erythrocyte tubulin self-aggregates much more readily than does brain tubulin, it is conceivable that erythrocyte and brain tubulin may differ in that the latter may have its assembly subject to a complex regulation, while erythrocyte tubulin assembly may be regulated by a simpler mechanism.     

血红蛋白A_2现象发生机制的研究——“红细胞HbA_2”为HbA_2与HbA的结合产物

为了弄清血红蛋白A_2现象的发生机制,我们对“红细胞HbA_2”的化学组成进行了分析。“红细胞HbA_2”的双向电泳结果表明,它含有两种血红蛋白成分:一种相当于HbA,另一种很可能是溶血液HbA_2。其单向二次电泳结果也证明,它是由溶血液HbA_2和HbA所组成。结果初步说明,盘红细胞中HbA_2可能与HbA结合存在。两者可能有相互作用,也许这是产生血红蛋白A_2现象的原因。     

Viral and non-viral induced fusion of pronase-digested human erythrocyte ghosts.

Human erythrocyte ghosts but was able to fuse only iso-human erythrocyte ghosts. Iso- and hypo-human erythrocyte ghosts were incubated with the proteolytic enzyme pronase under isotonic (iso-human erythrocyte ghosts) or hypotonic (hypo-human erythrocyte ghosts) conditions. Gel electrophoresis and electron microscope (freeze-etching) studies revealed that most of the erythrocyte membrane polypeptides were hydrolyzed by pronase under hypotonic conditions. Sendai virus readily agglutinated both pronase-digested iso-human erythrocyte ghosts and hypo-human erythrocyte ghosts were fused by the non-viral fusogenic agent glyceromonooleate. Freeze-etching studies revealed that during fusion the membranes of pronase-digested human erythrocyte ghosts are intermixed.     

Erythrokinetics In Mice Bearing Tumours In Either Preirradiated Or Unirradiated Tissue

Experiments were designed to clarify the causes of anaemia in hosts bearing tumours in either unirradiated or preirradiated tissue. Isotopic methods are described which enable the estimation of erythrocyte destruction and production rates, and the potential red cell life spans in tumour-bearing animals. In this experimental system, anaemia (a) is in large part due to accelerated random erythrocyte loss, (b) is exacerbated as tumours grow by a progressive reduction in the potential erythrocyte life span due to intrinsic erythrocyte defects, (c) is accompanied by an increase in erythrocyte production of six- to ten-fold and (d) is postponed in onset and decreased in magnitude by preirradiation of the tumour transplant site.     

Tropomyosin from human erythrocyte membrane polymerizes poorly but binds F-actin effectively in the presence and absence of spectrin

Actin in the human erythrocyte forms short protofilaments which are only long enough to accommodate tropomyosin monomers (Shen, B.W., Josephs, R. and Steck, T.L. (1986) J. Cell Biol. 102, 997-1006). This interaction between actin and tropomyosin monomers is predicted to be weak, since tropomyosin polymerization parallels its affinity for F-actin. We examine the binding of human erythrocyte tropomyosin to actin in the presence and absence of spectrin and its ability to polymerize. The binding of human erythrocyte tropomyosin to F-actin is not affected appreciably by the present of spectrin. Saturating F-actin with erythrocyte tropomyosin, however, weakens the binding of spectrin dimers to actin. Although tropomyosin from human erythrocyte and rabbit cardiac muscle have similar affinity for F-actin, the polymerizability of erythrocyte tropomyosin as determined by viscosity measurements is much reduced relative to muscle tropomyosin. This unusual property of erythrocyte tropomyosin is likely due to differences in its primary structure from other known tropomyosin at the amino and carboxyl terminal regions which are responsible for its head-to-tail polymerization and cooperative binding to F-actin. Analysis of the distribution of tyrosine by 2-dimensional tryptic mapping of 125I-labelled erythrocyte tropomyosin shows that tyrosine at positions 162, 214, 221, 261 and 267 in rabbit cardiac tropomyosin are conserved in human erythrocyte tropomyosin but Tyr-60 is absent. This observation suggests that erythrocyte tropomyosin has a carboxyl terminal region similar to its muscle counterparts but its amino terminal region resembles that of platelet tropomyosin which also lacks Tyr-60.