Fractionation of normal and leukemic T-cells by lectin-affinity column chromatography

Omics-based Identification of Glycan Structures as Biomarkers for a Variety of Diseases

Glycans play important roles in cell communication, protein interaction, and immunity, and structural changes in glycans are associated with the regulation of a range of biological pathways involved in disease. However, our understanding of the detailed relationships between specific diseases and glycans is very limited. In this study, we proposed an omics-based method to investigate the correlations between glycans and a wide range of human diseases. We analyzed the gene expression patterns of glycogenes (glycosyltransferases and glycosidases) for 79 different diseases. A biological pathway-based glycogene signature was constructed to identify the alteration in glycan biosynthesis and the associated glycan structures for each disease state. The degradation of N-glycan and keratan sulfate, for example, may promote the growth or metastasis of multiple types of cancer, including endometrial, gastric, and nasopharyngeal. Our results also revealed that commonalities between diseases can be interpreted using glycogene expression patterns, as well as the associated glycan structure patterns at the level of the affected pathway. The proposed method is expected to be useful for understanding the relationships between glycans, glycogenes, and disease and identifying disease-specific glycan biomarkers.

Gallic acid binding to Spatholobus parviflorus lectin provides insight to its quaternary structure forming

Therapeutic effects of gallic acid (GA) have already been extensively studied. However, its interaction with lectins has not gained much attention. It is of interest to validate the binding profile of GA with Spatholobus parviflorus seed lectin. A combination of Isothermal Titration Calorimetry (ITC), haemagglutination assay and molecular docking was applied on SPL-GA interaction. ITC results showed four binding sites, stoichiometry, n=4, irrespective of the ratio of SPL:GA taken for titration. Difference among the four binding sites of a single molecule of SPL with regard to GA binding kinetic parameters was consistently varying. Similarly, the glide scores obtained for GA in the four different binding clefts of SPL were also conformed to the ITC. The binding of GA on SPL without affecting its sugar binding property could be considered as a boon for glycobiological research. From the presented studies, it could be proposed that the SPL-GA interactions may facilitate drug delivery by specific targeting/attachment by profiling of cell-surface glycans, followed by controlled release of drugs.

A novel vasorelaxant lectin purified from seeds of Clathrotropis nitida: partial characterization and immobilization in chitosan beads

A novel lectin from seeds of Clathrotropis nitida (CNA) was purified and characterized. CNA is a glycoprotein containing approximately 3.3% carbohydrates in its structure. CNA promoted intense agglutination of rabbit erythrocytes, which was inhibited by galactosides and porcine stomach mucin (PSM). The lectin maintained its hemagglutinating activity after incubation in a wide range of temperatures (30-60 °C) and pH (6.0-7.0), and its binding activity was dependent on divalent cations (Ca(+2) and Mg(+2)). SDS-PAGE showed an electrophoretic profile consisting of a single band of 28 kDa, as confirmed by electrospray ionization mass spectrometry, which indicated an average molecular mass of 27,406 ± 2 Da and the possible presence of isoforms and glycoforms. In addition, CNA exhibited no toxicity to Artemia sp. nauplii and elicited reversible and dose-dependent vasorelaxation in precontracted aortic rings. CNA was successfully immobilized on chitosan beads and was able to capture PSM in solution. This study demonstrated that CNA is a lectin that has potential as a biotechnological tool in glycomics and glycoproteomics applications.

O-glycosylation of NnTreg lymphocytes recognized by the Amaranthus leucocarpus lectin

O-glycosidically-linked glycans have been involved in development, maturation, homing, and immune regulation in T cells. Previous reports indicate that Amaranthus leucocarpus lectin (ALL), specific for glycans containing galactose-N-acetylgalactosamine and N-acetylgalactosamine, recognizes human naïve CD27⁺CD25⁺CD4⁺ T cells. Our aim was to evaluate the phenotype of CD4⁺ T cells recognized by ALL in peripheral blood mononuclear cells obtained from healthy volunteers. CD4⁺ T cells were isolated by negative selection using magnetic beads-labeled monoclonal antibodies; the expression of T regulatory cell phenotypic markers was assessed on ALL-recognized cells. In addition, IL-4, IL-10, IFN-γ, and TGF-β intracellular production in ALL⁺ cells was also evaluated. The analyses of phenotypic markers and intracellular cytokines were performed through flow cytometry. ALL-recognized CD4⁺ T cells were mainly CD45RA⁺, CCR7⁺ cells. Although 52 ± 10% CD25⁺Foxp3⁺ cells were positive to ALL, only 34 ± 4% of ALL⁺ cells corresponded to CD25⁺Foxp3⁻ cells. Intracellular cytokines in freshly obtained ALL⁺CD4⁺ T cells exhibited 8% of IL-4, 15% of IL-10, 2% of IFN-γ, and 15% of TGF-β, whereas ALL⁻CD4⁺ T cells depicted 1% of IL-4, 2% of IL-10, <1% of IFN-γ, and 6% of TGF-β. Our results show that galactose-N-acetylgalactosamine and N-galactosamine-bearing CD4⁺ T cells expressed phenotypic markers of NnTreg cells.

Separation of hematopoietic stem cells from human peripheral blood through modified polyurethane foaming membranes

Cell separation from peripheral blood was investigated using polyurethane (PU) foam membranes having 5.2 mum pore size and coated with Pluronic F127 or hyaluronic acid. The permeation ratio of hematopoietic stem cells (CD34(+) cells) and lymphocytes through the membranes was lower than for red blood cells and platelets. Adhered cells were detached from membrane surfaces using human serum albumin (HSA) solution after permeation of blood through the membranes, allowing isolation of CD34(+) cells in the permeate (recovery) solution. High-yield isolation of CD34(+) cells was achieved using Pluronic-coated membranes. This was because the Pluronic coating dissolved into the recovery solution at 4 degrees C, releasing adhered cells from the surfaces of the membranes during permeation of HSA solution through these membranes. Dextran and/or bovine serum albumin solutions were also evaluated for use as recovery solutions after blood permeation. A high recovery ratio of CD34(+) cells was achieved at 4 degrees C in a process using 20% dextran solution through PU membranes having carboxylic acid groups.

Purification of 3 monomeric monocot mannose-binding lectins and their evaluation for antipoxviral activity: potential applications in multiple viral diseases caused by enveloped viruses

Three monomeric monocot lectins from Zephyranthes carinata, Zephyranthes candida, and Gloriosa superba with carbohydrate specificity towards mannose derivatives and (or) oligomannose have been isolated and purified from their storage tissues. The lectins were purified by anion-exchange chromatography on DEAE–Sephacyl and by gel filtration chromatography on Biogel P-200 followed by high-performance liquid chromatography. The purified lectins, Z. carinata, Z. candida, and G. superba had molecular masses of 12, 11.5, and 12.5 kDa, respectively, as determined by gel filtration and SDS–PAGE, indicating that they are monomers. In a hapten inhibition assay, methyl-α-d-mannopyranoside inhibited agglutination of both Z. candida and Z. carinata; the latter was also inhibited by Man(α1-2)Man and Man(α1-3)Man. Gloriosa superba showed inhibition only with Man(α1-4)Man of all of the sugars and glycoproteins tested. All purified lectins agglutinated red blood cells from rabbit, whereas G. superba was also reactive towards erythrocytes from guinea pig. All of the lectins were nonglycosylated and did not require metal ions for their activity. They were labile above 60 °C and were affected by denaturing agents such as urea, thiourea, and guanidine–HCl. The lectins were virtually nonmitogenic, like other members of Amaryllidaceae and Liliaceae. Of the 3 lectins, G. superba was found to be highly toxic to the BSC-1 cell line (African green monkey kidney epithelial cells), while both of the Zephyranthes species showed significant in vitro inhibition of poxvirus replication in BSC-1 cells without any toxic effects to the cells. In addition, Z. candida also exhibited significant anticancer activity against SNB-78, a CNS human cancer cell line.

Isolation of a novel N-acetyl-D-lactosamine specific lectin from Alocasia cucullata (Schott.)

An N-acetyl-D: -lactosamine (LacNAc) specific lectin from tubers of Alocasia cucullata was purified by affinity chromatography on asialofetuin-linked amino activated silica. The pure lectin showed a single band in SDS-PAGE at pH 8.8 and was a homotetramer with a subunit molecular mass of 13.5 kDa and native molecular mass of 53 kDa. It was heat stable up to 55 degrees C for 15 min and showed optimum hemagglutination activity from pH 2 to 11. The lectin was affected by denaturing agents such as urea (2 M: ), thiourea (2 M: ) and guanidine-HCl (0.5 M: ) and did not require Ca2+ and Mn2+ for its activity. It was a potent mitogen at 10 microg/ml towards human peripheral blood mononuclear cells with 50% growth inhibitory potential towards SiHa (human cervix ) cancer cell line at 100 microg/ml.

Separation of CD34+ cells from human peripheral blood through polyurethane foaming membranes

Cell separation from peripheral blood was investigated using polyurethane (PU) foaming membranes and PU membranes (pore size, 5 or 12 mum) at different blood permeation speeds. Permeation ratio of hematopoietic stem cells (CD34(+) cells) through the PU membranes was the lowest among the blood cells at any blood permeation speed. This is thought to be because CD34(+) cells are more adhesive than red blood cells (RBCs), platelets, T cells, and B cells. Primitive hematopoietic stem and progenitor cells tend to adhere to the surface of mature blood cells, because of the high expression of cell-adhesion molecules on the surface of the cells. Human serum albumin solution was exposed to PU-COOH membranes to detach adhered cells from the surface of the membranes, allowing isolation of CD34(+) cells and reduction of RBCs in the permeate solution. Most purified CD34(+) cells (high recovery ratio of CD34(+) cells divided by recovery ratio of RBCs) were obtained in the recovery process using PU-COOH membranes (pore size, 5.2 microm) at a permeation speed of 0.3-1 mL/min.

Extraction of leukemia specific glycan motifs in humans by computational glycomics

There have been almost no standard methods for conducting computational analyses on glycan structures in comparison to DNA and proteins. In this paper, we present a novel method for extracting functional motifs from glycan structures using the KEGG/GLYCAN database. First, we developed a new similarity measure for comparing glycan structures taking into account the characteristic mechanisms of glycan biosynthesis, and we tested its ability to classify glycans of different blood components in the framework of support vector machines (SVMs). The results show that our method can successfully classify glycans from four types of human blood components: leukemic cells, erythrocyte, serum, and plasma. Next, we extracted characteristic functional motifs of glycans considered to be specific to each blood component. We predicted the substructure alpha-D-Neup5Ac-(2-->3)-beta-D-Galp-(1-->4)-D-GlcpNAc as a leukemia specific glycan motif. Based on the fact that the Agrocybe cylindracea galectin (ACG) specifically binds to the same substructure, we conducted an experiment using cell agglutination assay and confirmed that this fungal lectin specifically recognized human leukemic cells.

Cell separation between mesenchymal progenitor cells through porous polymeric membranes

This study investigates the separation of two types of marrow stromal cells, KUSA-A1 osteoblasts and H-1/A preadipocytes, by filtration through various porous polymeric membranes. It was found that KUSA-A1 permeates better than H-1/A cells through 12-microm polyurethane foaming membranes. This appears to be due to the relatively smaller cell size of KUSA-A1 cells. In addition, when feed solutions containing suspensions of either cell type or a mixture of the two were used, the permeation ratio was relatively low (< 6%) through polyurethane and surface-modified polyurethane foaming membranes. It was also found that there was some degree of separation between KUSA-A1 and H-1/A cells (separation factor = 1.8) with nylon-net filter membranes, but no separation was obtained when filters made of nonwoven fabrics or silk screens were used. This ability of the nylon-net filter membranes to separate the two cell types was due to a sieving effect that results from an optimal pore size. Finally, permeation of a solution of human serum albumin through the membrane following filtration of the cells did not result in a separation of cells in the recovery solution.

Isolation of an N-acetyl-D-glucosamine specific lectin from the rhizomes of Arundo donax with antiproliferative activity

A lectin with antiproliferative activity towards human cancer cell lines and mitogenic towards human peripheral blood mononuclear cells was purified from the rhizomes of Arundo donax (Linn.) by affinity chromatography on N-acetyl-d-glucosamine linked to epoxy-activated sepharose-6B. The pure preparation apparently yielded a single band of approximately 15 kDa on SDS-PAGE, pH 8.3, under both reducing and non-reducing conditions. The molecular mass of native lectin was 32 kDa as determined by gel filtration chromatography. This showed the lectin to be a dimer, with subunits not held together by disulphide linkages. The A. donax lectin (ADL) agglutinated rabbit erythrocytes and the agglutination was inhibited by N-acetyl-d-glucosamine and its di- and trimer. The lectin was thermostable upto 55 degrees C and showed optimum activity in the range of pH 7.0-9.0 and comprised of 2.1% carbohydrate content.

Relationships between degree of binding, cytotoxicity and cytoagglutinating activity of plant-derived agglutinins in normal lymphocytes and cultured leukemic cell lines

PURPOSE

To clarify the relationships between the degree of lectin-cell binding, cytotoxicity and cytoagglutinating activity of plant-derived lectins in normal lymphocytes and cultured leukemic cell lines.

METHODS

Plant lectins with different quaternary structures and saccharide specificity were used: Dolichos biflorus agglutinin (DBA), Soybean agglutinin (SBA) and Wheat germ agglutinin (WGA). The leukemic cell lines used were: Jurkat, MOLT-4, RPMI-8402, HPB-ALL, CCR-HSB-2 and BALL-1 (derived from acute lymphoblastic leukemia); Raji and Daudi (derived from Burkitt's lymphoma); K-562 (derived from myelogenous leukemia). The lectin-cell binding was detected microscopically and fluorimetrically using FITC-conjugated lectins. Cytotoxicity was estimated by the CellTiter-Glo luminescent cell viability assay, and cytoagglutinating activity by a spectrophotometric method.

RESULTS

The binding of DBA and SBA to normal lymphocytes was negligible, while their binding to leukemic cells increased markedly with increasing lectin concentration. Analogous results were obtained for WGA. However, it was found that WGA also interacted to a significant degree with normal lymphocytes. The degree of lectin-cell binding increased in the order: DBA<SBA<WGA. The cytoagglutinating activity and cytotoxicity of lectins increased in the same order. DBA did not exhibit a cytotoxic effect against normal or leukemic cells, and showed a poor cytoagglutinating activity only in MOLT-4, CCR-HSB-2 and BALL-1 cells. SBA exhibited poor cytotoxicity against Jurkat, RPMI-8402, HPB-ALL and CCR-HSB-2 cells, but a well-defined cytotoxicity against Raji and Daudi cells. SBA showed poor cytoagglutinating activity in leukemic cells. In contrast, WGA at concentrations higher than 0.05 microM showed high cytotoxicity against all leukemic cell lines tested as well as against normal lymphocytes. WGA also showed a well-expressed cytoagglutinating effect in all cell lines except normal lymphocytes. There was a moderate inverse correlation between cell viability and the velocity of cytoagglutination ( r=-0.56, P<0.001), and a good correlation between cell viability and the degree of lectin-cell binding ( r=-0.75, P<0.001). There was a low positive correlation between the velocity of cytoagglutination and the degree of lectin-cell binding ( r=0.43, P<0.001).

CONCLUSION

The results suggest that the lectins that bound most strongly to leukemic cells expressed higher cytotoxic and cytoagglutinating activities.

Interaction of soybean agglutinin with leukemic T-cells and its use for their in vitro separation from normal lymphocytes by lectin-affinity chromatography

A procedure for separation of leukemic T-cells from normal lymphocytes, using lectin-affinity column chromatography, is described. CNBr-activated Sepharose 6MB was used as a non-mobile phase. The gel was covalently coupled with soybean agglutinin (SBA), then served as an affinity probe for fractionation of mixture of normal lymphocytes and leukemic cells. Leukemic cell lines, derived from acute lymphoblastic leukemia (Jurkat, MOLT-4, RPMI-8402), were tested. The elution of normal lymphocytes was carried out by PBS(-). The leukemic T-cells, interacting with SBA, were removed by N-acetyl-D-galactosamine or low-concentration acetic acid. The type and viability of the separated cell fractions were analyzed by flow cytometry and fluorescent microscopy, using adequate fluorescent antibodies. The interaction of leukemic T-cells with free SBA, as well as with SBA-conjugated Sepharose beads, was examined fluorimetrically and visualized by fluorescent microscopy, using FITC-SBA as a marker. The rate of cell elution on SBA-affinity column decreased in order: normal > leukemic T-cells. Both normal lymphocytes and leukemic T-cells were removed in a mixture from SBA-free Sepharose 6MB by PBS(-) and were not fractionated discretely. The leukemic T-cells specifically interacted with SBA as well as with SBA-affinity adsorbent. In contrast, the normal lymphocytes did not interact with free SBA as well as with SBA-conjugated Sepharose beads in the concentrations applied. The method potentially combines a discrete cell fractionation with manifestation of a specific target cytotoxicity of SBA against leukemic T-cells, without any influence on normal lymphocytes.

Purification of normal lymphocytes from leukemic T-cells by lectin-affinity adsorbents - correlation with lectin-cell binding

Utilization of leukemic T-cells from normal ones, using lectin-affinity adsorbents, is described. CNBr-activated Sepharose 6MB was covalently coupled to Soybean (SBA) or Dolichos Biflorus Agglutinins (DBA), then serves as an affinity probe for separation of leukemic T-cells from normal lymphocytes. The normal lymphocytes were removed almost completely by phosphate buffered saline (Ca(2+) and Mg(2+) free) (PBS(-)) from lectin-affinity column. More than 80% of the leukemic T-cells were retained on the lectin-affinity adsorbent, whereas another 10-15% were easily removed by PBS(-). There was a very good linear correlation between percent of cells, retained on the lectin-affinity adsorbent and percent of cells, interacting with the respective free lectin (r=0.97 for SBA, and r=0.93 for DBA). The viability of normal lymphocytes was not influenced after passing through the columns. In the case of leukemic T-cells - about 90% of the easily removed cells were dead, and another 10% were viable cells, non-interacting with DBA or SBA.