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N Sharon

Publications and source records attributed to N Sharon.

At least 91 records · Page 5Linked to original sources
PubMed1989

IL-1 production by T6 (CD1a) positive cord blood mononuclear cells (Langerhan's cell precursors?).

Human cord blood (CB) mononuclear cells were fractionated into peanut agglutinin positive (PNA+) and PNA negative (PNA-) subsets. The PNA+ subset was enriched for T6+(CD1a)Ia+ cells, which we have previously shown to resemble the Langerhans cells (LCs) of the skin, and therefore described as circulating LCs precursors. Supernatants of PNA+ and PNA- cells, and of FACS purified populations of T6+ CB cells, cultured with and without LPS, were tested for IL-1 activity. It was found that cord blood PNA+ mononuclear cells as well as purified populations of T6+ CB cells produce significant amounts of, both extracellular and cell associated, IL-1 as compared to PNA- and T6- cells, and comparable to those produced by macrophages. LPS stimulation mainly affected T6+ cells. It can be concluded that cord blood T6+ cells, presumably LCs precursors, are capable of IL-1 production.

Antigens, CD1↗
PubMed1988

T6 positive cells in the peripheral blood of burn patients: are they Langerhans cells precursors?

Peripheral blood mononuclear cells of 14 patients suffering thermal injury were separated by affinity chromatography on peanut agglutinin (PNA) coupled to Sepharose macrobeads. The resulting PNA positive subset was 14% of the total mononuclear population. About 30% of these cells were found to coexpress T6(CD1), Ia-like and the myeloid differentiation antigens My4(CDw14) and Mo1(CD11). In comparison, the PNA+ subset from normal blood donors (about 5% of total mononuclear cells) contained mature monocytes that were found to be T6 negative. Electron microscopic studies using immunogold labeling showed that the T6 positive cells were slightly smaller than monocytes but larger than the classical lymphocytes and had common morphologic features with the Langerhans cells of the skin. Considering that patients suffering extensive damage of the epidermis require fast renewal of all skin elements, it is possible that the cells we identified in their peripheral blood are the precursors of the Langerhans cells of the skin en route from bone marrow to the epidermis.

Adolescent↗
PubMed1987

Inhibition of yeast binding to mouse peritoneal macrophages by wheat germ agglutinin: a novel effect of the lectin on phagocytic cells.

The ability of wheat germ agglutinin (WGA) to enhance the binding of bacteria and tumor cells to phagocytic cells, and to induce the killing of tumor cells by macrophages and monocytes, is well established. We observed, however, that WGA inhibits the binding to and phagocytosis of yeast cells by thioglycolate-elicited murine peritoneal macrophages. In order to follow these processes rapidly, the yeasts were labeled with Congo-red and their binding to the macrophages was measured spectrophotometrically after treatment with sodium dodecylsulfate. Phagocytosis was also followed by light microscopy. Binding of the yeasts was inhibited by about 80% after pretreating the macrophages with 150 micrograms/ml of WGA. This effect was reversed by subsequent incubation with N-acetyl-D-glucosamine, chitobiose or chitotriose, but was unaffected by methyl alpha-D-mannoside, N-acetyl-D-mannosamine, D-mannose or D-galactose. Pretreatment of the Congo-red yeasts with WGA did not inhibit their binding by the macrophages. Of a variety of lectins tested, only WGA and Datura stramonium lectin had this effect. Pretreating the macrophages with sialidase prevented the inhibition induced by WGA. Our findings suggest the presence on the macrophages of a class of WGA receptors not previously reported.

Animals↗
PubMed1987

The beta 1----2-D-xylose and alpha 1----3-L-fucose substituted N-linked oligosaccharides from Erythrina cristagalli lectin. Isolation, characterisation and comparison with other legume lectins.

The carbohydrate moieties of Erythrina cristagalli lectin were released as oligosaccharides by hydrazinolysis, followed by N-acetylation and reduction with NaB3H4. Fractionation of the tritium-labelled oligosaccharide mixture by Bio-Gel P-4 column chromatography and high-voltage borate electrophoresis revealed that it is composed of five neutral oligosaccharides. Structural studies by sequential exoglycosidase digestion in combination with methylation analysis and two-dimensional 1H-NMR showed that the major component was the fucose-containing heptasaccharide Man alpha 3(Man alpha 6)(Xyl beta 2)Man beta 4GlcNAc beta 4(Fuc alpha 3)GlcNAcol. This is the first report of such a structure in plant lectins. Small amounts of the corresponding afucosyl hexasaccharide were also identified, as well as three other minor components. The structure of the heptasaccharide shows the twin characteristics of a newly established family of N-linked glycans, found to date only in plants. The characteristics are substitution of the common pentasaccharide core [Man alpha 3(Man alpha 6)Man beta 4GlcNAc beta 4GlcNAc] by a D-xylose residue linked beta 1----2 to the beta-mannosyl residue and an L-fucose residue linked alpha 1----3 to the reducing terminal N-acetylglucosamine residue. The oligosaccharide heterogeneity pattern for Erythrina cristagalli lectin was also found for the lectins from four other Erythrina species and the lectins of two other legumes, Sophora japonica and Lonchocarpus capassa.

Carbohydrate Conformation↗
PubMed1987

Bacterial lectins, cell-cell recognition and infectious disease.

Numerous bacterial strains produce surface lectins, commonly in the form of fimbriae that are filamentous assemblies of protein subunits. Among the best characterized of these are the type 1 (mannose specific) fimbrial lectins of Escherichia coli that consist almost exclusively of one class of subunit with a molecular mass of 17 kDa. They possess an extended combining site corresponding to a trisaccharide and preferentially bind carbohydrate units of oligomannose or hybrid type. Type 1 fimbriae also possess a hydrophobic region close to the carbohydrate-binding site, since aromatic alpha-mannosides inhibit strongly (up to 1000-times more than methyl alpha-mannoside) the agglutination of yeasts by the bacteria and the adherence of the latter to pig ileal epithelial cells. The combining sites of type 1 fimbriae of the salmonellae and of other enteric bacteria are different from those of E. coli in that they are smaller and do not possess a hydrophobic region. The various bacterial surface lectins appear to function primarily in the initiation of infection by mediating bacterial adherence to epithelial cells, e.g. in the urinary and gastrointestinal tracts. The mannose specific lectins also act as recognition molecules in lectinophagocytosis (i.e. phagocytosis of the bacteria in the absence of opsonins) by mouse, rat and human peritoneal macrophages, and human polymorphonuclear leukocytes. Affinity chromatography of membrane lysates from human polymorphonuclear leukocytes on immobilized type 1 fimbrial lectin, using methyl alpha-mannoside as eluent, showed that glycoproteins with apparent molecular masses of 70-80, 100 and 150 kDa act as receptors for the bacteria. Inhibition experiments with monoclonal antibodies suggest that the glycoprotein bands of 100 and 150 kDa may be identical with the alpha and beta subunits of leukocyte complement receptors and adhesion glycoproteins involved in complement-mediated opsonophagocytosis. The systems described serve as a fine illustration for the biological role of lectin-carbohydrate interactions. Further studies of these systems will lead to a deeper understanding of the molecular basis of infectious diseases, and perhaps also to new approaches for their prevention.

Animals↗
PubMed1987

Erythrina lectins.

Explore the source record for details and available documents.

Amino Acid Sequence↗
PubMed1987

Aromatic alpha-glycosides of mannose are powerful inhibitors of the adherence of type 1 fimbriated Escherichia coli to yeast and intestinal epithelial cells.

Adherence of bacteria via their surface lectins to host epithelial cells is considered an important initial event in bacterial pathogenesis. Mannose-specific (type 1) fimbriae are among the most commonly found lectins in enterobacteria. We studied the effect of aromatic alpha-glycosides of mannose on the agglutination of mannan-containing yeasts by different strains of Escherichia coli and on the adherence of the bacteria to guinea pig ileal epithelial cells. In both systems these compounds were considerably more effective inhibitors than methyl alpha-mannoside, with 4-methylumbelliferyl alpha-mannoside and p-nitro-o-chlorophenyl alpha-mannoside being the strongest inhibitors. Both compounds were approximately 400-times stronger inhibitors of yeast agglutination by E. coli O128 than was methyl alpha-mannoside and 1,000- and 470-fold stronger, respectively, than was methyl alpha-mannoside in inhibiting the adherence of the bacteria to ileal epithelial cells. 4-Methylumbelliferyl alpha-mannoside was 540 to 1,000 times more effective in inhibiting yeast agglutination by four additional strains of mannose-specific E. coli. It was also more efficient than methyl alpha-mannoside in removing adherent E. coli O128 from ileal epithelial cells. Our results provide further evidence that type 1 fimbriae of E. coli possess a hydrophobic region next to the mannose-binding site. The results suggest that 4-methylumbelliferyl alpha-mannoside and p-nitro-o-chlorophenyl alpha-mannoside are good candidates for the design of therapeutic agents that may prevent adherence in vivo and infection by E. coli strains that express type 1 fimbriae.

Agglutination↗
PubMed1987

Membrane glycoproteins of human polymorphonuclear leukocytes that act as receptors for mannose-specific Escherichia coli.

Type 1 fimbriated (mannose-specific) Escherichia coli cells bind to mannose residues on human polymorphonuclear leukocytes (PMN); this leads to phagocytosis of the bacteria. To identify the mannose-containing receptors on the PMN, the cells were surface labeled with 125I and lysed in 0.5% Nonidet P-40, and the lysate was fractionated by affinity chromatography on a column of Sepharose-bound fimbriae. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of the material eluted from the column with 500 mM methyl-alpha-mannoside revealed two radioactive bands of Mr 70,000 to 80,000 (gp70-80) and 100,000 (gp100). Another weak band of Mr 150,000 (gp150) was observed after prolonged exposure of the gel. Upon blotting of the glycoproteins separated by polyacrylamide gel electrophoresis and overlaying of the blots with concanavalin A, gp150 appeared as the major band. Membrane preparations of the PMN were enriched in gp70-80, gp100, and gp150, in comparison with the cell homogenates, further suggesting that these glycoproteins are surface components. Fractionation of the membrane preparations on the immobilized fimbriae followed by concanavalin A overlay of blots of the methyl-alpha-mannoside-eluted material revealed that gp150 was the major component in this fraction. The eluted fraction, obtained from a cell lysate (4.4 micrograms/ml), inhibited by 70% the agglutination of yeasts by the intact bacteria. Our results suggest that the three surface glycoproteins isolated by us serve as receptors for mannose-specific E. coli on PMN and may be involved in the lectin-mediated phagocytosis of the bacteria.

Bacterial Adhesion↗
PubMed1986

Affinity of four immobilized Erythrina lectins toward various N-linked glycopeptides and related oligosaccharides.

The behavior of N-acetyllactosamine-type oligosaccharides and glycopeptides on columns of four different Erythrina agglutinins immobilized on Sepharose was examined. The sugar-binding specificity of the four lectins is very similar and is directed toward unmasked N-acetyllactosamine sequences, the main difference between the four lectins being the relative strength of interaction of the lectins with a given glycan. Substitution of the N-acetyllactosamine sequences by sialic acid residues, either at O-3 or O-6 of galactose completely abolishes the affinity of the lectins for the saccharides. The presence of one or several alpha-Fuc-(1----3)-GlcNAc groups decreases or completely inhibits the interaction between the glycopeptides and the Erythrina lectins. Substitution of the beta-mannose residue by an additional bisecting beta-(1----4)-N-acetylglucosamine residue decreases the affinity of the lectins for these structures as compared to the unsubstituted ones. Surprisingly, the affinity of the lectins for the oligosaccharides tested is higher than for the corresponding glycopeptides. Our findings show that, after careful calibration with well-defined oligosaccharides and glycopeptides, the immobilized Erythrina agglutinin-Sepharose columns provide valuable tools for the fractionation of N-acetyllactosamine-containing oligosaccharides and glycopeptides.

Carbohydrate Conformation↗
PubMed1986

Identification of glycoproteins that are receptors for peanut agglutinin on immature (cortical) mouse thymocytes.

Binding of peanut agglutinin is being widely used as a marker for immature mouse thymocytes and for the separation of these cells from the mature thymocytes. Two cell surface glycoproteins that bind peanut agglutinin were detected on unfractionated as well as immature thymocytes by lectin overlay and affinity chromatography: one of Mr between 170 000 and 180 000, and the other, a minor component, of Mr 110000, both of which are partially sialylated. No receptors for peanut agglutinin were detected on the mature cells, whereas desialylation experiments revealed the presence of a glycoprotein of Mr 110000. These findings were corroborated by electrophoretic analysis of cell surface glycoproteins of the isolated thymocyte subpopulations labeled in their carbohydrate moieties.

Animals↗
PubMed1986

Identification of peanut agglutinin-binding glycoproteins on immature human thymocytes.

Previous studies in our laboratory have shown that peanut agglutinin (PNA), a lectin specific for the disaccharide Gal beta 3GalNAc, binds to immature (cortical) thymocytes of mouse and man and not to the mature (medullary) cells. Using lectin overlay of protein blots and lectin-affinity chromatography, we have found that the major PNA-binding glycoproteins on total as well as on immature (PNA+) human thymocytes correspond to two bands of Mr 170,000 and 180,000. Another glycoprotein, of Mr 110,000, also binds PNA but to a lesser extent. All three glycoproteins contain sialic acid as demonstrated by cell surface labeling with NaIO4-NaB3H4, binding of wheat germ agglutinin, and reaction with alkaline phosphatase-hydrazide. After treatment with sialidase, binding of PNA to these glycoproteins is significantly enhanced.

Chromatography, Affinity↗
PubMed1986

A subset of human cord blood mononuclear cells is similar to Langerhans cells of the skin: a study with peanut agglutinin and monoclonal antibodies.

Mononuclear cells were fractionated from human cord blood by affinity chromatography on immobilized peanut agglutinin, as previously described (Rosenberg et al., Hum Immunol 7:67, 1983). The PNA+ subset was found to be composed mainly of a population of cells phenotyped as Ia+, T6+, M01+, and MY4+. The presence of mononuclear cells coexpressing these antigens was demonstrated by three techniques: double labeling immunofluorescence using FITC and rhodamine conjugated goat antimouse IgG; fluorescence activated cell sorter (FACS); and by direct counting (under the microscope) of cells stained by either individual or a combination of a variety of monoclonal antibodies. The PNA+ cells expressed cytoplasmic structures similar to Birbeck granules. In view of the fact that Langerhans cells of the skin share a similar phenotype and express Birbeck granules, we suggest that this subset may be the precursor of the Langerhans cells of the skin. In addition, these cells may also be the precursors of the dendritic cells found in the spleen, lymph nodes, thymus, and liver.

Antibodies, Monoclonal↗
PubMed1986

Fractionation of human bone-marrow mononuclear cells with peanut agglutinin: phenotypic characterization with monoclonal antibodies.

Bone marrow mononuclear cells were fractionated by affinity chromatography on immobilized peanut agglutinin (PNA). The resulting PNA+ fraction represented 10% of the total cell number. Twenty percent of the cells within the PNA+ compartment coexpressed the T6, Ia, Mo1, and My4 differentiation antigens and possessed Fc and C3 receptors. The similarity in cell surface antigen phenotype led us to hypothesize that this subset may be a cellular precursor of dendritic cells found in the skin (Langerhans cells) or in the parenchimal organs of the body (D-cells).

Antibodies, Monoclonal↗