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T Feizi

Publications and source records attributed to T Feizi.

At least 127 records · Page 7Linked to original sources
PubMed1987

Neoglycolipid micro-immunoassays applied to the oligosaccharides of human milk galactosyltransferase detect blood-group related antigens on both O- and N-linked chains.

Reduced O-linked chains and reducing N-linked chains were obtained from human milk galactosyltransferase by degradation with alkaline borohydride and hydrazinolysis, and then purified by ion-exchange chromatography. The reactivities of the conjugates of the oligosaccharides with L-alpha-phosphatidyl ethanolamine dipalmitoyl (PPEADP) towards monoclonal anti-Lea and anti-SSEA-1 were then determined, either by antibody-binding assays after absorbing the neoglycolipids onto plastic wells, or by inhibition assays after incorporating the neoglycolipids into liposomes and testing them as inhibitors of antibody binding. The oligosaccharides were also immunostained with monoclonal anti-Lea after h.p.t.l.c. and coupling to PPEADP. Antigenic activities were detected in the O-linked chains by all three assay systems, whereas, for the less abundant N-linked chains, reactivities were detected by the inhibition assays only. The results provide evidence for the expression of Lea and SSEA-1 antigen activities on both the O- and N-linked chains of this enzyme glycoprotein.

Antibodies, Monoclonal↗
PubMed1987

Significance of carbohydrate components of cell surfaces.

This article is focused on a family of carbohydrate structures which are (a) target antigens of autoantibodies and (b) onco-developmental antigens which change during embryonic development, cell differentiation, maturation and oncogenesis. Among the carrier molecules of these saccharide structures is the receptor for epidermal growth factor. Perturbation of these structures on the isolated receptor enhances autophosphorylation of the receptor glycoprotein. This suggests that the carbohydrate chains may be part of a growth regulatory network which may be 'tuned' or perturbed via interactions with endogenous lectins or by adhesins of infective agents. Certain sialylated forms of these oligosaccharide structures serve as receptors for a pathogen of man, Mycoplasma pneumoniae which, following infection, elicits anti-erythrocyte autoantibodies. These autoantibodies are directed against the backbone domain of the carbohydrate receptor and are therefore anti-receptor antibodies. These observations suggest that complex formation between the adhesins of infective agents and specific saccharides of host-cell membranes may be a 'new' mechanism for eliciting autoantibodies.

Antigens, Surface↗
PubMed1986

Sulphate groups are involved in the antigenicity of keratan sulphate and mask i antigen expression on their poly-N-acetyllactosamine backbones. An immunochemical and chromatographic study of keratan sulphate oligosaccharides after desulphation or nitrosation.

Conditions were established for desulphation of hexa-, octa-, deca- and larger oligosaccharides derived from corneal keratan sulphate after treatment with endo-beta-galactosidase. The antigenicities of the desulphated oligosaccharides were compared with those of the native oligosaccharides in chromatogram binding, plastic-plate binding or inhibition of binding assays using a novel microimmunochemical approach with oligosaccharide-lipid conjugates (neoglycolipids). The results clearly show that sulphate residues are essential components of the antigenic determinant(s) recognised by three monoclonal antibodies to keratan sulphate, 5-D-4, 1-B-4 and MZ15, but they mask the i antigen activity of the linear poly-(N-acetyllactosamine) backbones of this glycosaminoglycan. Immunochemical assays, before and after beta-N-acetylglucosaminidase treatment of desulphated linear hexa-, octa- and decasaccharides derived from keratan sulphate, indicate that for reaction with one anti-i antibody, Den, there is an absolute requirement for the non-reducing beta-galactosyl residue of the i antigen structure to be in the terminal position, but with a second anti-i antibody, Tho, there is in addition some reactivity with the i antigen structure having an N-acetylglucosamine residue at the non-reducing end. The chromatographic properties after desulphation or nitrosation of a minor keratan sulphate oligosaccharide (a dodecasaccharide), which reacts especially well with antibody 5-D-4, have provided the first evidence for the presence of glucosamine residues that may be N-sulphated in corneal keratan sulphate.

Animals↗
PubMed1986

Blood-group-related carbohydrate antigens are expressed on human milk galactosyltransferase and are immunogenic in rabbits.

Immunochemical evidence is presented for the presence of blood-group-related carbohydrate structures on human milk galactosyltransferase and for the occurrence of the corresponding specificities among rabbit antibodies to this enzyme. Although these carbohydrate specificities constitute minor populations among antisera and affinity-purified antibodies to galactosyltransferase, their presence is important in the immunohistochemical approach to enzyme localization, since they give rise to strong reactivities with epithelial cells of the gastrointestinal tract.

Animals↗
PubMed1986

Isolation and characterization of sulphated oligosaccharides released from bovine corneal keratan sulphate by the action of endo-beta-galactosidase.

A series of oligosaccharides has been isolated from the keratan sulphate peptidoglycan (3 M NaCl fraction) of bovine cornea after digestion with the endo-beta-galactosidase of Bacteroides fragilis. Structural information on the major oligosaccharides was obtained from (a) their susceptibilities to endo-beta-galactosidase before and after desulphation, (b) their elution positions on a column of Bio-Gel P-4 and retention times on a high-performance anion-exchange column and (c) negative-ion fast-atom-bombardment mass spectrometry. More than 75% of the oligosaccharides were sulphated unbranched poly(N-acetyllactosamine) sequences, (-3/4GlcNAc beta 1-3Gal beta 1-)n, and approximately 3% was the neutral disaccharide, GlcNAc beta 1-3Gal. The sulphated disaccharide, GlcNAc-SO-3 beta 1-3Gal, accounted for almost 35% of the oligosaccharide material while 40% consisted of four oligosaccharides, unbranched tetra-, hexa-, octa- and decasaccharides of poly(N-acetyllactosamine) type, having 3, 5, 7 and 9 sulphate residues respectively. Proton nuclear magnetic resonance studies at 500 MHz (Hounsell, E. F., et al. following paper in this journal) have shown that a sulphate residue is attached to the C-6 position of each N-acetylglucosamine and each internal galactose residue of these four oligosaccharides which express to varying degrees the antigenic determinants recognised by three monoclonal antibodies to keratan sulphate (Mehmet, H. et al., paper which follows the next paper in this journal).

Animals↗
PubMed1986

1H-NMR studies at 500 MHz of a neutral disaccharide and sulphated di-, tetra-, hexa- and larger oligosaccharides obtained by endo-beta-galactosidase treatment of keratan sulphate.

In the preceding paper in this journal, the major oligosaccharides obtained by endo-beta-galactosidase digestion of bovine corneal keratan sulphate were identified as a neutral disaccharide, GlcNAc beta 1-3Gal, and sulphated di-, tetra-, hexa-, octa- and decasaccharides based on the sequence (-3/4GlcNAc beta 1-3Gal beta 1-)n having 1, 3, 5, 7 and 9 sulphate groups, respectively. In the present study, these oligosaccharides have been analysed by 500-MHz 1H-NMR spectroscopy using spin-decoupling and two-dimensional correlated spectroscopy experiments. The NMR data confirm the beta-configuration of all the interglycosidic linkages and are consistent with an alternating sequence of----4GlcNAc and----3Gal, a non-reducing-end N-acetylglucosamine residue and a reducing-end galactose residue. The NMR data have also established that a sulphate group is linked to the C6 position of all sugar residues except the reducing-end galactose as follows: (Formula: see text). The signals of the protons attached to the sulphated carbon atoms show marked downfield shifts (approximately 0.4 ppm from equivalent protons of non-sulphated carbon atoms), while the protons at C5 vicinal to sulphated atoms show a change of 0.1-0.2 ppm and other protons of the sulphated monosaccharides show smaller changes in chemical shift (0.01-0.1 ppm). The proton at C4 of the non-sulphated reducing-end galactose linked at C3 also shows a significant change in chemical shift (0.03 ppm).

Animals↗
PubMed1986

The antigenic determinants recognized by three monoclonal antibodies to keratan sulphate involve sulphated hepta- or larger oligosaccharides of the poly(N-acetyllactosamine) series.

The carbohydrate determinants of keratan sulphate recognized by three monoclonal antibodies (5-D-4, 1-B-4 and MZ15) have been investigated by solid-phase radioimmunoassay using bovine corneal keratan sulphate as the immobilized reference antigen. The antibodies appeared highly specific for sulphated poly(N-acetyllactosamine) sequences, for their binding was strongly inhibited by preparations of keratan sulphate, but not by glycoproteins with non-sulphated poly(N-acetyllactosamine) sequences of I and i antigen types, a desulphated keratan sulphate hexasaccharide, an array of neutral and sulphated mono- and disaccharides and other glycosaminoglycans. Inhibition of binding assays using a series of structurally characterized sulphated di, tetra-, hexa-, octa- and decasaccharides, and partially characterized larger oligosaccharides, isolated from bovine corneal keratan sulphate after digestion with endo-beta-galactosidase (see preceding two papers in this journal) showed that the smallest oligosaccharide reactive with all three antibodies was the linear pentasulphated hexasaccharide, E-II although antibody 1-B-4 reacted with a tetrasulphated analogue. The heptasulphated octasaccharide, G-III, was more active; among the structurally characterized keratan sulphate oligosaccharides the nonasulphated decasaccharide, I-IV, was the most active. Thus, the hepta- and octasaccharide sequences, indicated by brackets below are proposed as candidate antigenic structures recognized by the three monoclonal antibodies. (Formula: see text). Antibody 5-D-4 differs from the other two antibodies in reacting relatively strongly with a minor oligosaccharide which chromatographs as a hexasulphated octasaccharide, G-I, and most strongly with a minor sulphated, linear dodecasaccharide, J-II, which has been partially characterized [Tang, P.W., Scudder, P., Mehmet, H., Hounsell, E. F. & Feizi, T., unpublished results] and may contain N-sulphated glucosamine residues.

Animals↗
PubMed1986

Expression of blood group antigens in urinary tract tumours: prospective fluorescence study using cryostat sections of fresh frozen tissues.

Cryostat sections of fresh frozen tissues were used in a prospective study of blood group H and A antigen fluorescence in 73 transitional cell carcinomas of the bladder. The aim was to evaluate antigen expression without subjecting the tumour tissues to organic solvents that extract blood group active glycolipids. Deletion of the genetically predicted antigen was twice as common in tumours of pT1 or greater stage than those of pTa stage and also twice as common in poorly differentiated than in moderately well differentiated tumours. The considerable heterogeneity and overlap, however, in patterns of reactivity in tumours of various histopathological stages and grades and the effect of secretor status on antigenicity meant that there was no obvious antigenic feature that correlated precisely with invasive stage or differentiation grade. It remains to be determined whether the antigen positive and antigen negative tumours represent different disease entities with differing clinical courses. Our results indicate, however, that studies of the blood group antigens in urinary tract tumours are more likely to be of value in research into biochemical disorders in the neoplastic process than in routine clinical assessment as a guide to treatment.

ABO Blood-Group System↗
PubMed1986

Antibodies to shared idiotypes as agents for analysis and therapy for human B cell tumors.

Monoclonal anti-idiotypic antibodies generated against idiotypic immunoglobulin (Ig) of neoplastic B lymphocytes can be selected from growing hybridoma clones by their ability to recognize idiotypic but not normal IgM. This group of antibodies can be subdivided into those that bind to the target tumor cells in the presence of normal human serum (approximately 85% of the clones) and those in which binding is inhibited by serum (approximately 15%). The former appear to be specific for private idiotypic determinants whereas the latter recognize cross-reacting idiotypic determinants. Such cross-reactivity is reflected both in recognition of a small percentage of normal Ig and also in binding to other lymphomas. The anti-idiotypes specific for private determinants can be used for therapy, with only idiotypic Ig secreted by tumor cells able to block its access to cells. The cross-reacting anti-idiotypes will face in addition the barrier of the proportion of normal Ig with which it reacts. The attraction of using a single monoclonal reagent for more than one patient has led us to develop an assay that measures the level of such blocking and to propose that those recognizing less than 30 micrograms/mL of normal Ig could be placed in a panel for possible therapy for several patients; less restriction need apply to antibodies for monitoring tumor progress. The assay is described, and examples of such antibodies raised against lymphoma cells from two patients are given together with comparisons with them of anti-idiotypes specific for private determinants.

Aged↗
PubMed1985

Novel approach to the study of the antigenicities and receptor functions of carbohydrate chains of glycoproteins.

This report describes the construction of neoglycolipids as a novel approach to determining the antigenicities and receptor functions of minute amounts of oligosaccharides derived from glycoproteins. Reduced oligosaccharides are converted into oligosaccharide alditols by controlled selective periodate oxidation and conjugated to phosphatidyl ethanolamine dipalmitoyl by reductive amination. The resulting neoglycolipids can be rendered multivalent by binding to polyvinylchloride or silica plates or they can be incorporated into liposomes and their antigenicities and receptor activities determined in low concentrations by direct binding or inhibition of binding assays. This approach, which has been successfully used with two monoclonal antibodies and a plant lectin, should be widely applicable to the direct analysis of O- and N-glycosidically linked carbohydrate chains of glycoproteins and proteoglycans both as antigens and recognition structures of diverse receptor systems.

Animals↗
PubMed1985

Differing reactions of monoclonal anti-A antibodies with oligosaccharides related to blood group A.

Inhibition radioimmunoassays with blood group A-related oligosaccharides have been used to investigate the specificities of six monoclonal anti-A antibodies, three of which had been intentionally generated by immunization of mice with blood group A erythrocytes and A-active blood group substance, and three were incidentally produced following immunization of mice with human tonsil cell membranes or a human colon cancer cell line. By hemagglutination, these antibodies are highly specific for human blood group A erythrocytes. However, they differ from one another in their reaction patterns with mono- and difucosyl A antigen structures and the corresponding afucosyl sequences on Type 1 and Type 2 backbone structures. The six antibodies, together with four previously characterized anti-A monoclonal antibodies (originally raised against the receptor for epidermal growth factor) have been classified into five groups. The first two groups consist of antibodies with broad specificities for A-related structures. There are five antibodies in the first group (TL5, 29.1, A17/3D1, MH2/6D4, and MH1/5D1) reacting to varying degrees with the mono- and difucosyl A antigen structures on either type of backbone sequence. In the second group are two antibodies (A15/3D4 and A15/3D3) which are difficult to inhibit with the oligosaccharides tested, but they reacted best with monofucosyl A structure on either type of backbone. Each of the remaining three antibodies had a distinct and more restricted reaction pattern, with a specificity for the difucosyl A antigen on both types of backbone (antibody EGR/G49) or the Type 1-based mono- and difucosyl A antigen structures (antibody MAS 016c) or the Type 2-based monofucosyl A antigen structure (antibody 455). The reactions of four of the antibodies with N-acetylgalactosamine or with oligosaccharides containing the afucosyl sequence GalNAc alpha 1-3Gal suggest that they may react with certain glycoconjugates with alpha-N-acetylgalactosaminyl termini ("A-like" structures) that are unrelated to the products of the blood group A gene-specified alpha-N-acetylgalactosaminyl-transferase. Knowledge of the differing reactions of these monoclonal antibodies is important for interpreting their reactions with glycoproteins and glycolipids of diverse origins.

ABO Blood-Group System↗
PubMed1985

Novel antigenic specificity involving the blood group antigen, Lea, in combination with onco-developmental antigen, SSEA-1, recognized by two monoclonal antibodies to human milk-fat globule membranes.

Two monoclonal antibodies to human milk-fat globule membranes, which recognize an epithelial antigen designated MAM-3c, were found to bind strongly to epithelial glycoproteins derived from non-secretors. Further investigations, using purified glycoproteins and structurally defined oligosaccharides, established that the optimal antigenic structure for both antibodies involves the Type 1 based blood group antigen, Lea, in combination with the Type 2 based onco-developmental antigen, SSEA-1, (Formula: see text) as in lacto-N-difucohexaose II. The antibodies may also react with the corresponding monofucosyl structures lacking the 3- or 4- linked fucose residues and to a lesser extent with the afucosyl tetrasaccharide sequence as in lacto-N-tetraose. The Lea and SSEA-1 antigens are known to occur on human epithelial glycoproteins. However, this is the first report of an antigenic specificity involving a combination of the Type 1 and Type 2 based fuco-oligosaccharides and occurring on epithelial glycoproteins.

Antibodies, Monoclonal↗
PubMed1985

Glycosphingolipid carriers of carbohydrate antigens of human myeloid cells recognized by monoclonal antibodies.

Six monoclonal antibodies with known specificities for the carbohydrate antigens i, X or Y, and seven anti-myeloid antibodies (determinants unknown) selected for their differing reaction patterns with human leucocytes were tested in chromatogram binding assays for reactions with myeloid cell glycolipids derived from normal human granulocytes and chronic myelogenous leukemia cells. Antigenicities were found exclusively on minor glycolipids which were barely or not at all detectable with orcinol-sulphuric acid stain. Among these, a neutral glycosphingolipid bound the anti-i antibody Den and chromatographed as the ceramide octasaccharide, Gal beta 1----4GlcNac beta 1----3Gal beta 1----4GlcNac beta 1----3Gal beta 1----4GlcNAc beta 1----3Gal beta 1----4Glc-Cer. Several species of neutral glycosphingolipids with six to more than ten monosaccharides were detected which carry the X antigen and others the Y antigen: Gal beta 1----4(Fuc alpha 1----3)GlcNAc and Fuc alpha 1----2Gal beta 1----4(Fuc alpha 1----3)GlcNAc, respectively. In addition, three new types of carbohydrate specificities were detected among the myeloid cell glycolipids. Two were associated with neutral glycolipids: the first, recognised by anti-myeloid antibodies VIM-1 and VIM-10, was expressed on a distinct set of glycolipids with six or more monosaccharides, and the second, recognized by VIM-8, was expressed on glycolipids with more than ten monosaccharides. The third specificity, recognised by the anti-myeloid antibody VIM-2, was expressed on slow migrating sialoglycolipids with backbone structures of the poly-N-acetyllactosamine type that are susceptible to degradation with endo-beta-galactosidase. Thus, we conclude that the i and Y antigens occur among the glycolipids of normal myeloid and chronic myelogenous leukemia cells and that a high proportion of hybridoma antibodies raised against differentiation antigens of myeloid cells are directed at carbohydrate structures.

Antibodies, Monoclonal↗
PubMed1985

Multiple proteins related to the soluble galactose-binding animal lectin revealed by a monoclonal anti-lectin antibody.

A monoclonal antibody (NIBy 142-36/8) raised against the soluble galactose-binding lectin of bovine heart muscle has been tested by solid-phase vinyl-plate radiobinding and nitrocellulose immunoblotting with homogenates of various bovine tissues, and the muscle tissues of pig, rabbit, chicken and rat. Muscle lectins of chicken, rabbit and rat differed from those of man and pig in their lack of reactivity with the 36/8 antibody. There was a good correlation of haemagglutinating activities and immunoreactivities of the bovine tissue homogenates, suggesting that the soluble galactose-binding protein is a major haemagglutinin in various tissues. Immunoblotting experiments revealed an array of antigenically active components in the homogenates in addition to the 13 and 26kDa proteins that were previously detected in preparations of purified lectin. These were in the range 36kDa to more than 200kDa, and a different spectrum of immunoreactive components was found in various cell types. Galactose-binding activity was demonstrable in 13, 26 and 36kDa components in certain bovine tissues, suggesting that the immunoreactive components of higher Mr may be inactive precursor forms of the lectin.

Animals↗
PubMed1985

Structural analysis of the O-glycosidically linked core-region oligosaccharides of human meconium glycoproteins which express oncofoetal antigens.

Glycoproteins were extracted from meconium samples of group O neonates of secretor type by pronase digestion followed by precipitation in 67% aqueous ethanol and separated into Ii antigen enriched and depleted fractions by affinity chromatography. The latter fraction strongly expressed the oncofoetal antigens recognised by natural antibodies in mouse sera and the hybridoma antibody FC 10.2, and this activity was enhanced after mild acid hydrolysis to remove sialic acid and fucose residues. Oligosaccharides were released from the mild-acid-treated fraction by base-borohydride degradation and purified by gel permeation chromatography on Bio-Gel P4 and high performance liquid chromatography on octadecylsilyl and aminopropylsilyl columns. The major oligosaccharides were characterised by fast atom bombardment and electron impact mass spectrometry, combined gas-liquid chromatography/mass spectrometry and 500-MHz proton NMR spectroscopy. Their structures, in order of abundance, were: (Formula: see text).

Animals↗
PubMed1985

Transformation and growth related changes in levels of nuclear and cytoplasmic proteins antigenically related to mammalian beta-galactoside-binding lectin.

Immunofluorescence and immunoblotting experiments, using a monoclonal antibody to the 13 kDa mammalian beta-galactoside-binding lectin have shown that human lymphocytes contain nuclear and cytoplasmic proteins of apparent molecular masses of 130, 80, 65 and 13 kDa that are antigenically related to the lectin and whose levels and patterns of expression change in association with transformation, or after stimulation with mitogens. These observations, together with the finding that the myeloid cell line K562 is also rich in the 130 kDa component, whereas the mature granulocytes of normal donors and of patients with chronic myeloid leukaemia are lacking in all of the immunoreactive forms, raise the possibility that this family of lectin-related proteins may be components of growth regulatory systems that are variously elicited in the transformed and stimulated cells.

Antibodies, Monoclonal↗
PubMed1985

The carbohydrate specificities of the monoclonal antibodies 29.1, 455 and 3C1B12 to the epidermal growth factor receptor of A431 cells.

Sixteen hybridoma-derived antibodies to the epidermal growth factor receptor of A431 cells were studied with respect to their reactions with blood group-related carbohydrate structures. Twelve of these were assessed as recognizing carbohydrate determinants on the basis of their immunostaining of reference blood group substances on nitrocellulose paper. Three of these antibodies were further investigated by inhibition of binding assays with glycoproteins and structurally defined oligosaccharides or by haemagglutination of erythrocytes before and after treatment with endo-beta-galactosidase. Two of the antibodies, 29.1 and 455, were shown to have blood group A-related specificities which differed from one another and from those of monoclonal anti-A antibodies described previously. The third antibody, 3C1B12, which was shown to recognize a determinant based on alpha 1----3 fucosylated Type 2 chains on linear and branched backbone sequences, also differs from previously described monoclonal antibodies of 3-fucosyl-N-acetyllactosamine type, such as anti-SSEA-1 (anti-mouse embryo) and several antibodies to human myeloid cells. While these antibodies are invaluable in providing structural information on the carbohydrate chains of the receptor glycoprotein and should help to elucidate their functions, their use as 'anti-receptor' reagents in cell biology will be influenced by the knowledge that the determinants they recognize are shared by other glycoproteins and glycolipids of diverse cell types.

Animals↗