Regional differences in the distribution of endogenous receptors for carbohydrate constituents of cellular glycoconjugates,especially lectins,in cortex,hippocampus, basal ganglia and thalamus of adult human brain

Summary Ten different types of labelled neoglycoproteins, exposing glycohistochemically pivotal carbohydrate moieties that mostly are constituents of naturally occurring glycoconjugates with an aromatic spacer, were synthesized. The panel was applied to fixed, paraffin-embedded sections of different cortical regions and white matter, of hippocampal gyrus, basal ganglia, thalamus nuclei and adjacent areas of adult human brain to comprehensively map the presence of respective binding sites in these parts. Compliance with accepted criteria for specificity of binding was routinely ascertained. Overall, not a uniform binding pattern, but a distinct distribution with regional differences on the level of specific cytoplasmic and nuclear staining in nerve cells was determined, fiber structures being generally labelled with medium or strong intensity. For example, among the neurons localized in the five cortical laminae the binding of N-acetyl-d-galactosamine varied from strong to undetectable. Biochemical analysis, employing carbohydrate residues as affinity ligands in chromatography, proved that the neuroanatomically different regions exhibited a pattern of receptors with notable similarities. These results on endogenous binding sites for glycoconjugates, especially lectins, are complementary to assessment of localization of cellular glycoconjugates by plant lectins and carbohydrate-specific monoclonal antibodies. They are thus a further obligatory step to substantiate the physiological roles of recognitive protein-carbohydrate interactions in the central nervous system.     

Detection and mapping of endogenous receptors for carrier-immobilized constituents of glycoconjugates (lectins) by labelled (neo)glycoproteins and by affinity chromatography in human adult mesencephalon, pons, medulla oblongata and cerebellum

Different carrier-immobilized carbohydrate moieties were employed as tools to detect respective binding sites glycohistochemically and glycobiochemically. Besides ascertaining their presence the pattern of endogenous sugar receptors (lectins) in different regions of the human central nervous system was mapped to reveal any non-uniform expression. A strong and specific staining with biotinylated neoglycoproteins, exposing different sugar moieties as ligands, indicated the presence of sugar receptors in the nuclei, neuronal pathways and accessory structures such as ependyma cells, plexus chorioideus, intra- and extracerebral vessels and leptomeninges localized in the mesencephalon, in the pons, in the medulla oblongata and in the cerebellum. Significant differences were seen for various neuroanatomical regions like nerve cells in the basal and central regions of the nuclei pontis in the glycohistochemically detected level of expression of endogenous sugar receptors (lectins). The used approach with carbohydrate constituents of cellular glycoconjugates as ligands in search of specific receptors complemented studies on the localization of glycoconjugates with sugar-specific tools like plant lectins. Exemplary glycobiochemical investigations on the medulla oblongata and cerebellum were performed to investigate the molecular nature of sugar receptors detected glycohistochemically. Despite notable overall similarities, carbohydrate-binding proteins of differing molecular weight can be isolated from these two regions of the central nervous system, namely in the case of receptors with specificity to beta-galactoside termini, to N-acetyl-D-galactosamine and N-acetyl-D-glucosamine and to D-xylose. These combined glycohistochemical and glycobiochemical results serve as a guideline for exploring the physiological relevance of the detected regional differences.     

Lectin binding to the egg envelopes in Eyprepocnemis plorans (Charp.) (Orthoptera, Acrididae)

The distribution of glycoconjugates in the egg envelopes of Eyprepocnemis plorans was investigated using various FITC-conjugated lectins. In the epichorion, the lectins ConA, SBA and WGA each have particular binding patterns, while TPA binding is confined to its deepest regions only. The glycoconjugates of the micropylar wall present different characteristics from those of the surrounding chorion. The vitelline coat shows a marked binding for WGA and TPA only; below the inner micropylar openings, this binding pattern is uniform over the whole extent of the coat and therefore it is not possible to identify specific binding sites for these two lectins. Contrary to what has been observed in some other insect species, the vitelline coat does not seem to be involved in the structural organization of the mycropyles.     

Expression pattern of glycoconjugates in rat retina as analysed by lectin histochemistry

The present study sought to characterize the expression and distribution of complex glycoconjugates in the rat retina by lectin histochemistry, using a panel of 21 different lectins with different carbohydrate specificities. Paraffin sections of Carnoy-fixed Sprague-Dawley rat eyes were stained with various biotinylated lectins, followed by the streptavidin-peroxidase and glucose oxidase-diaminobenzidine-nickel staining procedures. The results showed that the retinal pigment epithelium was stained intensely with LCA, Jacalin, WFA, S-WGA, PWA, DSA, UEA-I, LTA and PHA-E, suggesting that this epithelium contained glycoconjugates with alpha-Man, alpha-Glc, alpha-Gal/GalNAc, beta-GalNAc, alpha-Fuc, NeuAc and other oligosaccharide residues. The outer and inner segments of the photoreceptor layer showed different lectin binding affinities. The outer segments reacted with S-WGA and GS-II, whereas the inner segments reacted with UEA-II, UEA-I, LTA and MAA, suggesting that the inner segments contained glycoconjugates rich in alpha-Fuc and NeuAc(alpha2,3)Gal residues. PNA labelled specifically the cones and could be used as a specific marker for these photoreceptors. RCA-I, WFA, S-WGA, DSA, MAA and PHA-E reacted with both the outer and inner plexiform layers. On the other hand, UEA-I and LTA specifically labelled the outer plexiform layer, while PNA labelled the inner plexiform layer. The retinal microglial cells were labelled specifically by GS-I-B4 and SNA. Interestingly, we also observed that WFA bound specifically to Müller cells and could be used as a novel marker for this retinal glial cell. The capillaries and larger vessels in the retina and choriocapillaris reacted intensely with GS-I-B4, RCA-I, S-WGA, PWA, DSA and PHA-E. No significant differences in lectin binding were observed in the microvessels at these two sites. In summary, the present study demonstrated the expression patterns of glycoconjugates in the rat retina and that certain lectins could be used as histochemical markers for specific structural and cellular components of the rat retina.     

Detection and mapping of endogenous receptors for carrier-immobilized constituents of glycoconjugates (lectins) by labelled (neo)glycoproteins and by affinity chromatography in human adult mesencephalon,pons, medulla oblongata and cerebellum

Summary Different carrier-immobilized carbohydrate moieties were employed as tools to detect respective binding sites glycohistochemically and glycobiochemically. Besides ascertaining their presence the pattern of endogenous sugar receptors (lectins) in different regions of the human central nervous system was mapped to reveal any non-uniform expression. A strong and specific staining with biotinylated neoglycoproteins, exposing different sugar moieties as ligands, indicated the presence of sugar receptors in the nuclei, neuronal pathways and accessory structures such as ependyma cells, plexus chorioideus, intra- and extracerebral vessels and leptomeninges localized in the mesencephalon, in the pons, in the medulla oblongata and in the cerebellum. Significant differences were seen for various neuroanatomical regions like nerve cells in the basal and central regions of the nuclei pontis in the glycohistochemically detected level of expression of endogenous sugar receptors (lectins). The used approach with carbohydrate constituents of cellular glycoconjugates as ligands in search of specific receptors complemented studies on the localization of glycoconjugates with sugar-specific tools like plant lectins. Exemplary glycobiochemical investigations on the medulla oblongata and cerebellum were performed to investigate the molecular nature of sugar receptors detected glycohistochemically. Despite notable overall similarities, carbohydrate-binding proteins of differing molecular weight can be isolated from these two regions of the central nervous system, namely in the case of receptors with specificity to -galactoside termini, to N-acetyl-d-galactosamine and N-acetyl-d-glucosamine and to d-xylose. These combined glycohistochemical and glycobiochemical results serve as a guideline for exploring the physiological relevance of the detected regional differences.     

Expression pattern of Glycoconjugates in Rat Retina as Analysed by Lectin Histochemistry

The present study sought to characterize the expression and distribution of complex glycoconjugates in the rat retina by lectin histochemistry, using a panel of 21 different lectins with different carbohydrate specificities. Paraffin sections of Carnoy-fixed Sprague–Dawley rat eyes were stained with various biotinylated lectins, followed by the streptavidin-peroxidase and glucose oxidase–diaminobenzidine–nickel staining procedures. The results showed that the retinal pigment epithelium was stained intensely with LCA, Jacalin, WFA, S-WGA, PWA, DSA, UEA-I, LTA and PHA-E, suggesting that this epithelium contained glycoconjugates with α-Man, α-Glc, α-Gal/GalNAc, β-GalNAc, α-Fuc, NeuAc and other oligosaccharide residues. The outer and inner segments of the photoreceptor layer showed different lectin binding affinities. The outer segments reacted with S-WGA and GS-II, whereas the inner segments reacted with UEA-II, UEA-I, LTA and MAA, suggesting that the inner segments contained glycoconjugates rich in α-Fuc and NeuAc(α2,3)Gal residues. PNA labelled specifically the cones and could be used as a specific marker for these photoreceptors. RCA-I, WFA, S-WGA, DSA, MAA and PHA-E reacted with both the outer and inner plexiform layers. On the other hand, UEA-I and LTA specifically labelled the outer plexiform layer, while PNA labelled the inner plexiform layer. The retinal microglial cells were labelled specifically by GS-I-B₄ and SNA. Interestingly, we also observed that WFA bound specifically to Müller cells and could be used as a novel marker for this retinal glial cell. The capillaries and larger vessels in the retina and choriocapillaris reacted intensely with GS-I-B₄, RCA-I, S-WGA, PWA, DSA and PHA-E. No significant differences in lectin binding were observed in the microvessels at these two sites. In summary, the present study demonstrated the expression patterns of glycoconjugates in the rat retina and that certain lectins could be used as histochemical markers for specific structural and cellular components of the rat retina.     

Lectin histochemistry of the hyaline layer in the asteroid,pisaster ochraceus

Six different lectins were used to study the carbohydrate nature of the hyaline layer (HL), the external extracellular matrix of the starfish embryo. Thin sections of embryos fixed in the late gastrula stage were incubated with five fluoresceinated lectins: Con A, WGA, RCA, UEA-I, and SBA. All but UEA-I labelled the HL, suggesting that the following sugars are present: mannose and/or glucose, glcNAc and/or Neu5Ac, galactose, and galNAc. The different lectins produced variable degrees of labelling, with WGA, RCA, and SBA producing more intense labelling than Con A. Binding of lectins by the HL was studied at the ultrastructural level by exposing ultrathin sections to the following lectin-gold conjugates: Con A, WGA, PNA, SBA, and LFA. Lectin binding was observed over the various regions of the HL, recognized by Crawford and Abed (J. Morphol. 176:235–246, '86), i.e., the intervillus layer, the supporting layer and the coarse outer meshwork. Local differences in labelling patterns were observed among the various lectins, with SBA labelling all regions intensely, WGA and PNA labelling the supporting layer predominantly, and Con A labelling the HL only lightly. No labelling was observed with LFA. These lectin-labelling patterns in the HL demonstrate the presence of different glycoconjugates in different regions of the HL, suggesting that the layers differ biochemically. The existence of biochemical differences strengthens the idea that each layer may have different functions in the developing starfish embryo.     

Lectin histochemistry of rainbow trout (Oncorhynchus mykiss) gill and skin

In order to characterize the glycoconjugate residues in skin and gills of the adult rainbow trout, the binding pattern of five biotinylated lectins with different carbohydrate specificities was examined. In the skin, mucous cells revealed binding sites for PNA and SBA; filament-containing cells were additionally labelled with Con A. However, the basal cell layer showed no reaction. In the gill, subpopulations of mucous cells reacted with Con A, PNA, SBA and UEA-I. This broader spectrum of glycoconjugates in gill mucous cells compared with the epidermal mucous cells could point to the additional function of gill mucus in ion and osmoregulation. Lectin binding sites were less common in the respiratory epithelial cells of the secondary lamellae than in those of the primary lamellae. Chloride cells revealed mannose, galactose and fucose residues. Immature chloride cells, as indicated by a comparison with Na⁺/K⁺ ATPase immunolabelling, reacted with Con A; subpopulations of them reacted with PNA, SBA and UEA-I. The results form the basis for further investigations in which these cell populations can be analysed under different environmental conditions     

Glycoconjugate pattern of membranes in the acinar cell of the rat pancreas

Lectin-binding studies were performed at the ultrastructural level to characterize glycoconjugate patterns on membrane systems in pancreatic acinar cells of the rat. Five lectins reacting with different sugar moieties were applied to ultrathin frozen sections: concanavalin A (ConA): glucose, mannose; wheat-germ agglutinin (WGA): N-acetylglucosamine, sialic acid; Ricinus communis agglutinin I (RCA I): galactose; Ulex europaeus agglutinin I (UEA I): L-fucose; soybean agglutinin (SBA): N-acetylgalactosamine). Binding sites of lectins were visualized either by direct conjugation to colloidal gold or by the use of a three-step procedure involving additional immune reactions. The rough endoplasmic reticulum and the nuclear envelope of acinar cells was selectively labelled for ConA. The membranes of the Golgi apparatus bound all lectins applied with an increasing intensity proceeding from the cis- to the trans-Golgi area for SBA, UEA I and WGA. In contrast RCA I selectively labelled the trans-Golgi cisternae. The membranes of condensing vacuoles and zymogen granules were labelled for all lectins used although the density of the label differed between the lectins. In contrast the content of zymogen granules failed to bind SBA and WGA. Lysosomal bodies (membranes and content) revealed binding sites for all lectins used. The plasma membranes were heavily labelled by all lectins except for SBA which showed only a weak binding to the lateral and the apical plasma membrane. These results are in accordance to current biochemical knowledge of the successive steps in the glycosylation of membrane proteins. It could be demonstrated, that the cryo-section technique is suitable for the fine structural localisation of surface glycoconjugates of plasma membranes and internal membranes in pancreatic acinar cells using plant lectins.     

Lectin histochemistry of rainbow trout (Oncorhynchus mykiss) gill and skin

In order to characterize the glycoconjugate residues in skin and gills of the adult rainbow trout, the binding pattern of five biotinylated lectins with different carbohydrate specificities was examined. In the skin, mucous cells revealed binding sites for PNA and SBA; filament-containing cells were additionally labelled with Con A. However, the basal cell layer showed no reaction. In the gill, subpopulations of mucous cells reacted with Con A, PNA, SBA and UEA-I. This broader spectrum of glycoconjugates in gill mucous cells compared with the epidermal mucous cells could point to the additional function of gill mucus in ion and osmoregulation. Lectin binding sites were less common in the respiratory epithelial cells of the secondary lamellae than in those of the primary lamellae. Chloride cells revealed mannose, galactose and fucose residues. Immature chloride cells, as indicated by a comparison with Na⁺/K⁺ ATPase immunolabelling, reacted with Con A; subpopulations of them reacted with PNA, SBA and UEA-I. The results form the basis for further investigations in which these cell populations can be analysed under different environmental conditions This revised version was published online in November 2006 with corrections to the Cover Date.     

Distribution of glycoconjugates on the plasma membrane and on membranes of the open-canalicular system in human platelets. A cytochemical study

Distribution of carbohydrate moieties in the membrane system of the human blood platelet was studied by electron microscopy employing lectins as a probe. Glutaraldehyde-fixed platelets were treated with biotinylated-lectins (ConA, RCA, WGA, PNA, SBA, DBA and UEA-1) and labeled with horseradish peroxidase-conjugated avidin. Among the lectins used, ConA bound uniformly to the plasma membrane as well as to the membrane of the open-canalicular system (OCS). Other lectins showed more or less reduced binding on the OCS membrane compared with that on the plasma membrane, indicating that there exist regional differences in the distribution pattern of glycoconjugates in the membrane system of the platelet. The relationship of the distribution pattern of the glycoconjugates with the distribution of the major platelet glycoproteins GPIb and GPIIbIIIa is discussed.     

A comparative study of bark lectins from three elderberry (Sambucus) species

Three elderberry lectins isolated from the bark of three different species of the genus Sambucus which are native to Europe (S. nigra), North America (S. canadensis), and Japan (S. sieboldiana) were studied comparatively with regard to their carbohydrate binding properties and some structural features. All three lectins contained two identical carbohydrate binding sites per molecule and showed a very high specificity for the Neu5Ac(alpha 2-6)-Gal/GalNAc sequence. However, relative affinities for various oligosaccharides were significantly different among them, suggesting differences in the detailed structure of the carbohydrate binding sites of these lectins. The three lectins were immunologically related, but not identical, and all were composed of hydrophobic and hydrophilic subunit regions, although the molecular sizes of these subunits were slightly different among the three lectins. N-terminal sequence analysis of the subunits of these lectins suggested that they have a very similar structure in this region but also indicated the occurrence of N-terminal processing such as the deletion of several amino acid residues at the N-termini for both hydrophobic and hydrophilic subunits of all three lectins. Tryptic peptide mapping of the three lectins showed a similar pattern for all of them but also showed the presence of some unique peptides for each lectin.     

Light microscopic detection of sugar residues in glycoconjugates of salivary glands and the pancreas with lectin-horseradish peroxidase conjugates. II. Rat

Summary Salivary glands and pancreases from male rats were stained with a battery of ten different lectin-horseradish peroxidase conjugates. Qualitative and quantitative differences were observed in the content of terminal sugar residues in stored secretory glycoproteins in parenchymal cells of glands having a similar histological structure. Heterogeneity in the content of secretory glycoconjugates was also found between cells in the same exocrine glands, which were previously thought to be identical on the basis of classical morphological and histochemical staining studies. Similar differences were observed in the structure of glycoconjugates associated with the apical surface of epithelial cells lining glandular excretory ducts. Intercalated ducts presented a gland specific staining pattern different from that of the glandular secretory cell population, whereas striated duct and interlobular duct epithelial cells stained similarly in all major rat exocrine glands. A comparison of lectin binding patterns in identical histological sites in the mouse, reported in a companion paper, is provided, and the similarities and differences between these two rodent species are discussed. In addition to providing valuable information concerning the localization and structure of tissue complex carbohydrates, a comparison of staining in the same tissue sites with labelled lectins reported biochemically to have similar binding specificity has revealed interesting differences in the binding specificity of these macromolecules.     

Treatment with digestive agents reveals several glycoconjugates specifically associated with rat neuromuscular junction.

The lectins DBA, WGA, SBA, Con A, GS-1, LFA and PNA were used to characterize the carbohydrate domains of the rat neuromuscular junction. DBA stained only the synaptic domains of muscle surface. All other lectins stained the whole muscle surface but the intensity of staining was stronger at the synaptic regions. However, when sections were treated with several digestive agents prior to lectin application, the lectin staining pattern changed dramatically. Collagenase-sensitive GlcNac, Mannose, Sialic acid, and GalNac-containing glycoconjugates associated with synaptic regions but not present extrasynaptically were revealed after chemical treatment. On the basis of these modifications it is proposed that, apart from the synapse-specific GalNac-containing glycoconjugate already described elsewhere, new carbohydrate-containing compounds are evidenced. These results provide a new insight into regional specialization of the extracellular matrix associated with the neuromuscular junctions and indicates that pretreatment with various agents, not necessary digestive substances, may alter molecular properties of muscle membrane and uncover previously unknown binding sites.     

Lectin binding pattern and proteoglycan distribution in human eccrine sweat glands

The distribution pattern of glycoconjugates in human eccrine sweat glands has been studied by the binding of newly discovered lectins and by antibodies against a chondroitin sulphate proteoglycan and chondroitin sulphate glycosaminoglycans. Mannose-specific lectins labelled large intracellular granules, part of which could be extended cisternae of the endoplasmic reticulum or Golgi apparatus. In contrast, lectins specific for terminal mannose/glucose residues predominantly labelled basement membranes and the glycocalyx. Lectins recognizing terminal N-acetylgalactosamine groups left most parts of the glands unstained, but stained some dark cells intensely. These last cells were also intensively labelled by N-acetylglucosamine-specific and by fucose-specific lectins. Sialic acid residues were preferentially located in luminal borders of secretory coils. No terminal galactose residues were detected. All antibodies against chondroitin glycoconjugates stained large granules similar to those revealed by the mannose-specific lectins in the secretory cells. The basement membrane is only stained by the proteoglycan antibody and the chondroitin-6-sulphate antibody.Thus, a complex composition of glycoconjugates exists not only in matrix elements but also in the cells of eccrine glands of the human skin. A possible secretion of glycoconjugates is discussed.     

Lectin histochemistry of the gastric mucosa in normal and Helicobacter pylori infected guinea-pigs

Helicobacter pylori attaches via lectins, carbohydrate binding proteins, to the carbohydrate residues of gastric mucins. Guinea-pigs are a suitable model for a H. pylori infection and thus the carbohydrate composition of normal and H. pylori infected gastric mucosa was investigated by lectin histochemistry. The stomach of all infected animals showed signs of an active chronic gastritis in their mucosa, whereas no inflammation was present in the control animals. The corpus–fundus regions of the controls showed heterogeneous WGA, SNA-I, UEA-I and HPA binding in almost all parts of the gastric glands. While these lectins labelled the superficial mucous cells and chief cells heterogeneously, the staining of the parietal cells was limited to WGA and PHA-L. Mucous neck cells reacted heterogeneously with UEA-I, HPA, WGA and PHA-L. In the antrum, the superficial mucous cells and glands were stained by WGA, UEA-I, HPA, SNA-I or PHA-L. WGA, UEA-I, SNA-I and HPA labelled the surface lining cells strongly. The mucoid glands reacted heterogeneously with WGA, UEA-I, HPA, SNA-I and PHA-L. In both regions, the H. pylori infected animals showed similar lectin binding pattern as the controls. No significant differences in the lectin binding pattern and thus in the carbohydrate composition between normal and H. pylori infected mucosa could be detected, hence H. pylori does not induce any changes in the glycosylation of the mucosa of the guinea-pig. This unaltered glycosylation is of particular relevance for the sialic acid binding lectin SNA-I as H. pylori uses sialic acid binding adhesin for its attachment to the mucosa. As sialic acid binding sites are already expressed in the normal mucosa H. pylori can immediately attach via its sialic acid binding adhesin to the mucosa making the guinea-pig particularly useful as a model organism.This work is dedicated to Professor B. Tillmann on the occasion of his 65th birthday     

Treatment with digestive agents reveals several glycoconjugates specifically associated with rat neuromuscular junction

Summary The lectins DBA, WGA, SBA, Con A, GS-1, LFA and PNA were used to characterize the carbohydrate domains of the rat neuromuscular junction. DBA stained only the synaptic domains of muscle surface. All other lectins stained the whole muscle surface but the intensity of staining was stronger at the synaptic regions. However, when sections were treated with several digestive agents prior to lectin application, the lectin staining pattern changed dramatically. Collagenase-sensitive GlcNac, Mannose, Sialic acid, and GalNac-containing glycoconjugates associated with synaptic regions but not present extrasynaptically were revealed after chemical treatment. On the basis of these modifications it is proposed that, apart from the synapse-specific Gal-Nac-containing glycoconjugate already described elsewhere, new carbohydrate-containing compounds are evidenced. These results provide a new insight into regional specialization of the extracellular matrix associated with the neuromuscular junctions and indicates that pretreatment with various agents, not necessary digestive substances, may alter molecular properties of muscle membrane and uncover previously unknown binding sites.     

Characterization, fate, and function of hamster cortical granule components

Little is known about the composition and function of mammalian cortical granules. In this study, lectins were used as tools to: (1) estimate the number and molecular weight of glycoconjugates in hamster cortical granules and show what sugars are associated with each glycoconjugate; (2) identify cortical granule components that remain associated with the oolemma, cortical granule envelope, and/or zona pellucida of fertilized oocytes and preimplantation embryos; and (3) examine the role of cortical granule glycoconjugates in preimplantation embryogenesis. Microscopic examination of unfertilized oocytes revealed that the lectins PNA, DBA, WGA, RCA(120), Con A, and LCA bound to hamster cortical granules. Moreover, LCA and Con A labeled the zona pellucida, cortical granule envelope, and plasma membrane of fertilized and artificially activated oocytes and two and eight cell embryos. Lectin blots of unfertilized oocytes had at least 12 glycoconjugates that were recognized by one or more lectins. Nine of these glycoconjugates are found in the cortical granule envelope and/or are associated with the zona pellucida and plasma membrane following fertilization. In vivo functional studies showed that the binding of Con A to one or more mannosylated cortical granule components inhibited blastomere cleavage in two-cell embryos. Our data show that hamster cortical granules contain approximately 12 glycoconjugates of which nine remain associated extracellularly with the fertilized oocyte after the cortical reaction and that one or more play a role in regulating cleavage divisions.     

Lectin binding reveals divergent carbohydrate expression in human and mouse Peyer's patches

The nature of cell-associated carbohydrates in the human intestine that may mediate transepithelial transport of bacterial and dietary lectins and their processing by the lymphoid cells of Peyer's patches is not known. Because the cell surface carbohydrate receptors for lectins may vary in different species, the glycoconjugates of human and mouse follicle-associated epithelium and gut-associated lymphoid tissue were compared. A panel of 27, mainly recently isolated, lectins were used to identify glycoconjugate expression in M-cells, enterocytes, goblet cells, lymphocytes and macrophages in mouse and human intestine. Mouse M-cells were exclusively labelled by fucose-specific lectins but in human follicle-associated epithelium no distinct M-cell staining pattern was observed. In the human Peyer's patches,Bryonia dioica lectin bound selectively to paracortical T-lymphocytes andChelidonium majus lectin to germinal centre B-cells. Certain mannose-specific lectins (Galanthus nivalis, Hippeastrum hybrid) stained the tingible body macrophages in the germinal centre of human Peyer's patches but labelled the macrophages in the paracortical T-cell region of the mouse. The results indicate distinct differences in glycosylation between mouse and human Peyer's patches and their associated lymphoid cells. When considering cell surface glycoconjugates as target molecules for the gut immune system, care has to be taken to choose the appropriate lectin for each species.     

Characterization of the Carbohydrate Chain on the Substance P Receptor in the Rat Brain Cortex: Effect of Lectins on [3H]Substance P Binding

The characteristics of the carbohydrate chain on the rat cerebral cortical substance P (SP) receptor were studied. We examined the effects of pretreatment with three lectins (concanavalin A, wheat germ agglutinin, lens culinaris agglutinin) on the [3H]SP binding activities. Each lectin can bind to the specific carbohydrate chain. Among these lectins, only concanavalin A inhibited specific [3H]SP binding by reducing the affinity of the binding sites. The inhibitory action of concanavalin A was dose-dependent and diminished by the addition of alpha-methyl-D-mannoside. The present results suggest that the rat cortical SP receptor has either a biantennary complex-type or a high mannose-type of carbohydrate chain, and that the carbohydrate chain is implicated in the SP binding activity of the SP receptor system.