Histological detection of lectin binding sites in human gastrointestinal mucosa

Pepsinogen and H,K-ATPase mediate acid secretion in gastric glands of Triturus carnifex (Amphibia, Caudata)

The gastric glands of Triturus carnifex (Amphibia, Caudata) have been examined by histochemical and immunohistochemical methods with particular regard to hydrochloric acid and pepsinogen secretion. Fundic glands consist of mucous neck cells, endocrine cells and oxynticopeptic cells producing both pepsinogen and hydrochloric acid. The neck cells showed an unexpected distribution pattern which was only observed in the oral fundus, and produced neutral mucins with glycosidic residues of GalNAc and Gal beta1,3GalNAc, and in this respect they differ from the neck cells of anuran amphibians. The secretion of pepsinogen and hydrochloric acid as demonstrated by immunolabelling with anti-H,K-ATPase and with anti-pepsinogen, respectively, seems not to vary significantly along the longitudinal axis of the stomach. The mechanism of gastric acid secretion seems to be mediated by an ATPase, having similar features to the mammalian gastric H,K-ATPase, and is localised in the luminal membrane and in the subapical cytoplasm of the oxynticopeptic cells. Unusually, the same cytoplasmic areas revealed binding specificity for the winged pea lectin (WPA) from Lotus tetragonolobus, even after beta elimination, indicating the presence of fucosyl residues in N-linked oligosaccharidic chains in glycoproteins of beta-H,K-ATPase subunits.

Histochemical investigations on the secretory cells in the oesophagogastric tract of the Eurasian green toad, Bufo viridis

The secretory cells of the oesophagogastric tract of the Eurasian toad, Bufo viridis, were examined using standard histochemical methods and lectin histochemistry. Two goblet cell types were found in the oesophageal epithelium, differing in their morphology and the histochemical features of the secretory granules. These contained mainly acidic glycoconjugates, both sulphated and carboxylated, and a small amount of pepsinogen. Type I goblet cells contained stable class-III mucosubstances, which were absent in Type II. No pluricellular oesophageal glands were found. The oesophagogastric junction had a superficial epithelium similar to that of the oesophageal epithelium, with alveolar pluricellular glands, secreting stable class-III mucins, and few oxynticopeptic cells. The gastric mucosa presented secretory cells both in the surface epithelium and in the gastric glands. Superficial and foveolar cells produced neutral mucins with Gal(beta)1,3GalNAc residues. Neck cells, oxynticopeptic cells and endocrine cells were found in the gastric glands. Neck cells produced stable class-III mucosubstances. A functional gradient was observed in the oxynticopeptic cells from the oral to the aboral fundus, with a decrease in pepsinogen secretion towards the aboral fundus and a possible increase in HCl secretion. In the pyloric mucosa, the oxynticopeptic cells disappeared and the glands produced only neutral mucins, without stable class-III mucosubstances.

Light and electron microscopic investigation of the lectin-binding pattern in the oxyntic gland region of bovine abomasum

For the first time the expression of glycoconjugate residues in the oxyntic gland region of bovine abomasum has been investigated by means of lectin histochemistry. For light microscopic investigations, a battery of ten lectins, Con A, PSA, UEA I, WGA, LEA, SNA, RCA120, MPA, DBA and SBA was used. For electron microscopic examinations, WGA and RCA120 were utilized. The staining pattern of the lectins in all exocrine cell types of the oxyntic gland region is described. Compared to the results of monogastric species our study reveals some similarities, but just as many differences in the composition of glycoconjugate residues in bovine exocrine cell types. Typical for surface mucous cells is the amount of L-fucose, N-acetyl glucosamine residues and Galbeta1, 4GlcNAc sequences in the secretory granules. SNA could serve as a marker for surface mucous cells, because this lectin exclusively stains the plasma membrane and the secretory granules of surface mucous cells and the extracellular mucus. L-fucose and N-acetyl glucosamine are typical for the secretory granules of mucous neck cells. In addition, the secretory granules show the highest amount of N-acetyl galactosamine residues of all exocrine cells, so that DBA and SBA are recommended as marker lectins for mucous neck cells. Most lectins strongly stain the intracellular membrane system of oxyntic cells. The cocktail of glycoconjugates in the vicinity of the HCI production site provide protection against chemical injury. In chief cells only the apical plasma membrane is more or less labeled with all lectins apart from SNA. Specific marker lectins for oxyntic cells or chief cells of the bovine have not been characterized.

Concomitant staining of mast and parietal cells in human gastric mucosa

A simple technique for concomitant staining of mast and parietal cells in the same section is described. Mast cells were stained by alcian blue or astra blue in methanol-formalin-acetic acid fixed biopsies of gastric mucosa. Parietal cells were visualized by Dolichos biflorus lectin binding.

Ultracytochemistry of glycoconjugates in pig duodenal gland

To elucidate the ultrastructure, glycoprotein profile and site of glycosylation of glandular cells in relation to the functional polarity of the organelles, swine duodenal tissue was embedded in glycol methacrylate and subsequently stained for periodic acid thiocarbohydrazide silver proteinate (PA-TCH-SP), high iron diamine (HID)-TCH-SP, low iron diamine (LID)-TCH-SP, ninhydrin T-TCH-SP and five peroxidase-labeled lectins. The secretory granules in the duodenal gland cells were electron lucent with a 200 nm to 500 nm electrondense core. Glycoconjugates were confined to the secretory granules and elements of the Golgi complex. Protein activity was located only in the electron dense core. Achivementestic staining pattern for Concanavalin A (Con A), peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I), wheat germ agglutinin (WGA) and soybean agglutinin (SBA) was observed in stained secretory granules and the Golgi apparatus. A few cis cisternae were stained with SBA and UEA-I. Trans cisternae were stained with WGA and PNA. Con A reacted with seromucous granules and rough endoplasmic reticulum. These observational findings suggest that these are seromucous cells. The Golgi apparatus is the site of glycosylation and can be divided into two distinct compartments.

Isolation, identification and quantitative evaluation of specific cell types from the mammalian gastric mucosa

Functional in vitro studies with isolated gastric mucosal cells require cytological identification of different cell types in suspension or primary culture. Since suitable techniques have not been well established, different staining methods for the discrimination of dispersed pig and guinea pig gastric cells have been developed on the basis of modified previous protocols for enzymatic cell dispersion. Chief and parietal cells were visualized by combined periodic acid-Schiff stains. Surface mucous and mucous neck cells were identified by affinity-labelling, using lectins with selective staining properties in situ. Two of the lectins were found to be specific markers for gastric polymorphonuclear cells. The following vital tests were found to be useful: succinic dehydrogenase for parietal cells, Nile blue/brilliant cresyl blue stains for chief cells, and different phagocytosis assays for endothelial cells and gastric phagocytes. Endocrine cells were characterized by immunocytochemistry using specific antibodies against gastrin, somatostatin, histamine and serotonin. The same technique using a vimentin antibody was performed for the identification of fibroblasts. Proliferation of mucosal cells in primary culture was monitored by the incorporation of bromo-deoxyuridine, which was subsequently detected by a monoclonal antibody.

Studies of lectin binding to the human cervix uteri: I. Normal cervix

Lectins of Bauhinia purpurea (BPA), Canavalin ensiformis (Con A), Griffonia simplicifolia I (GS I), Griffonia simplicifolia II (GS II), Maclura pomifera (MPA), Arachis hypogaea (PNA), Glycine max (SBA), Ulex europaeus I (UEA I) and Triticum vulgaris (WGA) were used to evaluate cell surface carbohydrates in formalin-fixed paraffin-embedded tissue sections of normal human cervix uteri. Consistent patterns of staining of the squamous epithelium were obtained in all 30 cases with BPA, GS II, MPA, PNA, SBA and WGA. A variable distribution of lectin binding was seen in squamous epithelium with Con A, GS I and UEA I. The patterns of GS I and GS II binding reflected squamous epithelial maturation. Columnar epithelium did not stain with GS II, stained variably with Con A, and stained consistently with the remaining seven lectins in all cases. No association between lectin binding and blood group or phase of the menstrual cycle was found. These findings may be used as a baseline for evaluation of lectin binding in both preinvasive and invasive lesions of the cervix uteri.

Lectin-induced damage to the enterocyte brush border. An electron-microscopic study in rabbits

The ultrastructural effects of 11 lectins on the intestinal brush border were examined by means of an in vitro rabbit ileal mucosal explant culture system. Five of the lectins that bind to oligosaccharides containing either N-acetylglucosamine (phytohaemagglutinin, Euonymus europaeus lectin, pokeweed mitogen, and wheat germ agglutinin) or N-acetylneuraminic acid (Mycoplasma gallisepticum lectin) all had a specific effect on microvilli. The effects varied in accordance with the lectin and included lengthening, distortion, and vesiculation of the microvilli. In contrast, lectins binding specifically to galactose, glucose, mannose, and N-acetylgalactosamine had no effect. Incubation of mucosal fragments with the divalent cation ionophore A23187 did not mimic the effect of the lectins. This apparent relationship between lectin damage and receptor specificity may reflect either accessibility of appropriate binding sites or a differential response to binding.

Carbohydrate histochemistry of human Brunner's glands

Brunner's glands are known to produce neutral mucins. In order to achieve a better knowledge of their carbohydrate profile, we used five peroxidase-labeled lectins on surgical specimens of human duodenum. This method allowed us to identify at least two different types of neutral mucins in Brunner's glands secretion, thus demonstrating a heterogeneous mucin production. The structure of terminal oligosaccharidic chains in these glycoproteins has also been hypothesized.

Fucose-containing antigens in normal and neoplastic human gastric mucosa: a comparative study using lectin histochemistry and blood group immunohistochemistry

The histochemical binding to normal and neoplastic human gastric mucosa of two lectin-peroxidase conjugates which are specific for fucose-containing glycoconjugates is described. The lectins are Ulex europaeus (UEA1) and Lotus tetragonolobus (LTA). Results are compared with ABO and secretor status and the immunohistochemical demonstration of a Type 1 antigen (Lewisa) and two Type 2 antigens (X and H) using monoclonal antibodies. Binding of UEA 1 and LTA to surface mucus cells in normal gastric mucosa is only seen in secretors but is independent of ABO status. In gastric carcinomas lectin binding is reduced. There is a relationship between UEA1 binding and the immunohistochemical demonstration of H Type 2 antigen and secretor activity. In contrast LTA staining is associated with both H Type 2 and Lea antigen but not with secretor status. X antigen is only demonstrable in small amounts. Despite subtle differences in the binding patterns of the two lectins, immunohistochemical studies with monoclonal antibodies against defined oligosaccharides provide greater information. The results of the study are consistent with the hypothesis that competitive interaction between fucosyl and sialyl transferases occurs in gastric malignancy and leads to the expression of abnormal blood group-related antigens.

Alternative ultrastructural localization of Dolichos biflorus lectin binding sites in proton secreting parietal cells of mice

High amount of N-acetyl-D-galactosamine specific lectin binding sites were detected on the canalicular membranes of human parietal cells. Our present model investigations on mice showed that the intracellular distribution of the terminal N-acetyl-D-galactosamine containing glycoprotein highly depends on the actual functional state of the parietal cells. In the normal gastric mucosa 40%-60% of parietal cells react positively after staining with horseradish peroxidase or biotin labelled Dolichos biflorus lectin. Ultrastructurally lectin binding sites occur mainly on the basolateral membrane infoldings in fed animals, while they are present exclusively on the canalicular membranes of fasting mice, suggesting that the alternative appearance of lectin binding sites on the opposite membrane areas of parietal cells is tightly coupled to their main function, to H+ secretion.

Histological demonstration of wheat germ lectin binding sites in the liver of normal and ANIT treated rats

Wheat-germ lectin peroxidase conjugate was used to stain the liver of normal rats and rats given alpha-naphthylisothiocyanate (ANIT). Changes in patterns in bile duct and canalicular staining were compatible with the hypothesis that cell damage caused by ANIT is essentially restricted to bile ducts.

In vivo localization of radioiodinated peanut lectin in a murine TA3/Ha mammary carcinoma model

Peanut lectin (PNA) binds avidly to oligosaccharides containing the terminal sequence beta-D-Gal(1----3)alpha-D-GAlNAc. This disaccharide is the immunodeterminant group of the Thomsen-Friedenreich (T) antigen which is present in an exposed form on a number of human and animal adenocarcinomas and can be identified in tumor tissue sections by histochemical PNA staining techniques. We have studied the in vivo uptake of radioiodinated PNA in a murine TA3/Ha mammary adenocarcinoma model to evaluate the potential applications of radiolabeled PNA for the immunodetection of T antigen expressing carcinoma. We have found that PNA has a high in vitro binding affinity for the TA3/Ha tumor cells as well as for epiglycanin, a glycoprotein fraction shed by the TA3/Ha cells. Tissue biodistribution studies after IV 125I-PNA injection into TA3/Ha tumor-bearing mice indicated tumor:blood ratios of 7:1 and 55:1 at 24 and 48 h with corresponding tumor:muscle ratios of 33:1 and 77:1. The high tumor uptake and rapid blood clearance allowed clear scintigraphic delineation of tumor by 24 and 48 h without the necessity for background subtraction techniques. Rapid in vivo deiodination of 125I-PNA also contributed to localization of radioactivity in the stomach, salivary glands, thyroid, and kidney.

The binding of peroxidase-labelled lectins to human breast epithelium. I--Normal, hyperplastic and lactating breast

Six peroxidase-labelled lectins have been applied to tissue sections of normal, hyperplastic and lactating human breast. The effect of fixation on binding has been assessed by the comparison of specimens treated with a variety of fixatives with frozen material; the effect of trypsin has also been considered. The other objective has been to establish the consistency of lectin reactivity with this non-malignant breast tissue. Fixation has little effect on the binding of wheat germ agglutinin and peanut lectin, although reactivity with the latter was sometimes increased above that seen in frozen material by the use of Bouin's fluid. Trypsinization of formalin-fixed tissue appears to be a prerequisite for staining with soy bean agglutinin and Ulex europeus. The binding of Lotus tetragonolobus and Dolichos biflorus to fixed tissue has been found to be unreliable in comparison to frozen samples. Soy bean agglutinin and Dolichos biflorus, both specific for N-acetyl-D-galactosamine, have binding patterns which vary between specimens and often between themselves. Of the two fucose-binding lectins Ulex europeus has shown a variability of reaction between specimens, whilst Lotus tetragonolobus consistently reacts with ductal and acinar epithelium but with varying intensities. Consistent binding patterns have been found for wheat germ agglutinin and peanut lectin, the latter after the use of neuraminidase. They therefore form a useful basis for comparison with the reactivity of malignant breast tissue.