Distribution of lectin binding glycoprotein in osteoclasts

Summary Arachis hypogaea (PNA) lectin, specific for Gal-B-1, 3-GalNac disaccharide and Wheat germ (WGA) lectin, specific for (GlcNac) and terminal neuraminic acid were used to identify histiocytic giant cells, osteoclast like giant cells and osteoclasts. PNA lectin, without neuraminidase predigestion was not bound by the giant cells, while they showed a strong reaction with WGA lectin. Neuraminidase pretreatment decreased WGA lectin binding, which supports that neuraminic acid plays a role in the binding of WGA. On the other hand, neuraminidase digestion liberated large amounts of PNA binding sites in every type of giant cells examined, showing a strong, intracytoplasmic granular staining. This observation is indicative of presence of PNA binding sites masked by neuraminic acid. Instead of the intracytoplasmic PNA binding in some osteoclasts a well defined part of the cytomembrane was havily stained. We suppose that this PNA binding part of cytomembrane equals to the zone of resorption, characterized by the ruffled border of osteoclasts. Our findings indicate that a neuraminic acid substituted PNA binding glycoprotein is synthetized both in osteoclasts and histiocytic giant cells which may indicate a common origin of these cell types.     

Wheat germ agglutinin and other selected lectins increase synthesis of decay-accelerating factor in human endothelial cells.

Decay accelerating factor (DAF) is a cell-surface phosphatidylinositol-anchored protein that protects the cell from inadvertent complement attack by binding to and inactivating C3 and C5 convertases. We have measured DAF on human umbilical vein endothelial cells (HUVEC) by immunoradiometric assay after its removal by phosphatidylinositol-specific phospholipase C or Nonidet P-40 detergent extraction and have previously demonstrated that DAF synthesis can be stimulated by phorbol ester activation of protein kinase C. We now report that although stimulation (4-48 h) of HUVEC with various cytokines, including TNF, IL-1, and IFN-gamma, did not alter DAF levels, wheat germ agglutinin (WGA) (5-50 micrograms/ml), a lectin specific for binding N-acetyl neuraminic acid and N-acetyl glucosamine residues, increased DAF levels fivefold when incubated with HUVEC for 12 to 24 h. The lectins Con A and PHA also stimulated DAF expression twofold, whereas a number of others including Ulex europaeus, Bandeiraea simplicifolia lectin I, and Ricinus communis agglutinin I, which bind to endothelial cells, were inactive. The increase in DAF by WGA was inhibited by N-acetyl glucosamine (10-50 mM) but by neither N-acetyl neuraminic acid nor removal of surface N-acetyl neuraminic acid with neuraminidase. However, succinylated WGA, which has unaltered affinity for N-acetyl glucosamine but not longer binds N-acetyl neuraminic acid, was inactive. These data suggest that the binding of WGA to sugar residues alone is not sufficient to trigger DAF expression and that occupation of additional, specific sites are required. The increase in DAF levels on HUVEC was blocked by inhibitors of RNA and protein synthesis. We conclude that continuous occupation by WGA of specific binding sites on HUVEC triggers events leading to DAF synthesis. This unique, long term stimulation of endothelial cells by lectins may be relevant to cell:cell interactions at the endothelium.     

Characterization of glycoconjugates of human gastrointestinal mucosa by lectins. I. Histochemical distribution of lectin binding sites in normal alimentary tract as well as in benign and malignant gastric neoplasms

Labeled lectins with binding specificity to the hexose components of mucus glycoproteins (HPA, RCA I, PNA, Con A, WGA, and UEA I) were used to demonstrate structural differences in the glycoprotein composition of various cell types of the normal, benign and malignant gastrointestinal mucosa. While in the RCA I, UEA I, and WGA binding of normal mucus secreting cell types only quantitative differences were observed, the mucus in the surface epithelial cells of gastric mucosa and in the colonic goblet cells was characterized by the absence of PNA, Con A, and PNA, HPA binding sites, respectively. These lectins, however, showed a strong binding to the supranuclear, Golgi-region in the undifferentiated or activated forms of these cells. Even the staining intensity of the luminal membrane surfaces of the non mucinous parietal and chief cells was often stronger by PNA, HPA, and RCA I lectins than that of the mucus secretions in the highly differentiated mucus cells. These results indicate the existence of either heterogeneous glycoprotein components or mucus molecules with variations in the degree of glycosylation of their oligosaccharide chains in the different cells. The latter seems more likely since in benign and malignant alterations lectin binding sites appear in great density, which were found to be characteristic of the undifferentiated mucus cells or for the non mucinous cells of the normal gastric mucosa. Similarly in some gastric cancers which do not stain with the periodic acid-Schiff reaction at all, large amount of free or neuraminic acid substituted PNA binding sites can be detected.     

Modulation of endothelial cell surface glycoconjugate expression by organ-derived biomatrices

Cell surface molecules play an important role in cellular communication, migration, and adherence. Here, we show the effect of organ-derived biomatrices on endothelial cell surface glycosylation. Five different lectins (with and without neuraminidase treatment) have been used as probes in an enzyme-linked lectin assay to quantitatively detect glycoconjugates on endothelial cells (BAEC) grown on tissue culture plastic or biomatrices isolated from bovine lung, liver, and kidney. BAEC generally exhibit strong binding of concanavalin A (Con A), Ricinus communis agglutinin I (RCA-I), wheat germ agglutinin (WGA), and soybean agglutinin, and peanut agglutinin after neuraminidase pretreatment of cells (Neu-SBA and Neu-PNA), while SBA and PNA consistently bind weakly to BAEC. BAEC grown on organ-derived biomatrices exhibit significantly altered binding intensities of Con A, RCA-I, WGA, and Neu-PNA: BAEC cultured on lung- or kidney-derived biomatrices express significantly stronger binding affinities for Con A and RCA-I than BAEC grown on liver-derived biomatrix or tissue culture plastic. In contrast, BAEC binding of WGA and PNA (after treatment of cells with neuraminidase) is significantly reduced when BAEC are grown on liver- or kidney-derived biomatrix. Quantitative lectin immunogold electron microscopy reveals consistently stronger lectin binding over nuclear regions compared to junctional regions between neighboring cells. These results indicate that extracellular matrix components regulate endothelial cell surface glycoconjugate expression, which determines cellular functions, e.g., preferential adhesion of lymphocytes or metastatic tumor cells.     

Lectin histochemistry of epidermal glandular cells in the earthworm Lumbricus terrestris (Annelida Oligochaeta)

Carbohydrate residues were localized in the glandular cells of the epidermis of Lumbricus terrestris by lectin histochemistry. The following biotinylated lectins were used: ConA, PNA, WGA, UEA-I. Each lectin has a specific binding pattern in the epidermal glandular cells. The ConA binding is evident in the orthochromatic mucous cells; PNA in the metachromatic mucous cells; WGA in the neuroendocrine-like cells; UEA-I in the cuticle. The epidermal glandular cells possess specific sites for the different lectins in relation to their functional characteristics. Therefore, these sugar residues indicate different behaviours of the cells in epidermal functions related to ion transport, receptor-secretory processes and defence.     

Characterization of carbohydrates of adult Echinococcus granulosus by lectin-binding analysis

The identification of lectin-binding structures in adult worms of Echinococcus granulosus was carried out by lectin fluorescence; the distribution of carbohydrates in parasite glycoconjugates was also studied by lectin blotting. The lectins with the most ample recognition pattern were ConA, WGA, and PNA. ConA showed widespread reactivity in tegument and parenchyma components, including the reproductive system, suggesting that mannose is a highly expressed component of the adult glycans. Although reproductive structures appeared to be rich in N-acetyl-D-glucosamine (GlcNAc)-N-acetyl neuraminic acid (NeuAc) and galactose (Gal) as demonstrated by their strong reactivity with WGA and PNA, respectively, some differences were observed in their labeling patterns. This was very clear in the case of the vagina, which only reacted with WGA. Furthermore, WGA and ConA both had reactivity with the excretory canals. RCA, the other Gal binding lectin used, only reacted with the tegument, suggesting that widespread PNA reactivity with the reproductive system is related to the presence of the D-Gal-beta-(1,3)D-GalNAc terminal structure. UEA I failed to bind to any parasite tissues as determined by lectin fluorescence, whereas DBA and SBA showed a very faint staining of the tegument. However, in transferred glycans, N-acetyl-D-galactosamine (GalNAc) and fucose (Fuc) containing glycoproteins were distinctly detected.     

Binding of wheat germ agglutinin to extracellular network produced by cultured human fibroblasts

The occurrence of diverse carbohydrate moieties on the cell surface and in the extracellular matrix, makes lectins the suitable probes to study the distribution of appropriate determinants produced in cell culture. Biotin-labelled wheat germ agglutinin (WGA) was used in microscopic and photometric detection of lectin binding to monolayer of human skin fibroblasts. The incubation of confluent fibroblast monolayer with labelled WGA reveals two principal patterns of binding of this lectin: to cell surface structures and, predominantly, to extracellular fibres; the alignment and density of extracellular network are not uniform. After binding of WGA to confluent culture, light microscopic analysis revealed the ubiquitous fibrillar network between and over cells, with some regions of increased compactness and altered orientation of fibrils. Binding to cell surfaces (manifested as specks) was predominant for the fibroblasts at the logarithmic phase of growth. N-acetylglucosamine (0.2 M) and native lectin (100 microg/ml) had a partial inhibitory effect on WGA binding to the extracellular network. Treatment with neuraminidase (0.1 unit/ml) of untreated or prefixed monolayers resulted in a significant decrease in WGA binding to fibrils (and increase in PNA binding), indicating that terminal sialic acid residues are mainly involved in the network-WGA interaction. Mild trypsinization (10 microg/ml) removed the target sites, which retained the ability to bind WGA, being spotted on hydrophobic Immobilon P paper; biotinylated lectin, bound to adsorbed glycopeptides, could be eluted and quantified in solid-phase inhibition assay.     

Lectin binding sites in normal and phenobarbitale/halothane treated rat liver. A histochemical study

The content of carbohydrate residues of both normal and phenobarbitale-halothane-hypoxia exposed rat liver has been examined by means of lectin histochemistry. Eight biotinylated lectins specific to galactose, N-acetyl-galactosamine, N-acetyl-glucosamine, fucose and mannose were applied to paraffin sections of rat liver at light microscopic level. The most distinct binding was observed at the structures of the "perisinusoidal functional unit": Kupffer cells are bound by S-WGA, SBA and PNA. Bile canaliculi display binding sites for RCA I and WGA. Cytoplasm of hepatocytes appears lectin-negative, except for PSA. The enhanced reaction of S-WGA, PNA and SBA after the preincubation of the sections with neuraminidase indicates the occurrence of sialic acid in Kupffer cells. The phenobarbitale-halothane-hypoxia exposed rat liver shows centrolobular degeneration of hepatocytes with a diminished amount of hepatocyte and Kupffer cells as well. The lectin binding pattern of sinusoidal walls, membranes of hepatocytes and bile canaliculi remains the same compared to that of normal rat liver. This finding suggests that at least the carbohydrate content of membranes in the liver resists severe destruction under phenobarbitale-halothane-hypoxia. It is assumed that there exists a connection between intact carbohydrate residues and the regeneration of liver parenchyma.     

Effect of thyroid hormones on the histotopography of lectin receptors in the rat salivary gland

Using lectin-peroxidase technique, the influence of hypo- and hyperthyroidism on histotopography of glycoconjugates has been investigated in rat submandibular gland. The following lectins were used: peanut agglutinin (PNA), wheat germ agglutinin (WGA), Laburnum anagyroides lectin (LAL) and concanavalin A (con A). It has been demonstrated that hyperthyroidism is accompanied by the loss of con A, WGA and LAL receptor sites. Hypothyrodism enhanced con A binding to granular duct cells with a parallel reduction in WGA and LAL binding to these or other duct cells. Hypothyroidism as well as hyperthyroidism markedly enhanced PNA binding to duct epitheliocytes with redistribution of these lectin binding sites from the luminal surface of salivary ducts into the cytoplasm of duct cells. Possible interpretations of the observed phenomena are discussed.     

Differences in lectin binding in squamous metaplasia induced by benzo(a)pyrene and vitamin A deficiency in hamster tracheal explants

Summary Epidermoid metaplasia in the hamster trachea can be produced by treatment with benzo(a)pyrene (BP) or vitamin A deficiency. To elucidate distinguishing features of the two types of lesions, lectin binding to tissue sections of tracheal explants exhibiting metaplastic lesions was assessed. In squamous metaplasia induced by vitamin A deficiency, Dolichos biflorus agglutinin (DBA), wheat germ agglutinin (WGA), and peanut agglutinin (PNA) showed faint (+) to moderate (++) binding in both basal and suprabasal cells; Concanavalin A (Con A) showed moderate binding (++) to suprabasal cells and no binding in basal cells. In the BP-induced lesions, PNA and WGA bound intensely (++++, +++, respectively) in basal cells and faintly (+) to moderately (++) in suprabasal cells. The staining seemed to be predominant at the periphery of the cells. Further, the intensity of PNA and WGA staining increased significantly after the neuraminidase treatment. DBA and Con A showed faint (+) to moderate (++) binding in the BP-induced metaplasia. The results show that in BP-induced metaplasia, cells in the basal region show preferential binding of PNA and WGA. This research was supported by grant RO1-HL32308 from the National Heart, Lung and Blood Institute, Bethesda, MD.     

Accumulation of anomalous glycopolymers in the walls of main lymphatic vessels of the extremities in patients with chronic lymphedema

Redistribution of lectin receptor sites in the mam-lymphatics of human extremities in primary and secondary lymphedema in comparison with normal lymphatics has been investigated using conjugates to peroxidase of LCA, PNA, RCA, SBA, WGA and LAA. Chronic lymphedema caused no essential differences in lectin binding to tissue structures of intima and adventitia: endotheliocytes were strong reactive both with LCA, PNA, WGA and LAA; all lectins used bound fibrillary structures in subendothelial layer and adventitia. On the opposite, tunica media of main lymphatics in primary lymph stasis displayed accumulation of LCA-, PNA-, SBA- and LAA-binding deposits round smooth myocytes. When PNA used, the appearance of a specific "wide loop shaped reticulum" within lymphatics media in lymph stasis was observed. We consider, that lectin receptor sites accumulation phenomenon reflects some changes in smooth myocytes metabolism, possibly caused by dystrophia of these cell population with consequent incomplete glycosylation of synthesized glycopolymers.     

Localization of glycoconjugates on the surfaces of pronephric tumor cells in vitro

Differential localization of glycoconjugates was detected on microvilli and microridges of the intact cell surface of frog pronephric tumor cells in tissue culture. Alcian blue and Alcian blue/PAS staining showed a heavy concentration of dye limited to the unique short microvilli and extensive microridges of the tumor cells as previously seen with SEM (Tweedell and Williams 1976). Staining was absent or greatly reduced on microvilli of the normal pronephric cell surface. Previous exposure of each kind of cells to neuraminidase or extraction by mild hydrolysis removed the active staining sites but Alcian blue uptake was unaffected by prior digestion with testicular hyaluronidase. Fluorescein isothiocyanate (FITC) bound wheat germ agglutinin (WGA) produced a similar pattern of fluorescence on the microvilli of the tumor cells and a limited distribution on the normal cells. Digestion with neuraminidase preferentially removed but did not completely eliminate the surface binding of WGA on both the normal and tumor cells. Exposure of tumor cell monolayers to FITC bound limulin, a lectin specific for sialic acid, also produced an intense surface fluorescence on the microvilli and ridges of tumor cells. Prior treatment with neuraminidase prevented the surface fluorescence but not internal binding. Normal pronephric cells gave sparse surface fluorescence but extensive internal binding. Each procedure indicates a preferential localization of complex carbohydrates, including sialic acid, on the unique microvilli of the tumor cells. Concurrent assays for sialic acid recovered from the tumor cells indicated that lectin bound surface sialic acid was removable with neuraminidase.     

Effects of retinoic acid on the distribution of glycoconjugates during mouse tail bud development

Retinoic acid (RA), a potent teratogen of caudal axial development in rodents, has been shown to alter glycoconjugates in a variety of embryonic tissues and teratocarcinomas. In this study, we examined its effects on the expression of cell surface and extracellular matrix glycoconjugates during tail bud development in mouse embryos by using lectin histochemistry. The lectins WGA, sWGA, and PNA showed striking differences in binding between RA-exposed and control embryos. Computer-assisted densitometry revealed a significant increase in binding of all three lectins to the extracellular material of the luminal and abluminal borders of the secondary neural tube and surrounding the notochord in RA-exposed embryos. RA-treated embryos also showed an increased binding affinity for the lectins sWGA and PNA to the cells of the notochord, while WGA showed increased binding to the neuroepithelial cells of the secondary neural tube. The results suggest that RA affects the expression of lectin binding sites during the early development of RA-induced caudal axial defects.     

Localization of glycoconjugates on the surfaces of pronephric tumor cells in vitro

Summary Differential localization of glycoconjugates was detected on microvilli and microridges of the intact cell surface of frog pronephric tumor cells in tissue culture. Alcian blue and Alcian blue/PAS staining showed a heavy concentration of dye limited to the unique short microvilli and extensive microridges of the tumor cells as previously seen with SEM (Tweedell and Williams 1976). Staining was absent or greatly reduced on microvilli of the normal pronephric cell surface. Previous exposure of each kind of cells to neuraminidase or extraction by mild hydrolysis removed the active staining sites but Alcian blue uptake was unaffected by prior digestion with testicular hyaluronidase. Fluorescein isothyocyanate (FITC) bound wheat germ agglutinin (WGA) produced a similar pattern of fluorescence on the microvilli of the tumor cells and a limited distribution on the normal cells. Digestion with neuraminidase preferentially removed but did not completely eliminate the surface binding of WGA on both the normal and tumor cells. Exposure of tumor cell monolayers to FITC bound limulin, a lectin specific for sialic acid, also produced an intense surface fluorescence on the microvilli and ridges of tumor cells. Prior treatment with neuraminidase prevented the surface fluorescence but not internal binding. Normal pronephric cells gave sparse surface fluorescence but extensive internal binding. Each procedure indicates a preferential localization of complex carbohydrates, including sialic acid, on the unique microvilli of the tumor cells. Concurrent assays for sialic acid recovered from the tumor cells indicated that lectin bound surface sialic acid was removable with neuraminidase.This study was supported by a grant from the Cancer Society of Saint Joseph County, Indiana and from the Phi Beta Psi Sorority     

Postnatal development of lectin binding sites in the rat ventral prostate

Summary Five Fluorescein-isothiocyanate (FITC)-labelled lectins were used to study the postnatal development of carbohydrate constituents in the rat ventral prostate: Concanavalin A (Con A), wheat germ agglutinin (WGA), peanut agglutinin (PNA),Dolichos biflorus agglutinin (DBA) andRicinus communis agglutinin I (RCA-I) With all the lectins, tested, except RCA-I, specific binding sites could be shown for every stage of differentiation in the glandular epithelium. Binding sites for Con A, WGA, PNA and DBA were found from day 10 to 13 post partum onwards. Each lectin showed a characteristic localization. Binding sites for the lectins used changed to different extents during the following two weeks. After the 24th day post partum no further changes in the lectin binding pattern could be found. The development of the lectin binding properties showed that the changes in carbohydrate-containing constituents of the prostate correlate with the beginning of prostatic secretion and to prostatic epithelial differentiation. In the periacinar stroma the development of the lectin binding pattern was similar to that in the glandular epithelium. The changes of stromal binding sites for Con A and WGA during epithelial differentiation may reflect the changes of epithelial-stromal interactions in the prostate.     

Spatial and temporal changes in the pattern of glycosylation of the developing chick limb tissue components as revealed by fluorescent conjugated lectin probes

The changing pattern of expression of glycoconjugates during the differentiation of the chick leg bud between stages 17 to 34 (days 3 to 8 of incubation) was studied using fluorochrome-labelled plant lectins. Limb buds were fixed in cold acetic-alcohol and wax-embedded. Agglutinins of peanut (PNA), soybean (SBA) and succinylated wheat germ (WGAs) revealed a specific binding pattern in the apical ectodermal ridge (AER) between Hamburger and Hamilton stages 19-32. These stages coincide with the period of elevation of the AER. This specific binding pattern was absent from the adjacent dorsal and ventral ectoderm. Prechondrogenic cells were positive for WGA and for PNA, and the PNA-binding capacity was intensified after neuraminidase treatment. Premyogenic cells at stage 23 can be identified as negative to PNA after neuraminidase, while the blood vessels became positive. PNA, SBA, WGA, WGAs and, in addition, Ricinus communis (RCA-I) lectins stained the basal membrane. Strands of extracellular matrix which connect with the basal membrane and cross the limb transversely between dorsal and ventral ectoderm were stained by RCA-I, SBA and PNA after neuraminidase.     

Membrane-bound glycoconjugates of fetal mouse erythropoietic cells with special reference to phagocytosis by hepatic macrophages

Using lectin and colloidal iron (CI) stainings in combination with neuraminidase digestion, glycoconjugates on the surface of erythropoietic cells of the yolk sac and liver in fetal mice were examined. Fetal hepatic macrophages were capable of distinguishing between phagocytozed and non-phagocytozed erythroid elements as described in our previous study. Marked differences between these two elements could be ultrahistochemically detected on their cell surface. The phagocytozed elements, such as nuclei expelled from erythroblasts and degenerating primitive erythroblasts, faintly bound neuraminidase-sensitive CI, and neuraminidase digestion imparted a weak peanut agglutinin (PNA) binding. In contrast, erythroblasts at various maturation stages, erythrocytes and normal primitive erythroblasts heavily bound neuraminidase-sensitive CI, and neuraminidase digestion imparted a moderate PNA binding. No differences in binding of either concanavalin agglutinin,Ricinus communis agglutinin-I or PNA were noted between phagocytozed and non-phagocytozed erythroid elements. Desialylation appears to be one of the most important signs for the recognition mechanism of fetal macrophage phagocytosis. During maturation of hepatic erythroblasts, sialic acid changes its affinity forLimax flavus agglutinin from strong to weak, and soybean agglutinin binding sites disappear at the basophilic erythroblast stage. Glycoconjugates on polychromatophilic erythroblasts acquire similar compositions to those of erythrocytes.     

A biotechnological tool for glycoprotein desialylation based on immobilized neuraminidase from Clostridium perfringens

BackgroundSialic acids are widely distributed in nature and have biological relevance owing to their varied structural and functional roles. Immobilized neuraminidase can selectively remove terminal N-acetyl neuraminic acid from glycoproteins without altering the protein backbone while it can be easily removed from the reaction mixture avoiding sample contamination. This enables the evaluation of changes in glycoprotein performance upon desialylation.MethodsNeuraminidase was immobilized onto agarose activated with cyanate ester groups and further used for desialylation of model glycoproteins, a lysate from tumour cells and tumour cells. Desialylation process was analysed by lectin binding assay, determination of sialyl-Tn or flow cytometry.ResultsClostridium perfringens neuraminidase was immobilized with 91 % yield and expressed activity yield was of 41%. It was effective in the desialylation of bovine fetal serum fetuin, bovine lactoferrin and ovine submaxilar mucin. A decrease in sialic-specific SNA lectin recognition of 83% and 53 % was observed for fetuin and lactoferrin with a concomitant increase in galactose specific ECA and PNA lectin recognition. Likewise, a decrease in the recognition of a specific antibody (82%) upon mucin desialylation was observed. Moreover, desialylation of a protein lysate from the sialic acid-rich cell line TA3/Ha was also possible leading to a decrease in 47 % in SNA recognition. Immobilized neuraminidase kept 100% of its initial activity upon five desialylation cycles.ConclusionsImmobilized neuraminidase is an interesting as well as a robust biotechnological tool for enzymatic desialylation purposes.General significanceImmobilized neuraminidase would contribute to understand the role of sialic acid in biological processes.     

Lectin binding and inhibition studies reveal the importance of D-glucose, D-mannose and N-acetylglucosamine during early sexual development of Dictyostelium discoideum

Fluorescein-conjugated and non-conjugated lectins were used to determine which surface sugars are involved in the early events of sexual (macrocyst) development in Dictyostelium discoideum. Only zygote giant cells showed unique binding of FITC-WGA and FITC-PNA while all cell types (amoebae, gametes, binucleates, giant cells) showed identical patterns of FITC-Con A, -Gorse and -RCA II binding. In spite of its non-selective labelling of all cell types, Con A inhibited macrocyst formation. The temporal addition of Con A with and without specific hapten sugars indicates the importance of both D-mannose and D-glucose in phagocytosis and, possibly, cell fusion. WGA also inhibited macrocyst formation. Varying the time of addition of the lectin plus/minus its primary hapten sugar implicates N-acetylglucosamine as being important in cell fusion. Neither Gorse, RCA II nor PNA had any detectable inhibitory effects on macrocyst development leaving the appearance of increased PNA receptors at the giant cell surface as an enigma.     

Lectin binding by structures of the submandibular gland of the rat during postnatal ontogenesis in the presence of thyroid pathology

Redistribution of lectin receptor sites in rat submandibular gland under hypo- and hyperthyroidism has been investigated using lectin-peroxidase technique. Lectin preparation include con A, peanut agglutinin (PNA), wheat germ agglutinin (WGA) and fucose-specific lectin from Laburnum anagyroides bark (LAB). Submandibular gland is excised on the 1st, 10th, 20th and 40th days of postnatal life and in adult rats. Hyperthyroidism, as well as hypothyroidism cause a considerable decrease of con A, WGA and LAB binding with simultaneous enhancement of PNA binding in all investigated groups of the animals. The only exception from this regularity is noted for con A: hypothyroidism in adult rats and on the 40th day of postnatal development causes enhancement of this lectin binding to granular duct epitheliocytes. Selective staining of mast cells with PNA and of separate neurocytes with con A is also demonstrated; these cells staining is affected neither by hyperthyroidism, nor by hypothyroidism. Possible interpretation of the observed phenomena is discussed.