Distribution of lectin binding sites in rabbit oviduct

The carbohydrate histochemistry of the rabbit oviduct has been examined by the use of four lectins conjugated with horseradish peroxidase as histochemical reagents. Each lectin gave a very distinct typical pattern of binding, but for each lectin there was no difference between the distribution of binding sites in ampulla and isthmus. Wheat germ lectin bound exclusively with the connective tissue of the oviduct folds; winged pea lectin was detected only in the ciliated cells; peanut lectin binding sites were visualized in the secretory cells; the binding reactivity of soybean lectin was limited to the basal part of the cilia. Although it is very difficult at present to correlate the distribution of lectin binding sites with the function of the positive cells, some hypotheses have been advanced.     

Lectin binding to formalin-fixed paraffin sections.

Lectins are potentially useful tools in histopathology for the identification of carbohydrates and distinguishing cells according to their type, differentiation or function. Conjugated to fluorescent or enzyme labels, lectins are simple to use on fresh tissue but fixation and processing sequesters glycoconjugates and dissolves out fat-linked sugars. We describe here the use of labelled antibodies to lectins to localise sites of lectin binding and increase sensitivity, combined with trypsin and neuraminidase to reveal sequestered carbohydrates. Absorbing lectins with appropriate sugars establishes the specificity of binding and allows lectins to be used as sensitive and specific reagents.     

Conjunctival cell glycoprotein pattern of healthy persons and of patients with primary Sj?gren's syndrome--light microscopical investigation using lectin probes

Formalin-fixed biopsies of conjunctival tissue from the lower fornix of 10 healthy persons and of 10 patients with primary Sj?gren's syndrome (primary SS) were examined by light microscopy. Deparaffinized, rehydrated sections of 5 microns were incubated overnight, each with one of 15 different biotinylated lectins. Bound lectins were visualized using avidin-HRP-substrate complexes. Five lectins did not bind to conjunctival cells, and further six lectins bound in an unspecific manner to conjunctival cells of both healthy persons and of primary SS patients. Jacalin lectin bound selectively to goblet cells of all specimens. Peanut agglutinin (PNA) and wheat germ agglutinin (WGA) bound significantly stronger to basal conjunctival epithelial cells of patients with primary SS. This binding pattern may be of diagnostic value.     

Lectin binding characteristics of mouse placental cells

The lectin binding characteristics of mouse placental cells were examined. Wax embedded tissue sections of placentae from d 14 pregnant mice were stained with 26 lectins, with a wide range of sugar specificities. Cell cultures prepared from d 14 mouse placentae and cultured for 24 h were stained with 7 of the lectins to determine if they could be used as markers for the different trophoblast cells in culture. In tissue sections all placental cell populations bound lectin but no lectin bound specifically to any single trophoblast population. All the lectins which bound to layer 1 cytotrophoblast lining the maternal blood spaces of the labyrinthine placenta also bound to the fetal endothelium of the labyrinthine placenta. Binding of lectin appeared strongest on the adluminal membrane of these cell populations suggesting a role for the carbohydrate moieties in nutrient transfer. Few lectins bound to junctional zone trophoblast. Overall, the binding of lectin to cultured cells did not correlate exactly with lectin binding to the cell populations in tissue sections. The value of lectins as markers for placental cells in culture was therefore found to be limited. Our findings indicate that carbohydrate expression by at least some placental cells may vary in culture from that expressed by the cells in vivo with obvious concerns for the validity of functional in vitro studies.     

Human neutrophil membrane topography: examination of distribution, movement, and regeneration of recognition sites using lectins as probes

We have studied the pattern of membrane binding site redistribution, movement, and reappearance in polarized and nonpolarized human neutrophils using fluorescein and rhodamine-labeled lectins as probes. In suspension, polymorphonuclear leukocytes (PMN) were spherical and displayed a random array of recognition sites for all of the probes. PMN polarized in suspension by 10(-6) M N-formyl-L-methionyl-L-phenylalanine (f-Met-Phe), and PMN attached to substrate accumulated the bound lectin recognition site complex at the uropod (for Con A; 92.0 +/- 0.2% of cells and 91.3 +/- 9.8% of cells, respectively). Glutaraldehyde fixation of neutrophils oriented in a chemotactic gradient prior to lectin addition revealed the innate unbound recognition site array. Unbound Con A recognition sites were clustered at the front of 74.7 +/- 0.8% of cells in a "headlight" pattern, but binding sites for other lectins were distributed randomly around the polarized cell. When bound Con A complexes are swept to the tail of the polarized living PMN, "new" unbound Con A binding sites appear at the front of the cell. Neither cycloheximide nor KCN nor colchicine interferred with new binding site appearance. Cytochalasin B and sodium iodacetate prevented PMN polarization and interfered with appearance of new receptors. This suggests that these fresh sites are uncovered, previously cryptic binding sites rather than newly synthesized structures. Lectin binding site topography and movement are related to the functional state of the PMN. Since both Con A and certain bacteria bind to mannose derivatives, we postulate that the "headlight pattern" and uncovering of fresh binding sites aid the PMN in engulfing organisms as the phagocyte moves forward.     

B lymphocyte specificity of lectins of Cepaea nemoralis and Dolichos biflorus: paradoxical binding of anti-A active lectins to human lymphocyte subclasses.

Binding of four blood group A-specific lectins, from Helix pomatia (HP), lucorum (HL), Cepaea nemoralis (CN) and Dolichos biflorus (DB) to human lymphocytes was determined. Use was made of lectins attached to latex particles, as convenient probes to detect binding of lectins to individual cells, Specificity of lectin-latex probes was demonstrated by comparison with agglutination and fluorescent lectin binding; experiments with untreated and enzyme-treated human and animal erythrocytes confirmed the specificity of the lectin-latex beads as did inhibition in the presence of N-acetyl-galactosamine, the immunodominant sugar of blood group A substance. The binding of HP to T cells and a proportion of B, and non-B, non-T cells is confirmed. Binding to B cells in chronic lymphocytic leukaemia (CLL) is also confirmed. HP-latex had the same specificity as soluble HP, but binding did not require pretreatment of lymphocytes with neuraminidase. HL-latex had the same specificity for erythrocytes, normal lymphocyte subpopulations and CLL lymphocytes as HP, but the binding was weaker and required pretreatment of the lymphocytes with neuraminidase to demonstrate it. Contrary to expectation, CN and DB bound to B lymphocytes and did not bind to T lymphocytes. CN binding was almost completely restricted to B cells, whereas DB bound to part of the non-B, non-T populations as well as to a substantial proportion of B cells. Neither CN nor DB labelled malignant T cells. Both CN and DB bound to B cells in CLL. As with HP, pretreatment of lymphocytes with neuraminidase increased the accessibility of receptors, but was not essential to demonstrate labelling with CN-, and DB-latex preparations. Binding of each lectin to lymphocytes was independent of ABO blood group of donor suggesting that ABO antigens may be expressed poorly, if at all, on lymphocytes. Binding is probably due to additional specificities possessed by these lectins. Protease treatment destroyed CN- and DB-binding sites but not HP receptors suggesting that at least two types of binding site are involved.     

Glycoconjugate unique to migrating primordial germ cells differs with genera

Previous cytochemical studies showing that rat primordial germ cells (PGCs) possess a unique surface glycoconjugate containing terminal α-Nacetylgalactosamine were extended in this study to determine whether a similar distinctive glycoconjugate coats the surface of PGCs in the mouse. The results showed that mouse PGCs fail to react with peroxidase-conjugated lectins specific for localizing glycoconjugate with terminal N-acetylgalactosamine. All available lectin conjugates with affinity for other terminal sugars or internal sugar linkages also failed to stain mouse PGCs except for the conjugates that bind to α-fucose. One fucose-specific lectin conjugate stained only PGCs in the early mouse embryo but stained additional sites in more mature embryos and lost reactivity with PGCs after gestational day 14. Another fucose-specific conjugate stained PGCs until day 15, but with less selectivity, and a third such conjugate bound to several sites, but not to PGCs. The results suggest that the developmental mechanisms mediating cellular interaction, migration, and differentiation may be similar in different genera, but the specific structure of the cell surface glycoconjugate involved in these mechanisms differs.     

Effects of different fixatives on staining patterns of four lectins in cultured microvascular endothelial cells

Fixatives have significant influence on lectin histochemistry of tissue sections; however, their roles in lectin fluorescent staining of cultured cells remain unclear. In this study, using cultured microvascular endothelial cells (MVECs) from rat intestinal mucosa, the effects of seven fixatives on the fluorescent staining patterns of four lectins were investigated. The results indicated that every fixative gave concanavalin A (Con A) and wheat germ agglutinin (WGA) strong positive staining in different patterns. When fixed with Zenker’s, periodate–lysine–paraformaldehyde (PLP), 2·5% glutaraldehyde (GA), and 4% paraformaldehyde (PFA) solution, the cell membranes and cytoplasms stained, and the fluorescence in the cell edges was brighter. Rossman’s solution, 95% ethanol, and acetone fixation caused cytoplasmic staining, while the fluorescence was weak and evanescent when using acetone. Dolichos biflorus agglutinin (DBA) and Ulex europaeus agglutinin I (UEA I) were stained; revealing very faint fluorescence in cytoplasms just when PLP and 2·5% GA solution were used. In conclusion, this study shows that fixatives have significant effects on the fluorescent staining of MVECs. Fixatives containing aldehydes and mercury chloride are better options for cell membrane glycans, and those containing ethanol for cytoplasmic ones. Acetone fixation is not suitable for lectin histochemistry.     

Lectin histochemistry of embryonal carcinoma

Histological tissue sections of human testicular embryonal carcinoma from 13 patients and of a xenograft tumour in nude mice, as well as cell lines of human embryonal carcinoma, were investigated with eight different lectins to characterize the distribution of glycoconjugates in embryonal carcinoma. In all cases the malignant cells showed binding with Con A, WGA and RCA I conjugates, whereas other lectins were bound to some, but never to all, tumour cells in each group, revealing the heterogeneity of the malignant cells. A polarization of cancer cells was shown particularly with WGA and RCA I labelling, which was most intense on the luminal borders of the carcinoma cells, where pseudotubular structures were formed. The sugar staining properties were retained in cell culture and in the xenograft tumour. Regardless of the germ cell origin, embryonal carcinoma cells differed from normal germ cells. The distribution of glycoconjugates was also different from that of testicular carcinoma-in-situ germ cells, which share morphological features and the pattern of glycosylation with seminoma cells. However, the similarities in lectin binding pattern of seminomas and embryonal carcinomas suggest the close relationship between the two types of testicular malignancy, without excluding the possibility that embryonal carcinomas were derived from seminomas. Although lectins seem to be less important for differential diagnostic use in testicular cancer, our findings showed the usefulness of lectin histochemistry for characterization of embryonal carcinoma.     

Lectin histochemistry of goblet cells in metaplastic epithelium of human gallbladder

Goblet cells arising in the intestinal metaplasia of chronically inflamed gallbladder were studied by lectin histochemistry and compared with equivalent cells in the small and large intestine. Overall, metaplastic goblet cells reacted more avidly with the majority of lectins and even expressed receptors for lectins that were unreactive with normal intestinal goblet cells. There was, however, considerable variation in lectin binding from one case to another, as well as among the cells of the same specimen. We thus conclude that metaplastic goblet cells in the gallbladder are different from normal intestinal goblet cells, but do not have a uniform lectin binding profile.     

Pea lectin as a universal cell binding agent for ELISA (screening) tests

A cell binding assay (CBA) was developed in which plant lectins are used as binding agents between microtiter plates and human cells. After binding, the cells were fixed by mild glutaraldehyde treatment. Their antigenic activity was investigated by enzyme-linked immunosorbent assay (ELISA) with several monoclonal antibodies. The binding method resulted in cell layers that remained firmly attached to the plates during the washing and incubation procedures of the ELISA. A comparative phenotype analysis, performed by indirect membrane fluorescence, showed that cells bound by this method, do not lose their antigenic activity. This binding assay can be used as a rapid, large scale screening test for monoclonal antibodies to membrane antigens of malignant and normal cells.     

Bandeiraea simplicifolia lectin I and Vicia villosa agglutinin bind specifically to the vomeronasal axons in the accessory olfactory bulb of the rat.

The binding of 21 lectins to the accessory olfactory bulb (AOB) of the rat was examined by histochemistry. Two lectins [Bandeiraea simplicifolia lectin I (BSL-I) and Vicia villosa agglutinin (VVA)] bound specifically to the vomeronasal (VN) axons in the AOB. Seven lectins (Datura stramonium lectin, Erythrina cristagalli lectin, Lycoperisicon esculentum lectin, Ricinus communis agglutinin I, soybean agglutinin, Solanum tuberosum lectin, and Ulex europaeus agglutinin) bound to both VN axons in AOB and olfactory axons in the main olfactory bulb. BSL-I and VVA are useful as the marker of VN axons. This selective binding of lectins indicates the presence of specific glycoconjugates on the surface of VN axons.     

Lymphocyte cell surface glycoproteins which bind to soybean and peanut lectins.

In cellular immunology, peanut (Arachis hypogaea) lectin has been used to selectively agglutinate immature lymphoid cells and soybean (Glycine max-lectin to agglutinate B lymphocytes. We have used affinity chromatography to study the surface glycoproteins of rat and mouse lymphoid cells which bind to these lectins. Thymocyte and T and B lymphocyte glycoproteins were analysed either without modification (native) or after the removal of sialic acid with neuraminidase (asialo). The only native glycoprotein which was seen to bind to peanut lectin was the 95,000 mol. wt sialoglycoprotein from thymocytes. The equivalent molecules from T lymphocytes bound to peanut lectin only after neuraminidase digestion. Thus the selective agglutination of thymocytes by peanut lectin would seem to be due to a partial lack of sialic acid residues on the O-glycosidically-linked oligosaccharides of the thymocyte sialoglycoprotein. The B lymphocyte form of the leucocyte-common antigen was the only prominent native glycoprotein which was seen to bind to soybean lectin and this probably accounts for the specific binding of this lectin to B cells. The leucocyte-common antigens, in their asialo forms, from thymocytes and B and T lymphocytes differed in their binding to the lectins and this establishes that these glycoproteins which share antigenic determinants differ in their carbohydrate structures.     

Lectin histochemistry of galactose and N-acetyl-galactosamine glycoconjugates in normal gastric mucosa and gastric cancer and the relationship with ABO and secretor status

The histochemical binding of four lectin-peroxidase conjugates to normal human gastric mucosa and gastric carcinoma is described. The lectins were peanut agglutinin (PNA) which is specific for galactose residues and soy bean agglutinin (SBA), Dolichos biflorus agglutinin (DBA) and Helix pomatia agglutinin (HPA) which are specific for N-acetylgalactosamine. Binding of PNA to surface mucous cells or normal gastric mucosa occurred in non-secretors but not secretors and was independent of ABO blood group at all sites. PNA binding was unrelated to the immunohistochemical demonstration of Thomsen-Friedenreich (T) antigen. DBA and HPA bound selectively to surface mucous cells in normal gastric mucosa from group A secretors but binding at other sites was independent of ABO status. SBA binding showed no relationship with blood group or secretor status. In gastric cancers the major finding was the occurrence of extensive masking of lectin binding sites by sialic acid which was not seen in normal mucosa. Sialic acid masking was most marked with PNA and least marked with DBA. There was no correlation between lectin binding patterns and the stage or differentiation of tumours. Results are consistent with in vitro studies demonstrating increased sialation of membrane glycoproteins following malignant transformation. Difficulties in interpreting the histochemical demonstration of lectin binding in terms of specific glycoconjugates are discussed.     

Effect of lectins on hepatic clearance and killing of Candida albicans by the isolated perfused mouse liver.

The isolated perfused mouse liver model was used to study the effects of various lectins on hepatic trapping and killing of Candida albicans. After mouse livers were washed with 20 to 30 ml of perfusion buffer, 10(6) C. albicans CFU were infused into the livers. At the time of recovery, 63% +/- 2% (mean +/- standard error of the mean) of the infused C. albicans CFU were recovered from the liver and 14% +/- 1% were recovered from the effluent for a total recovery of 77% +/- 2%. This indicated that 86% +/- 9% of the original inoculum was trapped by the liver and that 23% +/- 2% was killed within the liver. When included in both preperfusion and postperfusion buffers (0.2 mg of lectin per ml), Ulex europeaus lectin (binding specificity for fucose) decreased hepatic trapping of C. albicans by 37% and eluted trapped C. albicans from the liver only when included in postperfusion buffer. By comparison, treatment of C. albicans with U. europeaus lectin before infusion had no effect on the trapping or killing of yeast cells. When Lens culinaris lectin (binding specificity for mannose) was included in the perfusion buffers, hepatic killing of C. albicans increased by 16% with no significant effect on hepatic killing when yeast cells were treated with L. culinaris lectin before infusion. Forty to 55% of the infused C. albicans were killed when concanavalin A (binding specificities for mannose and glucose), Glycine max (binding specificity for N-acetylgalactosamine), or Arachis hypogea (binding specificity for galactose) lectin was included in the perfusion buffer or when yeast cells were treated with these lectins before their infusion. When C. albicans was treated with concanavalin A at a concentration of less than 0.02 mg/ml, hepatic killing of yeast cells was not significantly increased. The data suggest that a fucose-containing receptor on the surface of either sinusoidal endothelial cells or Kupffer cells is involved in the trapping of C. albicans by the perfused mouse liver. Moreover, lectins with binding specificities for mannose, N-acetylgalactosamine, and galactose increased hepatic killing of C. albicans.     

Differential expression of galactose and N-acetylgalactosamine residues during fetal development and postnatal maturation of rat glomeruli as revealed with lectin conjugates

A battery of fluorochrome- or peroxidase-coupled lectins, reacting with alpha- or beta-galactose (Gal), terminal N-acetylgalactosamine (GalNAc), or Gal-(beta 1-3)-GalNAc residues, was used to study the emergence and distribution of cellular glycoconjugates in developing and adult rat glomeruli. Neuraminidase pretreatment of the specimens was applied to monitor the maturation of the glomerular sialoglycoprotein coat. In the adult glomeruli, the lectin conjugates applied reacted sparsely or not at all, but most of them showed an increased reactivity with podocytes and/or the glomerular basement membrane after neuraminidase treatment. In the embryonic glomeruli, lectins reacting with beta-Gal residues prominently bound to the basement membranes, as revealed in double-staining with laminin antibodies. This reactivity decreased first during late postnatal development. Some terminal Gal-(beta 1-3)-GalNAc residues were noted in the earliest podocytes, but obviously soon became covered by sialylation. Furthermore, the developing podocytes prominently displayed alpha-Gal residues, as marked by Maclura pomifera (MPA) and Jacalin reactivities but not by the GSA-I conjugates. During postnatal maturation these reactivities also decreased. The GalNAc-specific Helix pomatia (HPA) and Helix aspersa (HAA) agglutinins bound to basement membranes of evolving podocytes but later revealed in the podocytes only a Golgi-like cytoplasmic reactivity. These two lectins showed a marked difference in their binding to tubular basement membranes. In lectin blotting experiments of electrophoretically separated polypeptides transferred onto nitrocellulose, the peanut agglutinin (PNA) and MPA conjugates revealed upon neuraminidase treatment a broad Mr 140,000 polypeptide, compatible with podocalyxin, both in isolated developing and adult glomeruli. The MPA conjugate revealed a similar polypeptide in developing glomeruli, even without neuraminidase treatment. Similar experiments with the HPA and HAA conjugates revealed different polypeptides in both adult and developing glomeruli. Obviously, in the rat kidney the maturation of the podocyte sialoglycoprotein coat and the glomerular basement membranes are multiphasic processes that continue even during late postnatal development.     

Distribution of cell surface glycoconjugates during secondary neurulation in the chick embryo

Lectin histochemistry was used to examine the expression of cell surface glycoconjugates during secondary neurulation in chick embryos. Fourteen lectins were applied to serial sections of the caudal region of embryos at the various stages of tail bud development. The lectins Bandeiraea simplicifolia, Dolichos biflorus agglutinin, Phaseolus vulgaris leukoagglutinin, soybean agglutinin, Sophora japonica agglutinin, Ulex europaeus agglutinin and succinylated wheat germ agglutinin (sWGA) showed very light or no binding to the developing medullary cord of the tail bud. With the other lectins, staining occurred throughout the early tail bud and solid medullary cord. During cavitation, however, differential expression of cell surface glycoconjugates by different cell populations was observed. The lectins concanavalin A, Lens culinaris agglutinin, Pisum sativum agglutinin, Phaseolus vulgaris erythroagglutinin, Ricinus communis agglutinin and WGA showed basic similarities in the distribution of lectin binding. Of these, the binding pattern of WGA was the most striking. As the medullary cord cells were separating into central mesenchymal and peripheral epithelial populations, WGA bound preferentially to the epithelial cells and the notochord. The lectin PNA, however, became preferentially bound to the mesenchymal cells. Heavy staining by WGA (specific for N-acetylglucosamine and sialic acid) where sWGA staining (specific for N-acetylglucosamine only) was faint suggested that WGA binding was due to the presence of sialic acid containing glycoconjugates.     

The bovine lymphoid system: binding and stimulation of peripheral blood lymphocytes by lectins.

We tested ability of 11 different lectins to stimulate DNA synthesis in bovine peripheral blood lymphocytes, using a wide range of experimental conditions. Five of the 6 lectins which induced DNA synthesis (concanavalin A, succinyl-concanavalin A, phytohemagglutinin M, pokeweed mitogens and lipopolysaccharide) did so under conditions similar to those optimal for stimulation of murine lymphocytes. The other lectin (peanut agglutinin) stimulated normal bovine lymphocytes whereas it does not stimulate normal mouse, rat, guinea pig or human lymphocytes. The binding of 5 different lectins to bovine peripheral blood lymphocytes was measured by fluorescence microscopy. Four of the lectins bound to various proportions of cells. Double labeling experiments using a rhodamine-labeled goat anti-bovine immunoglobulin reagent and fluorescein-labeled lectins showed that both peanut agglutinin and soybean agglutinin bound to lymphocyte populations which were negative for surface immunoglobulin. The majority of lymphocytes negative for surface immunoglobulin bound peanut agglutinin, indicating that this lectin may bind specifically to bovine 'T' lymphocytes.     

A comparative study for ultrastructural localization of intracellular immunoglobulins using peroxidase conjugates

Various experimental conditions were tried to stain intracellular IgG globulins within popliteal lymph node cells of rats and rabbits by the use of specific antibodies and their Fab fragments labelled with peroxidase following two different procedures.Fixation with 4% formaldehyde/24 hr, 1% formaldehyde and 1% glutaraldehyde/1–1.5 hr and 1–1.5% glutaraldehyde/1–1.5 hr provided satisfactory ultrastructural conservation of the tissues. None of these fixatives appeared to denature IgG globulins, but formation of cross-linkages prevents conjugates from reaching antigenic sites. Weak aldehyde fixation may enhance penetration of conjugates; however, ultrastructural detail is poorly preserved and proteins will leak out from insufficiently fixed tissue, thus increasing the possibility of staining artifacUnder our conditions, best results were obtained by using frozen sections prepared from well-fixed specimens. Apparently, the most important points are tissue fixation and sampling, above all other experimental steps. Conjugates with molar ratios of antibody or Fab fragment to peroxidase being one, seem more effective, although no significant differences were noted between peroxidase conjugates of whole antibody molecules and Fab fragments.     

Use of lectin histochemistry in pancreatic cancer.

Lectin peroxidase histochemical analysis was carried out on pancreatic tissue from patients with pancreatic carcinoma and chronic pancreatitis and from subjects with normal pancreas to find a tumour specific pattern of lectin binding that would aid histological and cytological diagnosis. There were striking differences between the lectin binding characteristics of the different cell types in the normal pancreas. Acinar cells were uniformly positive for binding with wheat germ agglutinin and soy bean agglutinin while islet cells were usually negative for these lectins. Ulex europaeus I lectin however, was found not to be specific for endothelium, showing positivity also for acinar and ductal tissue. Griffonia simplicifolia II lectin was found to be highly specific for ductal epithelium, and because of this was tested in a hamster pancreatic cancer model where it was not specific for ductal epithelium, reflecting differing carbohydrate expression in the hamster pancreas. Pancreatic carcinomas and chronic pancreatitis bound all five lectins without any qualitative distinction from each other or from normal pancreatic tissue, but there was increased intensity of peanut agglutinin binding to secreted mucins in pancreatic carcinoma, which may be of potential use in radiolabelled lectin scanning.