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PubMed1976

Effect of lectins on the levels of cAMP and cGMP in guinea pig lymphocytes: early responses of lymph node cells to mitogenic and non-mitogenic lectins.

Guinea pig lymph node lymphocytes were reacted with two mitogenic lectins (LcL-A or PHA) and two nonmitogenic lectins (AbL or WGA)m and the levels of cAMP and cGMP were determined during 30 min of culture. Various concentrations of LcL-A and PHA caused modest (1.5 to 2-fold) rises in cAMP levels. However, the rise in cAMP did not correlate with the degree of mitogenicity. AbL caused a greater rise in cAMP than the mitogenic lectins whereas WGA had no effect on cAMP levels. None of the four lectins causes an appreciable (i.e., greater than 1.5-fold) change in cGMP levels. There does not seem to be any positive correlation between early changes of cAMP and/or cGMP and mitogenesis.

Animals↗

PubMed1990

Lectin binding in murine tumour lines with different malignant characteristics. Effect of enzyme (pronase, neuraminidase) treatment on lectin labelling.

We used 5 syngeneic murine tumour systems for studying quantitative lectin surface binding of intact viable tumour cells. We also investigated, for 3 of the tumours, whether the lectin binding sites were susceptible to proteolytic enzyme (pronase) or neuraminidase treatment. There were significant differences between two of the tumour lines in the binding of wheat germ agglutinin (WGA), concanavalin A (ConA). peanut agglutinin (PNA), soybean agglutinin (SBA) and Ulex europeus agglutinin (UEA). There were also variations in lectin binding between the other tumor lines, but these differences were not statistically significant. Lectin binding showed no evident relationship to the malignancy or the metastasis-forming capacity of the respective tumour cell line. Proteolytic treatment, which drastically affects intravenously induced experimental metastasis formation by one of the tumours, caused a decreased binding of SBA, ConA and WGA. Neuraminidase treatment increased both PNA and SBA binding in three different cell lines, presumably by removing sialic acid masking D-galactose and N-acetyl-D-galactose-amine groups.

Animals↗

PubMed1980

Simple test for detection of virus neuraminidase and antineuraminidase using lectins (lectin-neuraminidase test system).

The fast and sensitive detection of virus neuraminidase effectiveness (influenza virus A and B or mumps virus) and of antibodies against virus neuraminidase in human serum is described. Lectin mainly obtained from Arachis hypogaea and Helix pomatia is used in the lectin-neuraminidase test (LN-test). The lectins are capable of agglutinating erythrocytes after virus incubation because virus neuraminidase reveals the T-antigen to be situated on erythrocytes. The presence of anti-neuraminidase in human sera can be detected with the aid of lectins after incubation of the virus suspension with human serum as a result of the agglutination having failed to take place. Neuraminidase activities of the influenza virus A and B are detectable up to a virus dilution of 1: 40,000 and anti-neuraminidase could be determined in human serum samples with titres of up to 1: 10,000. All materials required for the LN-test can be arranged in a set.

Animals↗

PubMed2006

Extending missing-self? Functional interactions between lectin-like NKrp1 receptors on NK cells with lectin-like ligands.

The functions of natural killer (NK) cells are clearly regulated by major histocompatibility complex (MHC) class I molecules on their cellular targets. In mice, this is due to the action of MHC-specific inhibitory receptors belonging to the Ly49 family oflectin-like molecules. The Ly49 receptors are encoded in the NK gene complex (NKC) that contains clusters of genes for other lectin-like receptors on NK cells and other hematopoietic cells. Interestingly, recent studies have shown that some of these lectin-like receptors, belonging to the Nkrpl family, can recognize other lectin-like molecules, termed Clr, also encoded in the NKC. These genetically linked loci for receptor-ligand pairs suggest a genetic strategy to preserve this interaction and show several other contrasts with Ly49-MHC interactions. In this review, we discuss these issues and summarize recent developments concerning this non-MHC-dependent regulation of NK cell function.

Animals↗

PubMed2004

Human mannose-binding lectin and L-ficolin function as specific pattern recognition proteins in the lectin activation pathway of complement.

The innate immune response in vertebrates and invertebrates requires the presence of pattern recognition receptors or proteins that recognize microbial cell components including lipopolysaccharide, bacterial peptidoglycan (PGN), and fungal 1,3-beta-D-glucan. We reported previously that PGN and 1,3-beta-D-glucan recognition proteins from insect hemolymph were able to induce the activation of the prophenoloxidase-activating system, one of the major invertebrate innate immune reactions. The goal of this study was to characterize the biochemical properties and effects of the human counterparts of these molecules. Soluble pattern recognition proteins were purified from human serum and identified as human mannose-binding lectin (MBL) and L-ficolin. The use of specific microbial cell component-coupled columns demonstrated that MBL and L-ficolin bind to PGN and 1,3-beta-D-glucan, respectively. Purified MBL and L-ficolin were associated with MBL-associated serine proteases-1 and -2 (MASPs) and small MBL-associated protein as determined by Western blot analysis. Finally, the binding of purified MBL/MASP and L-ficolin/MASP complexes to PGN and 1,3-beta-D-glucan, respectively, resulted in the activation of the lectin-complement pathway. These results indicate that human PGN and 1,3-beta-D-glucan recognition proteins function as complement-activating lectins.

Amino Acid Sequence↗

PubMed1985

T cell triggering by lectins. I. Requirements for interleukin 2 production; lectin concentration determines the accessory cell dependency.

The requirements for lectin-induced interleukin 2 (IL2) production by human T cells have been investigated. With two different types of T cells, the Jurkat T cell lymphoma and highly purified HLA class II- peripheral T cells, the amount of IL2 produced was strongly dependent on the lectin concentration used. Addition of accessory cells caused a shift in the dose-response curve, resulting in strongly enhanced IL2 production at low concentrations. Thus, the (absolute) accessory cell dependency for T cells to produce IL2 is defined by experimental conditions. Only at lectin concentrations that were found to be optimal in the presence of accessory cells, removal of these cells abrogates IL2 production. Furthermore, after depletion of monocytes IL 2 production by peripheral T cells became almost completely dependent on the presence of thiols in the culture medium. In contrast, the IL2 production by the Jurkat line was not influenced by addition of thiols. The Jurkat model was used to study the nature of accessory cell because this cell line does not show any reactivity to allogeneic cells. Various myeloid and B lymphoid cell lines were tested as accessory cells. The capacity to function as accessory cell was not related to the monocytic origin of the cell. B cell lines were far more effective than monocytes, as two HLA class II- monocytic cell lines were not active. Even after HLA class II determinants were induced on these cells by incubation with an interferon-gamma-containing conditioned medium, they failed to act as as accessory cells. These experiments question the importance of HLA class II molecules and monokines, such as IL1, for lectin-induced IL2 production.

Antigen-Presenting Cells↗

PubMed1985

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

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

Animals↗

PubMedDate not supplied

[Effect of exogenous lectin on the endogenous lectin and antioxidant enzymes activity and flavonoid content in wheat].

The presawing treatment of wheat seeds by lectin specific to the plant and its compositions with gapten and nitrogen fixation bacteria on the change in enzyme activity of antioxidant system of plant protection (peroxydase and katalase), endogenous lectin activity and flavonoid content in wheat leaves was studied in vegetation experiments. It is shown, that different biochemical links of protection plant system are activated, i.e. lectin activity in leaves increases 1.3 to 1.5 times, peroxydase activity and katalase activity rises 1.5 times and 5.0 to 8.0 times respectively and flavonoide content in leaves of vegetating plants increases under normal conditions of plant growth at the influence of factors of lectin nature.

Antioxidants↗

PubMed1988

Localization of fucosyl moieties in the mouse renal cortex by lectin histochemistry using the fucose binding lectins LTA and UEA I and by autoradiography using 3H-labelled fucose.

The binding patterns of the two fucose binding lectins, Lotus tetragonolobus (LTA) and Ulex europeus I (UEA I) were investigated using fluorescence lectin histochemistry on the unfixed renal cortex of the mouse (NMRI) embedded in LR-Gold. The fluorescence staining results were compared with the autoradiographic localization of the incorporation of radioactive fucose into the renal cortex. For this study the turnover of incorporated 3H-fucose in the renal cortex was investigated 30 min, 2 h and 8 h after application. The localization of the radioactive fucose within the renal cortex corresponded well to the labelling pattern observed for lecting histochemistry using LTA. In contrast, with UEA I, no binding sites for this lectin could be observed. The results of our investigation clearly showed that fucosyl moieties in the renal cortex of the NMRI mouse are recognized by the fucose binding lecting LTA, but not by UEA I and that postembedding fluorescence histochemistry with LTA on the LR-Gold embedded kidney is a suitable technique for the localization of fucosyl moieties at the light microscopical level.

Animals↗

PubMed1990

Complex carbohydrate-lectin interaction at the interface: a model for cellular adhesion. I. Effect of vesicle size on the kinetics of aggregation between a fatty acid conjugate of lectin and a liposomal asialoganglioside.

Two types of phospholipid vesicles capable of mutual recognition have been tailor-made to serve as a model system for the study of carbohydrate-mediated cellular adhesion. One of the vesicles contained a fatty acid conjugate of a galactose specific lectin (lectin vesicle) and the other an asialoganglioside with a reactive terminal galactose residue (galactose vesicle). The kinetics of aggregation of these two types of vesicles was followed by monitoring time-dependent change in turbidity. A 10-100-fold enhancement in the forward rate constant (kf ranging from 7.1 x 10(5) to 4.5 x 10(7) M-1.s-1 at 27 degrees C) was observed when compared with that for the lectin-galactose system in solution (kf being 4.5 x 10(5) M-1.s-1), reported in the literature. A study of the influence of vesicle size on the rate of aggregation showed that enhancement depended on the curvature of the galactose vesicle rather than the density of asialoganglioside suggesting a possible diffusion in the plane of the membrane. The ratio, kf/kd is found to be approx. 10(10) M-1 indicating that the formation of multiple bonds plays a role for stable adhesion.

Cell Adhesion↗

PubMed1996

Failure of glucose-binding lectins Con A and Lentil Lectin to identify glycation of haemoglobin.

We have studied the interaction of Concanavalin A and Lentil Lectin with glycohaemoglobin by a nephelometric lectin-glycogen/dextran precipitation system and monitored the inhibitory effect of glycohaemoglobin on the precipitation. Although inhibitory effects were clearly demonstrated using simple sugars and transferrin, no effect was observed by glycohaemoglobin in relevant concentrations. This is compared to affinity chromatography, binding studies using gel filtration and electrophoresis, and affinity studies using Concanavalin A immobilised on magnetisable polymer particles. Lack of interaction between glycohaemoglobin and lectins is discussed in view of steric constraints and reduced availability of the glycated residues and the stereochemical form of the glycated 1-amino-1-deoxy-fructosyl residues in glycohaemoglobin.

Binding Sites↗

PubMed1984

The lectin reactivity and lectin-like activity of allergenic pollen extracts.

The binding of soluble components of pollen grains to plant-stigma receptors can be inhibited by concanavalin A. This lectin-like activity of pollen components is important in the genetic control of plant reproduction. Aqueous extracts of allergenic pollens also react with concanavalin A. Agarose gel-diffusion precipitates were used to survey and characterize the ability of allergenic pollen extracts to react with concanavalin A and other lectins. Concanavalin A alone precipitated with extracts of plantain, American beech, white ash, and corn pollens. Surprisingly, extracts of the pollen from certain plants also precipitated when the extracts were diffused against pollen extracts from other plants. Pollen extracts of alfalfa, white ash, American beech, burweed marsh elder, redtop grass, corn, plantain, orchard grass, and aspen reacted with one or more other pollen extracts. Extract precipitin activity was reliably obtained after extracting pollens for 20 min with pH 7.5, 0.05M Tris buffer in 0.2M of saline. Optimal agarose gel conditions for detecting the precipitin reactions were pH 8.5 to 9.0, 75 mM borate buffer made to an ionic strength of 1.5M with NaCl for concanavalin A pollen reactions and 0.015M with NaCl for pollen-pollen reactions. The presence of the borate ion was necessary for optimal detection of the agarose gel precipitates. Studies of the inhibition of the lectin-pollen and pollen-pollen reactions with specific mono and disaccharides revealed many similarities and differences between the two types of reactions. The high concentrations of glycerol used to stabilize pollen extracts also inhibit these reactions.

Concanavalin A↗

PubMed1978

Studies on lectins. XXXIX. S-Glycosyl polyacrylamide gels for affinity chromatography of lectins.

Hydrophilic water-insoluble gels suitable for affinity chromatography of lectins have been prepared by copolymerization of acrylamide, N,N'-methylene bisacrylamide and alkenyl 1-thioglycosides. Water-soluble copolymers of analogous type have been obtained by omitting the cross-linking agent, N,N'-methylene bisacrylamide. In affinity chromatography of the Ricinus communis lectin it could be shown that the capacity for the lectin of the water insoluble copolymers was more than four times higher in copolymers having the S-beta-D-galactosyl ligand attached through a methylene bridge than in derivatives with a nonamethylene spacer. None of the insoluble S-beta-D-glycosyl copolymers prepared could be shown usable as affinity adsorbent for glycosidases though the corresponding soluble copolymers inhibited the activity of the enzymes.

Acrylamides↗

PubMed1987

Affinophoresis of pea lectin and fava bean lectin with an anionic affinophore, bearing rho-aminophenyl-alpha-D-mannoside as an affinity ligand.

Affinophoresis is an electrophoretic separation technique for biological polymers with the aid of an affinophore, which is a macromolecular polyelectrolyte bearing affinity ligands. The affinophore migrates rapidly in an electric field, and consequently the electrophoretic mobility of molecules having an affinity for the ligand is specifically changed. An anionic affinophore-bearing mannosyl residue was synthesized for the affinophoresis of lectins. rho-Aminophenyl-alpha-D-mannopyranoside and aminomethanesulphonic acid were coupled to about one-tenth and one-fifth, respectively, of the carboxyl groups of succinyl-poly-L-lysine with an average degree of polymerization of 120 by the use of a water-soluble carbodiimide. Extracts of seeds of pea (Pisum sativum) or fava bean (Vicia fava) were subjected to two-dimensional agarose gel electrophoresis, in which the first dimension was ordinary agarose gel electrophoresis and the second dimension was affinophoresis with the affinophore. The separated proteins were stained with Coomassie Blue R250. The lectins in both seed extracts were separated from a diagonal line formed by other proteins in the extracts. About 10 ng of the separated pea lectin was detected on a nitrocellulose blot by immunostaining with a horseradish peroxidase-conjugated second antibody.

Aniline Compounds↗

PubMed1996

Knowledge-based modeling of a legume lectin and docking of the carbohydrate ligand: the Ulex europaeus lectin I and its interaction with fucose.

Ulex europaeus isolectin I is specific for fucose-containing oligosaccharide such as H type 2 trisaccharide alpha-L-Fuc (1-->2) beta-D-Gal (1-->4) beta-D-GlcNAc. Several legume lectins have been crystallized and modeled, but no structural data are available concerning such fucose-binding lectin. The three-dimensional structure of Ulex europaeus isolectin I has been constructed using seven legume lectins for which high-resolution crystal structures were available. Some conserved water molecules, as well as the structural cations, were taken into account for building the model. In the predicted binding site, the most probable locations of the secondary hydroxyl groups were determined using the GRID method. Several possible orientations could be determined for a fucose residue. All of the four possible conformations compatible with energy calculations display several hydrogen bonds with Asp-87 and Ser-132 and a stacking interaction with Tyr-220 and Phe-136. In two orientations, the O-3 and O-4 hydroxyl groups of fucose are the most buried ones, whereas two other, the O-2 and O-3 hydroxyl groups are at the bottom of the site. Possible docking modes are also studied by analysis of the hydrophobic and hydrophilic surfaces for both the ligand and the protein. The SCORE method allows for a quantitative evaluation of the complementarity of these surfaces, on the basis of molecular lipophilicity calculations. The predictions presented here are compared with known biochemical data.

Artificial Intelligence↗

PubMed1999

Helianthus tuberosus lectin reveals a widespread scaffold for mannose-binding lectins.

BACKGROUND: Heltuba, a tuber lectin from the Jerusalem artichoke Helianthus tuberosus, belongs to the mannose-binding subgroup of the family of jacalin-related plant lectins. Heltuba is highly specific for the disaccharides Man alpha 1-3Man or Man alpha 1-2Man, two carbohydrates that are particularly abundant in the glycoconjugates exposed on the surface of viruses, bacteria and fungi, and on the epithelial cells along the gastrointestinal tract of lower animals. Heltuba is therefore a good candidate as a defense protein against plant pathogens or predators. RESULTS: The 2.0 A resolution structure of Heltuba exhibits a threefold symmetric beta-prism fold made up of three four-stranded beta sheets. The crystal structures of Heltuba in complex with Man alpha 1-3Man and Man alpha 1-2Man, solved at 2.35 A and 2.45 A resolution respectively, reveal the carbohydrate-binding site and the residues required for the specificity towards alpha 1-3 or alpha 1-2 mannose linkages. In addition, the crystal packing reveals a remarkable, donut-shaped, octahedral assembly of subunits with the mannose moieties at the periphery, suggesting possible cross-linking interactions with branched oligomannosides. CONCLUSIONS: The structure of Heltuba, which is the prototype for an extended family of mannose-binding agglutinins, shares the carbohydrate-binding site and beta-prism topology of its galactose-binding counterparts jacalin and Maclura pomifera lectin. However, the beta-prism elements recruited to form the octameric interface of Heltuba, and the strategy used to forge the mannose-binding site, are unique and markedly dissimilar to those described for jacalin. The present structure highlights a hitherto unrecognized adaptability of the beta-prism building block in the evolution of plant proteins.

Agglutinins↗

PubMed1982

Lectins as inducers of interferon-gamma production in human lymphocytes: lentil lectin is highly efficient.

Several of many tested plant lectins induced interferon (IFN) production in cultures of human peripheral blood mononuclear leucocytes (PBL). The mannose-binding lectin obtained from Lens culinaris (LCL) was a particularly efficient inducer of trypsin-sensitive antiviral activity, which qualified as IFN-gamma because it was 90-95% destroyed by pH 2 treatment but not neutralized by anti-IFN-gamma antibodies. However, such antibodies neutralized the residual 5-10% pH 2-resistant IFN, which therefore represented IFN-alpha. Further evidence for the IFN-gamma nature of the LCL-induced IFN was that its production in PBL cultures required both T lymphocytes and macrophages and that its induction of antiviral resistance in human amnion cells was significantly delayed compared with IFN-alpha. Under optimal conditions LCL induced titres of IFN-gamma corresponding to more than 20,000 IFN-alpha units/ml medium, higher than observed with other tested, established IFN-gamma inducers. Other desirable properties of this lectin, as discussed, also suggest that it will be of value for efficient large-scale IFN-gamma production.

Humans↗

PubMed1990

Comparison of Dolichos biflorus lectin and other lectin-horseradish peroxidase conjugates in staining of cutaneous blood vessels in the hairless mini-pig.

Angiogenesis is necessary for normal growth, wound healing, and plays a key role in many pathologic processes. A variety of endothelial markers have been used to investigate angiogenesis. Unfortunately, excellent markers for vascular endothelium in human tissues exhibit little or no staining of endothelia in tissues of other animal species, including the pig. We are interested in the hairless Yucatan strain of mini-pig as an animal model for studying cutaneous wound healing because its skin is histologically and functionally very similar to that of man. Hoping to find a specific marker to identify vascular endothelium in the mini-pig, we therefore screened a battery of 11 different lectin-horseradish peroxidase conjugates. Based on specificity and staining intensity, Dolichos biflorus agglutinin (DBA) was chosen from this battery to investigate vascular changes in the healing of cutaneous wounds in the mini-pig. When compared with routine histologic sections stained with hematoxylin and eosin, blood vessels were much easier to identify in sections stained histochemically with DBA. Lectin histochemistry was particularly useful in investigations of early events in angiogenesis during wound healing when newly derived capillary buds and minute blood vessels were obscured in normal histologic sections by an inflammatory cell infiltrate associated with the healing wound. Ultrastructural lectin cytochemistry revealed staining along the luminal surface and the basolateral plasmalemma of endothelial cells. Histochemical staining with DBA promises to provide a useful method for further investigation of angiogenesis and other vascular phenomena in a variety of normal and pathologic processes using the hairless Yucatan strain of mini-pig as the animal model.

Animals↗