The lectin binding pattern of normal and pathologically altered synovial tissue

Light-microscopical lectin-binding studies were carried out in healthy and pathologically altered synovial tissue (osteoarthrosis, rheumatoid arthritis (RA)). Seven lectins were studied: Con A, DBA, PNA, RCA, SBA, UEA-I, and WGA. Con A and WGA mark all lining cells and the majority of subintimal synovial cells. RCA and SBA stain only a portion of lining cells, regardless of the basic pathology. The lectin PNA reacts only with RA and arthrotic material, and is thus suitable for the diagnosis of inflammatory changes in synovial tissue. UEA-1 is a consistent marker for capillary endothelium and large vessels.     

Lectin histochemistry of human skeletal muscle

Biotinyl derivatives of seven plant lectins-concanavalin A (Con A), peanut agglutinin (PNA), Ricinus communis agglutinin I (RCA I), Ulex europeus agglutinin I (UEA I), soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), and wheat germ agglutinin (WGA)-were bound to cryostat sections of biopsied normal human muscle and visualized with avidin-horseradish peroxidase conjugates. A distinct staining pattern was observed with each lectin. The most general staining was observed with Con A, RCA I, and WGA, which permitted strong visualization of the plasmalemma-basement membrane unit, tubular profiles in the interior of muscle fibers, blood vessels, and connective tissue. PNA gave virtually no intracellular staining, while SBA and UEA I selectively stained blood vessels. DBA was unique in providing good visualization of myonuclei. In each case, lectin staining could be blocked by appropriate sugar inhibitors. Neuraminidase pretreatment of the cryostat sections altered the pattern of staining by all lectins except UEA I and Con A; staining with RCA I became stronger and that with WGA became less intense, while staining with PNA, SBA and DBA became stronger and more generalized, resembling that of RCA I. These effects of neuraminidase pretreatment are in conformity with the known structure of the oligosaccharide chains of membrane glycoproteins and specificities of the lectins involved.     

Distribution and changes of glycoconjugates in rat colonic mucosa during development

Summary A study was made of the modifications of glycoconjugates in rat colonic mucosa during development. Sections of the caecum, and proximal and distal portions of the colon from Sprague Dawley rats at different stages of development (embryos, fetuses, suckling, weaning and adult rats) were examined. The sections were incubated with a battery of eight fluoresceinated lectins: DBA, SBA, WGA, LFA, PNA, GS-I, UEA-I and Con A. Some sections were treated with neuraminidase, and others were submitted to sequential saponification-neuraminidase treatment prior to incubation with the lectin (WGA, PNA or LFA). The intensity of the fluorescence was evaluated and graded from absent (–) to very positive (4+). Gradual and progressive changes were seen in colonic glycoconjugates during development. These changes revealed a unique developmental pattern for each lectin, which was independent for each cellular compartment (goblet cells, luminal surface and supranuclear region). Local and regional differences, observed between the different colonic sections, were already present from early stages of development. Moreover, our study showed that for several glycoconjugates, the differentiation process in colonic mucosa began in the distal region and continued through to the proximal region, the former being the first to reach the adult pattern. In the caecum, some lectins maintained a fetal pattern throughout all the periods of development up to the adult stage.     

Distribution and changes of glycoconjugates in rat colonic mucosa during development. A histochemical study using lectins

A study was made of the modifications of glycoconjugates in rat colonic mucosa during development. Sections of the caecum, and proximal and distal portions of the colon from Sprague Dawley rats at different stages of development (embryos, fetuses, suckling, weaning and adult rats) were examined. The sections were incubated with a battery of eight fluoresceinated lectins: DBA, SBA, WGA, LFA, PNA, GS-I, UEA-I and Con A. Some sections were treated with neuraminidase, and others were submitted to sequential saponification-neuraminidase treatment prior to incubation with the lectin (WGA, PNA or LFA). The intensity of the fluorescence was evaluated and graded from absent (-) to very positive (4+). Gradual and progressive changes were seen in colonic glycoconjugates during development. These changes revealed a unique developmental pattern for each lectin, which was independent for each cellular compartment (goblet cells, luminal surface and supranuclear region). Local and regional differences, observed between the different colonic sections, were already present from early stages of development. Moreover, our study showed that for several glycoconjugates, the differentiation process in colonic mucosa began in the distal region and continued through to the proximal region, the former being the first to reach the adult pattern. In the caecum, some lectins maintained a fetal pattern throughout all the periods of development up to the adult stage.     

Different binding to squamous and columnar epithelium of the uterine cervix as a marker of epithelial differentiation

Biotinylated lectins were used to investigate the expression of carbohydrate residues on columnar and squamous epithelium of the uterine cervix. Con A, WGA, RCA I, PNA, UEA I, DBA and SBA were used. In the native exocervical and in metaplastic squamous epithelium of the transformation zone, one group of lectins (Con A, WGA, RCA I and PNA) stained the cell periphery of all epithelial layers. A second group (UEA I, DBA and SBA) colored the cell periphery of the suprabasal cells. The basal layer was always negative. All lectins labeled the apical border and occasionally the cytoplasm of the endocervical columnar epithelium. Lectin-binding of metaplastic and native squamous epithelium could possibly be used as a marker of epithelial differentiation in normal and abnormal conditions.     

Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. I. Gastric region.

The distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA-I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA-I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA-I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA-I, SBA, and WGA; and for Con A, RCA-I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly identifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA-I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.     

Lectin binding to rat spermatogenic cells: Effects of different fixation methods and proteolytic enzyme treatment

Summary The binding of a panel of eight different fluorescein-conjugated lectins to rat spermatogenic cells was investigated. Particular attention was paid to the effects of different fixation methods and proteolytic enzyme digestion on the staining pattern.Concanavalin A (Con A), wheatgerm agglutinin (WGA), succinylated WGA (s-WGA) and agglutinin from gorse (UEA I) stained the cytoplasm of most germ cells as well as the spermatid acrosome. In contrast, peanut agglutinin (PNA), castor bean agglutinin (RCAI) and soy bean agglutinin (SBA) mainly stained the acrosome. The staining pattern varied depending on the fixation method used. PNA was particularly sensitive to formalin fixation, while SBA, DBA and UEA I showed decreased binding and Con A, WGA, s-WGA and RCA I were insensitive to this type of fixation. Pepsin treatment of the sections before lectin staining caused marked changes in the staining pattern; staining with PNA in formalin-fixed tissue sections was particularly improved but there was also enhanced staining with SBA and horse gram agglutinin (DBA). On the other hand, in Bouin- and particularly in acetone-fixed tissue sections, pepsin treatment decreased the staining with several of the lectins, for example WGA and UEA I.     

Ultrastructural localization of WGA, RCA I, LFA and SBA binding sites in the seven-day-old mouse embryo

In the present investigation we localized binding sites for the lectins WGA (wheat germ agglutinin), RCA I (Ricinus communis agglutinin), LFA (Limax flavus agglutinin) and SBA (soya bean agglutinin) in the 7-day-old mouse embryo at the ultrastructural level. Lectin binding sites were localized on formaldehyde fixed embryos, embedded in LR-Gold, using gold-labelled lectins. Binding sites for WGA and RCA I were observed at the surface of the embryonic ectoderm oriented towards the proamnion cavity and the outer surface of the extraembryonic and the embryonic endoderm. Staining for SBA and LFA binding sites was seen in the basement membrane of the ectoderm. Moreover, binding sites for LFA were observed in the nucleoli of cells of the ectodermal, the mesodermal and the endodermal layer and in free ribosomes located in the cytoplasm of these cells.     

Distribution of lectin receptors sites in the zona pellucida of follicular and ovulated rat oocytes.

Carbohydrates of the zona pellucida (ZP) in mammals are believed to have a role in sperm-egg interaction. We have characterized the biochemical nature and distribution of the carbohydrate residues of rat ZP at the light (LM) and electron microscope (EM) levels, using lectins as probes. Immature female rats were induced to superovulate and cumulus-oocyte complexes were isolated from the oviduct, fixed with glutaraldehyde, and embedded in araldite for LM and LR-Gold for EM histochemistry. For examination of follicular oocytes, rat ovaries were fixed with glutaraldehyde and embedded in paraffin. The araldite or paraffin sections were deresined or deparaffinized, respectively, labeled with biotin-tagged lectins as probes, and avidin-biotin-peroxidase complex as visualant. For EM examination, thin LR-Gold sections were labeled with RCA-I colloidal gold complex (RCA/G) and stained with uranyl acetate. LM analyses indicate that in ovulated oocytes the ZP intensely binds peanut agglutinin (PNA); succinylated wheat germ agglutinin, (S-WGA), Griffonia simplisifolia agglutinin-I (GS-I) and soybean agglutinin (SBA), and to a lesser extent, lectins from Ricinus communis (RCA-I), Concanavaia ensiformis (Con A), Ulex europoeus (UEA-I), and wheat germ agglutinin (WGA). The neighboring cumulus cells are considerably less reactive and exhibit membrane staining only with Con A, WGA, and PNA. EM analysis of RCA/G binding revealed intensive binding to the inner layer region of the ZP and moderate binding to cytoplasmic vesicles of the cumulus cells. The ZP of follicular oocytes exhibits a different lectin binding pattern, expressed in staining strongly with PNA and S-WGA, and in a tendency of the lectin receptors to occur in the outer portion of the ZP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lectin binding to collagen strands in histologic tissue sections

Histologic sections from human skin and uterine ligaments were stained with the following FITC conjugated lectins: Con A, WGA, s-WGA, SBA, DBA, UEA I, PNA, RCA I, BPA, GSA I, GSA II, MPA and LPA. The staining of the connective tissue was similar in the dermis and the uterine ligaments and it was most intense in the extracellular matrix containing collagen strands whereas the fibrocytes remained unstained. The staining was clear with glucose or N-acetylglucosamine binding lectins like Con A, WGA, s-WGA and GSA II, which may be related to the presence of glucose residues in collagenous hydroxylysine. The staining with some of the galactose or N-acetylgalactosamine binding lectins like RCA I, DBA, and BPA was less intense. This may reflect the presence of terminal galactose sugars in the hydroxylysine of collagen. No staining was found with SBA, UEA I, PNA, GSAI, MPA or LPA. The results show that different particularly glucose specific lectins bind to the extracellular matrix and especially to collagenous strands in connective tissue. It is suggested that this might be used in histochemical studies of connective tissue and particularly concerning the changes that may occur in different disease states.     

Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. II. Small intestine.

The binding of seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin, UEA-I; and wheat germ agglutinin, WGA) to the small intestine in metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) method. The staining pattern of the epithelium with all lectins except for UEA-I and Con A changed gradually during metamorphic climax; the main component of the epithelium, absorptive cells, gradually became positive for DBA, PNA, and SBA and the scattered goblet cells for RCA-I and WGA. On the other hand, the change of the staining pattern in the connective tissue occurred only for Con A, RCA-I, and WGA, and this change took place rapidly at the beginning of climax (stage 60). Increased staining for Con A and WGA at stage 60 was observed only in a group of connective tissue cells close to the epithelium and in the basement membrane. As metamorphosis progressed, this localization of the staining intensity became less clear. At the completion of metamorphosis (stage 66), the absorptive cells were stained with all lectins except for UEA-I, whereas the goblet cells stained only with RCA-I and WGA. These results indicate that lectin histochemistry can distinguish between larval and adult cells of both two epithelial types (absorptive and goblet cells). The technique may also identify a group of connective tissue cells, close to the epithelium, that possibly induce the metamorphic epithelial changes.     

Lectin binding to newt epidermis: fluorescent localization and effects on motility

The ability of seven lectins to bind to newt epidermal cells and influence their motility was examined. Of the seven fluoresceinated lectins applied to frozen sections containing intact newt skin and migrating epidermis (wound epithelium), only Con A (concanavalin A), WGA (wheat germ agglutinin), and PNA (peanut agglutinin) produced detectable epidermal fluorescence. Con A and WGA each heavily labeled all layers of intact epidermis, but PNA bound only to the more superficial layers. In contrast to a single population of labeled cells in migrating epidermal sheets after treatment with Con A, there were both labeled and unlabeled cells after exposure to either WGA or PNA. The wound bed was labeled by both Con A and WGA, but not by PNA. DBA (Dolichos bifloris agglutinin), RCA I (Ricinus communis agglutinin), and UEA (Ulex europaeus agglutinin), did not produce significant fluorescence with either migrating or intact epidermis. In general, inhibitory effects on epidermal motility correlated with the binding studies. Thus, Con A, WGA, and PNA, the lectins which clearly bound to the epidermis, all produced a concentration-dependent depression in the rate of epidermal wound closure. RCA was somewhat paradoxical in that it was moderately inhibitory despite showing essentially no binding. The effects of SBA and UEA were equivocal. DBA had no effect. These results indicate that the inhibition of motility produced by Con A that we have described previously is not peculiar to this mannose-binding lectin, but is shared by at least one lectin with an affinity for D-GlcNAc (WGA), and one with an affinity for B-D-Gal(1-3)-D-GalNAc (PNA).(ABSTRACT TRUNCATED AT 250 WORDS)     

Trypanosoma rhodesiense bloodstream trypomastigote and culture procyclic cell surface carbohydrates

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRAT at 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diamino-benzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A greater than PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WAG, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M.(ABSTRACT TRUNCATED AT 250 WORDS)     

Distribution of lectin receptors in postimplantation mouse embryos at 6-8 days gestation

We have examined the pattern of binding of eleven lectins--BSL-II, WGA, LPA, Con A, DBA, SBA, LTA, UEA-I, MPA, PNA, and RCA-I, with specificity for a range of saccharides, to postimplantation mouse embryos from 6 to 8 days of gestation. The lectins were used to stain sections of ethanol-fixed paraffin-embedded and formaldehyde-fixed gelatin-embedded embryonic material. Our observations reveal a complex pattern of lectin binding to both cell surfaces and cytoplasm. Many of the lectins bind particularly to the outer surface of visceral endoderm (e.g., DBA, WGA, SBA, and RCA-I) and to the surface of the proamniotic cavity (e.g., RCA-I, PNA, and WGA). In the newly formed mesenchyme of primitive-streak-stage embryos, galactose and N-Ac-neuraminic acid are present but lectins with specificity for other sugars either did not bind to the cells or bound only in small amounts.     

Eosinophilic globule cells in mouse MFH-like sarcomas: lectin histochemistry.

Lectin binding patterns in ten mouse malignant fibrous histiocytoma (MFH)-like sarcomas containing eosinophilic globule (EG) cells and in granular metrial gland (GMG) cells of mouse placenta were stained with nine lectins (Con A, LCA, WGA, DBA, SBA, e-PHA, PNA, RCA-I and UEA-I) by an avidin-biotin-peroxidase-complex method. EG cells stained strongly with DBA, SBA and PNA which are specific for N-acetyl-D-galactosamine and/or D-galactose. DBA and SBA bound throughout the cytoplasm including the globules; PNA reacted preferentially at the cell surface. There was no evidence that these three lectins were reactive for immature EG cells. WGA, RCA-I and e-PHA also gave a slightly to moderately positive reaction to globules of EG cells. The results indicate that the globules contain abundant O-linked sequences of sugars, but also a few N-linked residues. MFH tumor cells showed a variable degree of binding with Con A, RCA-I, and WGA, but did not react with DBA, SBA and PNA. On the other hand, GMG cells exhibited specific affinities for DBA, SBA and PNA with staining patterns similar to those of EG cells. These findings suggest that EG and GMG cells may be of the same cellular lineage.     

Effects of plant lectins on the adhesive properties of baby hamster kidney cells

We studied the effects of different lectins on the adhesive properties of baby hamster kidney (BHK) cells. The purpose of these studies was to learn more about the cell surface receptors involved in cell adhesion. Three adhesive phenomena were analyzed: 1) the adhesion of BHK cells to lectin-coated substrata; 2) the effects of lectins on the adhesion of cells to substrata coated by plasma fibronectin (pFN); and 3) the effects of lectins on the binding of pFN-coated beads to cells. Initial experiments with fluorescein-conjugated lectins indicated that concanavalin A (Con A), ricinus communis agglutinin I (RCA I), and wheat germ agglutinin (WGA) bound to BHK cells but peanut agglutinin (PNA), soybean agglutinin (SBA), and ulex europaeus agglutinin I (UEA I) dod not bind. All three of the lectins which bound to the cells promoted cell spreading on lectin substrata, and the morphology of the spread cells was similar to that observed with cells spread on pFN substrata. Protease treatment of the cells, however, was found to inhibit cell spreading on pFN substrata or WGA substrata more than on Con A substrata or RCA I substrata. In the experiment of cells with Con A or WGA inhibited cell spreading on pFN substrata, but RCA I treatment had no effect. Finally, treatment of cells with WGA inhibited binding to cells of pFN beads, but neither Con A nor RCA I affected this interaction. These results indicate that the lectins modify cellular adhesion in different ways, probably by interacting with different surface receptors. The possibility that the pFN receptor is a WGA receptor is discussed.     

Lectin histochemical study on the infraorbital gland of the Japanese serow (Capricornis crispus)

Histology and lectin histochemistry were performed in the infraorbital gland of the Japanese serow. The gland is composed of glandular tissues and a pouch filled with the secretion. The tissues consist of an inner layer of sebaceous glands and an outer layer of apocrine glands. The male sebaceous layer is made up of the ordinary type, whereas the female's layer consists of the ordinary and modified types. In the apocrine gland stained with Arachis hypogaea (PNA), nine different patterns of glandular tubules were distinguished on the basis of staining of the cytoplasm, the Golgi area of secretory cells and secretion. Secretory modes of apocrine secretion and exocytosis were included in these stainings. Myoepithelial cells stained constantly with Glycine max (SBA) except when only the Golgi area of secretory cells was positive. The modified sebaceous gland was stained with PNA, SBA, Ricinus communis I (RCA), Triticum vulgaris (WGA), Canavalia ensiformis (Con A) and Ulex europaeus I (UEA), while the ordinary type was positive in PNA, RCA, SBA, WGA and Con A. The secretion in the pouch was stained with PNA, RCA, SBA, Dolichos biflorus (DBA), WGA and Con A. These findings suggest that the modified sebaceous gland contains large amounts of glycoconjugates and the apocrine gland shows a cyclic secretory process of apocrine secretion and exocytosis.     

Glycoproteins of murine zona pellucida from unfertilized eggs and two-cell embryos: comparison of the reactivity to lectins

Glycoproteins of zona pellucida were fractionated by SDS-polyacrylamide gel electrophoresis, and their lectin binding was examined after blotting onto nitrocellulose. The specificity of lectin binding to the major zona glycoproteins was the same for zonae isolated from eggs or from two-cell embryos; RCA, WGA, SBA and DBA reacted with all of the glycoproteins, PNA with ZP-1 and ZP-3, and Con A with ZP-2. However, the reactivity of ZP-3 to SBA and DBA was decreased in zonae from two-cell embryos. In addition, two-cell embryo zona contained a band which had different binding specificity to lectins from the major glycoproteins.     

Histochemical study of glycoconjugates in the epididymis of the hamster (Mesocricetus auratus)

Summary The glycoconjugates of hamster epididymis were investigated with conventional and lectin histochemistry. A zone of the caput epididymis, with particular histochemical characteristics, has been differentiated. β-Elimination in combination with lectins was used to establish the presence and distribution of N- and O-linked glycoconjugates. The epithelium, spermatozoa and the intertubular matrix were rich in glycoconjugates. The Golgi apparatus and stereocilia of the principal cells were intensely positive with HPA, PNA and SBA lectins. β-limination indicated that these cells contained abundant O-linked glycoconjugates. Apical and clear cells presented a common lectin affinity; their reactivities towards WGA and UEA-I were very positive. These cells probably contain abundant N-glycoconjugates. The spermatozoa were stained by periodic acid-Schiff (PAS) and by all the lectins (especially in the acrosome), except by those with an affinity for α-l-fucosyl residues; the most intense reaction was found with HPA, WGA, PNA and SBA. Changes in the sperm lectin binding along the ductus were observed: sperm flagellum abruptly acquired WGA and PNA labelling from the posterior caput, and HPA reactivity was negative only in the zone between the caput and the corpus.     

Trypanosoma rhodesiense Bloodstream Trypomastigote and Culture Procyclic Cell Surface Carbohydrates1, 2, 3

Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRATat 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diaminobenzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A < PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WGA, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M. The expression of lectin binding cell surface saccharides of T. rhodesiense WRATat 1 is related to the parasite stage. Sugars resembling α-D-mannose are on the surface of bloodstream trypomastigotes and culture procyclics; n-acetyl-D-galactosamine and D-galactose residues are on bloodstream forms; and n-acetyl-D-glucosamine-like sugars are on procyclic stages.