Difference in the ability of blood group-specific lectins and monoclonal antibodies to recognize the ABH antigens in human tissues

Rosetting revisited: a critical look at the evidence for host erythrocyte receptors in Plasmodium falciparum rosetting

Malaria remains a major cause of mortality in African children, with no adjunctive treatments currently available to ameliorate the severe clinical forms of the disease. Rosetting, the adhesion of infected erythrocytes (IEs) to uninfected erythrocytes, is a parasite phenotype strongly associated with severe malaria, and hence is a potential therapeutic target. However, the molecular mechanisms of rosetting are complex and involve multiple distinct receptor–ligand interactions, with some similarities to the diverse pathways involved in P. falciparum erythrocyte invasion. This review summarizes the current understanding of the molecular interactions that lead to rosette formation, with a particular focus on host uninfected erythrocyte receptors including the A and B blood group trisaccharides, complement receptor one, heparan sulphate, glycophorin A and glycophorin C. There is strong evidence supporting blood group A trisaccharides as rosetting receptors, but evidence for other molecules is incomplete and requires further study. It is likely that additional host erythrocyte rosetting receptors remain to be discovered. A rosette-disrupting low anti-coagulant heparin derivative is being investigated as an adjunctive therapy for severe malaria, and further research into the receptor–ligand interactions underlying rosetting may reveal additional therapeutic approaches to reduce the unacceptably high mortality rate of severe malaria.

Molecular deciphering of the ABO system as a basis for novel diagnostics and therapeutics in ABO incompatible transplantation

In recent years ABO incompatible kidney transplantation (KTx) has become a more or less clinical routine procedure with graft and patient survival similar to those of ABO compatible transplants. Antigen-specific immunoadsorption (IA) for anti-A and anti-B antibody removal constitutes in many centers an important part of the treatment protocol. ABO antibody titration by hemagglutination is guiding the treatment; both if the recipient can be transplanted as well as in cases of suspected rejections if antibody removal should be performed. Despite the overall success of ABO incompatible KTx, there is still room for improvements and an extension of the technology to include other solid organs. Based on an increased understanding of the structural complexity and tissue distribution of ABH antigens and the fine epitope specificity of the ABO antibody repertoire, improved IA matrices and ABO antibody diagnostics should be developed. Furthermore, understanding the molecular mechanisms behind accommodation of ABO incompatible renal allografts could make it possible to induce long-term allograft acceptance also in human leukocyte antigen (HLA) sensitized recipients and, perhaps, also make clinical xenotransplantation possible.

Differential glycosylation of MUC1 and CEACAM5 between normal mucosa and tumour tissue of colon cancer patients

Altered glycosylation in epithelial cancers may play an important role in tumour progression, as it may affect tumour cell migration and antigen presentation by antigen presenting cells. We specifically characterise the glycosylation patterns of two tumour antigens that are highly expressed in cancer tissue and often detected in their secreted form in serum: the epithelial mucin MUC1 and carcinoembryonic antigen (CEA, also called CEACAM5). We analysed 48 colorectal cancer patients, comparing normal colon and tumour epithelium within each patient. Lectin binding was studied by a standardised CEA/MUC1 capture ELISA, using several plant lectins, and the human C-type lectins MGL and DC-SIGN, and Galectin-3. Peanut agglutinin (PNA) bound to MUC1 from tumour tissue in particular, suggests increased expression of the Thomsen-Friedenreich antigen (TF-antigen) (Core 1, Galβ1-3GalNAc-Ser/Thr). Only small amounts of Tn-antigen (GalNAcα-Ser/Thr) expression was observed, but the human C-type lectin MGL showed increased binding to tumour-associated MUC1. Furthermore, sialylation was greatly enhanced. In sharp contrast, tumour-associated CEA (CEACAM5) contained high levels of the blood-group related carbohydrates, Lewis X and Lewis Y. This correlated strongly with the interaction of the human C-type lectin DC-SIGN to tumour-associated CEA, suggesting that CEA can be recognized and taken up by antigen presenting cells. In addition, increased mannose expression was observed and branched N-glycans were prominent, and this correlated well with human Galectin-3 binding. These data demonstrate that individual tumour antigens contain distinct glycan structures associated with cancer and, since glycans affect cellular interactions with its microenvironment, this may have consequences for progression of the disease.

Utilization of lectin-histochemistry in forensic neuropathology: lectin staining provides useful information for postmortem diagnosis in forensic neuropathology

We have investigated the deposition of glycoconjugates in human brain tissue with or without brain disorders. In this review we describe the application of lectin-histochemistry techniques to forensic neuropathology. Lectin staining is able to reveal several kinds of carbohydrate-related depositions in addition to the conventional degenerative changes including senile plaques, neurofibrillary tangles and corpora amylacea. The senile plaques and neurofibrillary tangles were clearly stained by Con A, PSA and GSI lectins, the corpora amylacea which is relevant to repeated brain hypoxia and mitochondrial damage was also easily detected by these and many other kinds of lectins. Amorphous spaces were detected around blood vessels and independently from blood vessels by lectin staining in the white matter from patients with brain disorders or severe edema. The white matter lesions were not considered relevant for forensic pathology, until a large group of cerebral white matter lesions were detected in the elderly with increasing frequency by modern neuro-imaging methods. The spherical deposits were newly detected by lectin staining in the molecular layer of the dentate gyrus of the hippocampal formation chiefly from patients with schizophrenia or cognitive dysfunctions.

Structure and ligand binding of carbohydrate-binding module CsCBM6-3 reveals similarities with fucose-specific lectins and "galactose-binding" domains

Carbohydrate-binding polypeptides, including carbohydrate-binding modules (CBMs) from polysaccharidases, and lectins, are widespread in nature. Whilst CBMs are classically considered distinct from lectins, in that they are found appended to polysaccharide-degrading enzymes, this distinction is blurring. The crystal structure of CsCBM6-3, a "sequence-family 6" CBM in a xylanase from Clostridium stercorarium, at 2.3 A reveals a similar, all beta-sheet fold to that from MvX56, a module found in a family 33 glycoside hydrolase sialidase from Micromonospora viridifaciens, and the lectin AAA from Anguilla anguilla. Sequence analysis leads to the classification of MvX56 and AAA into a family distinct from that containing CsCBM6-3. Whilst these polypeptides are similar in structure they have quite different carbohydrate-binding specificities. AAA is known to bind fucose; CsCBM6-3 binds cellulose, xylan and other beta-glucans. Here we demonstrate that MvX56 binds galactose, lactose and sialic acid. Crystal structures of CsCBM6-3 in complex with xylotriose, cellobiose, and laminaribiose, 2.0 A, 1.35 A, and 1.0 A resolution, respectively, reveal that the binding site of CsCBM6-3 resides on the same polypeptide face as for MvX56 and AAA. Subtle differences in the ligand-binding surface give rise to the different specificities and biological activities, further blurring the distinction between classical lectins and CBMs.

The carbohydrate deposits detected by histochemical methods in the molecular layer of the dentate gyrus in the hippocampal formation of patients with schizophrenia, Down's syndrome and dementia, and aged person

Post-mortem brain tissue was obtained from 28 patients with brain disorders, of which 15 had clinically diagnosed schizophrenia, 6 Alzheimer type dementia, 5 dementia with tangles and 2 cases of Down's syndrome. The controls were 22 cases from autopsies without brain disorders or with no known episodes of brain disorder. The tissues were stained for the detection of carbohydrate deposits in the hippocampal formation, using lectin, immunohistochemical and conventional staining methods. The staining revealed the existence of spherical deposits in the inner and middle molecular layers of the dentate gyrus in the hippocampal formation which contained fucose, galactose, N-acetyl galactosamine, N-acetyl glucosamine, sialic acid, mannose and chondroitin sulfate. The number of the deposits was higher in patients with brain disorder such as schizophrenia, Alzheimer type dementia, dementia with tangles or Down's syndrome, and in some aged individuals, in comparison to those in younger individuals. No deposits were detected in a few younger or aged individuals. Spherical deposits 3-10 microm in diameter may be an immature form of the corpora amylacea, since they were similar in the histochemical characteristics with lectin, immunohistochemical and conventional staining methods. However, differing staining ability by hematoxylin, periodic acid Schiff's reagent and antibodies against the intracellular degraded proteins such as ubiquitin and tau-protein was observed. The antibodies against ubiquitin and tau-protein showed clear reactivity with the corpora amylacea and no reactivity with spherical deposits, indicating that the corpora amylacea has an intracellular origin and spherical deposits an extracellular matrix origin. The results obtained in this study indicate that not only neuronal degeneration but also unusual glycometabolism in neurons may disturb the neuronal function and cause brain disorders, and that spherical deposits may cause dysfunction of the neuronal network in the dentate gyrus of the hippocampus which is closely linked with recognition and memory functions.

Distribution of H type 1 and of H type 2 antigens of ABO blood group in different cells of human submandibular gland

We have examined the immunohistochemical distribution of H Type 1 and of H Type 2 substances of the ABO blood group system in human submandibular gland using either of the two anti-H monoclonal antibodies MAb 1E3 and MAb 3A5. MAb 3A5 was specific for H Type 2, and MAb 1E3 reacted with each of H Type 1-H Type 4 artificial antigens. We have developed a competitive inhibition method against H Type 2 and have obtained MAb 1E3, which is fairly specific for H Type 1 under certain conditions. Mucous cells from secretors were strongly stained by 1E3 and weakly by 3A5, whereas those from nonsecretors showed no reaction with 1E3 and 3A5. Serous cells from both secretors and nonsecretors were stained neither by 1E3 nor by 3A5. Striated and interlobular duct cells were strongly stained by 1E3 and by 3A5, regardless of the secretor status. These results indicated that the expressions of the H Type 1 and H Type 2 in different cell types of the submandibular gland were controlled by different genes. In addition, we have determined the acceptor specificity of two alpha(1,2)fucosyltransferases (H and Se enzymes) after transient expressions of the FUT1 and FUT2 in COS7 cells, and found that the H enzyme activity was similar for both Type 1 and Type 2 precursors, and that Se enzyme activity with the Type 1 precursor was higher than that with the Type 2 precursor. Expression of the H Type 1 antigen in mucous cells was found to be dependent on the Se gene, whereas expressions of the H Type 1 and H Type 2 antigens in striated and interlobular duct cells were dependent on the H gene. (J Histochem Cytochem 46:69-76, 1998)

Expression of human H-type alpha1,2-fucosyltransferase encoding for blood group H(O) antigen in Chinese hamster ovary cells. Evidence for preferential fucosylation and truncation of polylactosamine sequences

The human H(O) blood group is specified by the structure Fucalpha1-2Galbeta1-R, but the factors regulating expression of this determinant on cell surface glycoconjugates are not well understood. To learn more about the regulation of H blood group expression, cDNA encoding the human H-type GDPFuc:beta-D-galactoside alpha1, 2-fucosyltransferase (alpha1,2FT) was stably transfected into Chinese hamster ovary (CHO) cells. The new cell line, designated CHO(alpha1,2)FT, expressed surface neoglycans containing the H antigen. The structures of the fucosylated neoglycans in CHO(alpha1, 2)FT cells and the distribution of these glycans on glycoproteins were characterized. Seventeen percent of the [3H]Gal-labeled glycopeptides from CHO(alpha1,2)FT cells bound to the immobilized H blood group-specific lectin Ulex europaeus agglutinin-I (UEA-I), whereas none from parental CHO cells bound to the lectin. The glycopeptides from CHO(alpha1,2)FT cells binding to UEA-I contained polylactosamine [3Galbeta1-4GlcNAcbeta1-]n with the terminal sequence Fucalpha1-2Galbeta1- 4GlcNAc-R. Fucosylation of the polylactosamine sequences on complex-type N-glycans in CHO(alpha1, 2)FT cells caused a decrease in both sialylation and length of polylactosamine. Unexpectedly, only small amounts of terminal fucosylation was found in diantennary complex-type N-glycans. The O-glycans and glycolipids were not fucosylated by the H-type alpha1, 2FT. Two major high molecular weight glycoproteins, one of which was shown to be the lysosome-associated membrane glycoprotein LAMP-1, preferentially contained the H-type structure and were bound by immobilized UEA-I. These results demonstrate that in CHO cells the expressed H-type alpha1,2FT does not indiscriminately fucosylate terminal galactosyl residues in complex-type N-glycans, but it favors glycans containing polylactosamine and dramatically alters their length and sialylation.

Ethnic differences in the expression of blood group antigens in the salivary gland secretory cells from German and Japanese non-secretor individuals

Type 1 ABO blood group antigens (peripheral core structure: Gal beta 1-3GlcNAc beta 1-R) are expressed mainly in endodermally-derived tissues, but are not synthesized in mesodermally-derived tissues. In the former tissues, H type 1 antigen is generated largely by alpha-2-L-fucosyltransferase encoded by secretor (Se) gene and acting on the terminal galactose of the type 1 precursor chain. This theory has been generally accepted, and it seems that the expression of ABO blood group antigens is absent, or expressed at a low level, in these tissues from non-secretor individuals. In this immunohistochemical study on the secretory cells of salivary glands, we found ethnic difference between German and Japanese non-secretor individuals in the expression of blood group antigens: i.e. the expression of the type 1 blood group antigens is present in these cells from Japanese non-secretor individuals but absent from German. A possible explanation is that another alpha-2-L-fucosyltransferase, independent of the secretor gene, is present in Japanese non-secretor individuals.

Heterogeneous histochemical reaction pattern of the lectin Bandeiraea (Griffonia) simplicifolia with blood vessels of human full-term placenta

Bandeiraea simplicifolia lectin (BS-I) stains vascular endothelium in various species. In humans, less than 10% of the specimens studied exhibit a reaction with BS-I. In the present histochemical study, the reactivity of BS-I with placental blood vessels and its correlation with the blood group from mother and newborn child was investigated. Acetone-fixed cryosections of representative tissue segments of human full-term placenta and umbilical cord were stained with BS-I. The staining pattern of tissues from patients with different blood groups was identical, although the reaction of BS-I in the placenta was heterogeneous. BS-I did not react with the umbilical cord. Vascular smooth muscle cells at the insertion site of the umbilical cord into the chorionic plate, and endothelium deeper in the chorionic plate, became progressively stained. The endothelial cells and tunica muscularis of smaller arteries and veins in stem villi lost their reactivity in parallel with decreasing vessel size. Arterioles and venules reacted heterogeneously. Capillaries, trophoblastic basement membranes, especially epithelial plates, and sometimes the syncytiotrophoblast were labelled in several terminal villi. The data indicate that 1) the placenta binds BS-I to fetal endothelium independent of the blood group, 2) cell-surface antigens on placental endothelial cells are expressed heterogeneously and 3) cell-surface glycans are constituted in an organ-specific manner on human endothelial cells.

Histochemistry with Helix pomatia agglutinin in human germ cell tumors: detection of nongerminomatous components and correlation between HPA reactivity and radiosensitivity in germinomas

Binding sites of Helix pomatia agglutinin (HPA) were examined in 32 patients with intracranial human germ cell tumors. HPA reactivity was found in vascular endothelial cells and erythrocytes of patients with blood type A or AB. HPA-positive neoplastic cells were seen in one yolk sac carcinoma in a patient with blood group A, and in embryonal carcinomas and teratomas irrespective of blood group type. Although in 10 out of 18 germinomas neoplastic cells were totally negative for HPA, another 8 germinomas showed HPA-positive neoplastic cells which were distributed sporadically or in an area and independent of blood group types. HPA-negative germinoma patients showed a very good response to radiotherapy, whereas 4 out of 8 HPA-positive tumors showed poor radiosensitivity, with a residual lesion seen on computed tomography even after the total radiation dose of 40-50 Gy. These findings suggest that HPA-positive neoplastic cells in germinomas indicate components of differentiation of non-germinomatous germ cells. HPA-positive germinomas might be less radiosensitive than HPA-negative germinomas.

Identification of capillaries in sections from skeletal muscle by use of lectins and monoclonal antibodies reacting with histo-blood group ABH antigens

This study was performed to evaluate the application of different lectins and monoclonal antibodies against ABH antigens to detect and characterize carbohydrate structures in capillaries of skeletal muscle from humans and laboratory animals. Blood group specific lectins (Griffonia simplicifolia, Griffonia simplicifolia isolectin B4, Lotus tetragonolobus, Ulex europaeus, and Dolichos biflorus) and monoclonal antibodies reacting with histo-blood group carbohydrate antigens belonging to type 1 (Le(a)) and type 2 (H, A and Le(y)) chains were used as histological markers for capillaries in sections from skeletal muscle. The material consisted of 20 human masseter muscle biopsies from individuals with known blood types: (eight blood group O, nine blood group A, two blood group B, and one blood group AB) and masseter muscles specimens from different laboratory animals (mouse, rat, rabbit, cat, dog, pig, cow, and macaca monkey). Unfixed sections and an avidin alkaline phosphatase method were used to visualize the specific reaction. Ulex lectin stained capillaries in all human biopsies either strongly or moderately. Strong muscle capillary reaction was observed in biopsies from O, B and AB individuals while capillaries from A individuals were only moderately stained. Griffonia simplicifolia marked capillaries in A, B, and AB individuals and Griffonia simplicifolia isolectin B4 stained capillaries in muscle biopsies from B and AB donors. Dolichos biflorus was a weak marker of muscle capillaries from A individuals. Only capillaries from O individuals were stained with the antibody against H type 2. Capillary reaction was not observed with the other antibodies used. Girffonia simplicifolia was an excellent marker for capillaries in mouse muscle while Griffonia simplicifolia isolectin B4 is recommended for rat muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Histochemical analysis of blood group antigens in human sublingual glands and pancreas. An application of high-performance liquid chromatography to estimate the quantity of galactose liberated from tissue sections by alpha-galactosidase digestion

Using immunostaining with monoclonal antibodies (mAbs) from three different sources as well as anti-B lectin, GSAI-B4 staining and alpha-galactosidase digestion, blood group B antigens were localized and analysed in tissue sections of sublingual glands from blood group B and AB individuals. Quantitative analysis of galactose was simultaneously carried out on the supernatant enzyme solution used for treating tissue sections by high-performance liquid chromatography (HPLC). In addition, galactose liberated from the pancreas tissues of blood group B and AB individuals was also estimated by HPLC analysis in order to compare the content of antigens. mAb-B(H079) and GSAI-B4 reacted uniformly with the mucous cells from blood group B and AB secretors. On the other hand, other mAbs-B(B006 and A582) recognized the antigen in a limited number of cells or was even negative in some cases of blood group AB individuals. Only mAb-B(H079) recognized the B antigens in mucous cells from non-secretors. Digestion with alpha-galactosidase resulted in the consistent appearance of H and Le(b) antigens in the mucous cells of all the secretors examined, although the reduction of staining intensity with anti-B reagents was not so marked. Le(y) antigens also appeared in some cases after the enzyme digestion. In non-secretors, Le(b) and Le(y) antigens, but not H antigens, appeared in some mucous cells following enzyme digestion. HPLC analysis of galactose revealed that alpha-galactosidase can specifically liberate the terminal galactose residues of B antigens, and no marked difference was present in the content of liberated galactose from mucous cells of sublingual glands among the individuals investigated (8.5-11.7 nmoles cm-2). No galactose was detected in samples from the sublingual glands of non-secretors, and only a trace amount of galactose was detected in the samples from pancreas tissues. These results suggest that the observed difference in the reactivity of different reagents with each tissue site can be ascribed to both quantitative and qualitative heterogeneity of B antigens.

Histochemical and cytochemical localization of blood group antigens

The oligosaccharide structures of blood group antigens are not the primary gene products; they are constructed in a stepwise manner by adding particular sugar to precursor oligosaccharides via several glycosyltransferases coded for by different blood group genes (Watkins 1966, 1978, 1980). Consequently, final profiles of antigens expressed in each cell type are influenced by many different factors such as the intrinsic composition of glycosyltransferase species which are defined by the genotype of the individuals, relative activity or amount of these enzymes (repression, derepression or induction of the enzymes), competition between enzymes with overlapping substrate specificity, the organization of the enzymes in membranes, utilizability of precursors and specific substrate sugars, and the activity level of degradating enzymes. Changes in the antigen profiles during maturation, differentiation and malignant transformation are thought to be intimately related to the variability of these factors. Although great importance attaches to histo- and cytochemical information on the distribution and levels of glycosyltransferases and messenger RNA corresponding to the relevant enzyme, detailed and precise localization of the blood group antigens and their variants is the base line for analyzing these complex factors. On the basis of individual genotype and histochemical findings about the antigen distribution and the interrelationship between cells and cellular components producing different antigenic structures (cellular and subcellular mosaicism), we can deduce precursor oligosaccharide levels as well as the status of gene activation and its primary product, glycosyltransferases. Thus, these findings are a prerequisite for further analysis at the molecular genetic level. As emphasized in this article, lectin staining or immunostaining methods with MAbs combined with glycosidase digestion procedures are powerful tools for in situ analysis of carbohydrate structures in histochemical systems. Although in some cases valuable results have been obtained by applying the technique, our knowledge concerning the distribution of complex carbohydrate structures is still far from satisfactory. Along with well defined MAbs and lectins, the key to developing our methods further is successful introduction of glycosidases, in particular, endoglycosidases since these reagents are indispensable for analyzing the inner core structures and glycoconjugate species of the blood group antigens. Application of these techniques at the ultrastructural level is an alluring possibility, even though many difficulties must be overcome. Although their functional roles have not yet been determined, a diverse array of macromolecules is known to be decorated with blood group-related antigens.(ABSTRACT TRUNCATED AT 400 WORDS)