Monoclonal antibodies directed to the blood group A associated structure, galactosyl-A: specificity and relation to the Thomsen-Friedenreich antigen

Simple mucin-type carbohydrate antigens (T, Tn and sialosyl-Tn) in mucoepidermoid carcinoma of the salivary glands

Thirty-two cases of mucoepidermoid carcinoma of the salivary glands were studied in order to characterize the expression of simple mucin-type carbohydrate antigens T, Tn and sialosyl-Tn and to evaluate its implication for tumour histogenesis. Monoclonal antibodies of known specificity were used on formalin-fixed, paraffin-embedded tissue, and the expression of these antigens was studied in each of the three cell types (mucous, intermediate and squamous) as well as in the secretory content of neoplastic lumina. Aberrant glycosylation of simple-mucin type antigens was found in all cell types, as compared with that of normal excretory duct cells of the salivary glands. The more 'primitive' antigens Tn and sialosyl-Tn were present in a high percentage of epidermoid and intermediate cells. Mucous cells and the intraluminal secretory content also expressed Tn in 57.7% of the cases. This contrasts with the absence of secretion of these simple mucin type carbohydrates by normal salivary gland cells. Mucin-producing cells did not express T antigen but only sialosyl-T, in contrast to 57.1% and 56.3% respectively of the epidermoid and intermediate cell types. T and sialosyl-T were also found in the secretory products of the neoplastic lumina in 11.5% and 53.6% of the cases, respectively. The distinctive glycosylation pattern between mucin-producing cells on the one hand and intermediate and squamous cells on the other does not contradict the common origin of the three cell types from the reserve cell of the salivary excretory duct, but favours the proposition that intermediate cells constitute a step in the differentiation pathway of epidermoid, but not of mucin-producing, cells.

Carbohydrate antigen expression in murine embryonic stem cells and embryos. II. Sialylated antigens and glycolipid analysis

A mouse embryonic stem (ES) cell line E14 and early mouse embryos were stained with a panel of 15 monoclonal antibodies recognizing sialylated or potentially sialylated carbohydrate determinants. Sialyl Le-x and sialyl Le-a were detected on the pre-implantation embryo from the 8-cell stage, and sialyl Le-a weakly on undifferentiated ES cells. Changes in cell surface carbohydrates occurred after induction of ES cell differentiation with retinoic acid (RA) and dibutyryl cAMP. Qualitative analysis of the neutral glycolipids of untreated and RA-treated ES cells using high-performance thin-layer chromatography (HPTLC) revealed few differences between the two types of culture. The major gangliosides in both cultures were indicative of an active 'a' ganglioside synthesis pathway. GD3, a precursor of the 'b' synthesis pathway, previously reported to be characteristic of embryonal carcinoma (EC) cells, was absent. RA-induced differentiation caused a shift in the spectrum to more complex gangliosides. Application of fast atom bombardment mass spectrometry (FAB-MS) to permethylated derivatives of individual bands permitted partial characterization of an unusual sialylated glycolipid and a rare ganglioside with the suggested structure of GalNAc-GD1a.

Subtypes of non-transformed human mammary epithelial cells cultured in vitro: histo-blood group antigen H type 2 defines basal cell-derived cells

Normal (non-transformed) human mammary epithelial cell lines derived from reduction mammoplasties were analyzed by immunocytochemistry with more than 80 monoclonal antibodies (mAbs) and other specific reagents to tissue-specific and developmentally regulated antigens at different passage levels. A subpopulation of poorly differentiated, proliferating epithelial cells, corresponding to the 'selected' cell type of late passages, is shown to be characterized by a new marker, the histo-blood group antigen H type 2, probably carried on a membrane-bound glycolipid. These cells also express a number of other onco-developmental carbohydrate antigens [Le(y), Le(x), sialosyl-Le(a), precursor of Thomsen Friedenreich antigen (Tn), but not Thomsen-Friedenreich antigen and sialosyl-Tn]. Their cytokeratin (CK) phenotype, as assessed by reactivity with monospecific mAbs and two-dimensional gel electrophoresis, is CK 5, 6, 14 and 17, with CK 19 being consistently absent, and varying minor amounts of CK 7, 8 and 18, as well as 15 and 16. The reactivity of these cells with a panel of 11 mAbs specific for CK 18 varies considerably even after cloning, indicating heterogeneity of epitope expression or accessibility. Our data strongly suggest that the H type 2+ cells develop from the basal cell layer of the mammary gland.

Persistent repression of a functional allele can be responsible for galactosyltransferase deficiency in Tn syndrome

A human hematopoietic disorder designated as Tn syndrome or permanent mixed-field polyagglutinability has been ascribed to a stem cell mutation leading to a specific deficiency of UDP-Gal:GalNAc alpha 1-O-Ser/Thr beta 1-3 galactosyltransferase (beta 3 Gal-T) activity in affected cells. To test for the possibility that an allele of the beta 3Gal-T gene might be repressed instead of mutated, we have investigated whether 5-azacytidine or sodium n-butyrate, both inducers of gene expression, would reactivate expression of beta 3Gal-T in cloned enzyme-deficient T cells derived from a patient affected by the Tn syndrome. Flow cytometry revealed that a single treatment induced de novo expression of the Thomsen-Friedenreich antigen (Gal beta 1-3GalNAc-R), the product of beta 3Gal-T activity. In addition, a sialylated epitope on CD43 (leukosialin), which is present on normal but not on beta 3Gal-T-deficient T cells, was also reexpressed. Although no beta 3Gal-T activity was detectable in untreated Tn syndrome T cells, after exposure to 5-azaC,beta 3Gal-T activity reached nearly normal values. Both agents failed to reactivate beta 3Gal-T in Jurkat T leukemic cells, which also lack beta 3Gal-T activity. These data demonstrate that Tn syndrome T cells contain an intact beta 3Gal-T gene copy and that the enzyme deficiency in this patient is due to a persistent and complete but reversible repression of a functional allele. In contrast, the cause of beta 3Gal-T deficiency appears to be different in Jurkat T cells.

Simple mucin-type carbohydrate antigens in pleomorphic adenomas

Simple mucin-type carbohydrate structures, T, Tn and sialosyl-Tn, are regarded as general markers of carcinomas in several epithelial tissues as a result of incomplete synthesis with precursor accumulation. The structures have a very limited distribution in normal tissues and secretions, including saliva and salivary glands. The expression of simple mucin-type carbohydrate structures and ABH(O) variants was studied in paraffin-embedded and frozen tissue sections from 37 pleomorphic adenomas with associated normal parotid tissue, using immunohistology and a panel of MAbs with well-defined specificity for T, Tn, sialosyl-Tn, and blood group H and A variants hereof. The immature Tn and sialosyl-Tn antigen structures were expressed in the epithelial ductular structures of the tumors, whereas they were almost absent from normal parotid tissue, indicating aberrant glycosylation with accumulation of precursor structures. Furthermore, the tumors showed loss of A antigen. The prognostic significance of these results is discussed. The modified myoepithelial cells in periductular and solid areas expressed T and sialosyl-T antigens, similar to normal myoepithelial cells and basal cells. Thus these modified MEC seem to have retained their normal simple mucin-type glycosylation pattern, suggesting that T antigen may be used as a marker of MEC in salivary gland tumors.

Localization and identification of T-(Gal beta 1-3GalNAc alpha 1-O-R) and T-like antigens in experimental rat bladder cancer

A mouse monoclonal antibody and a rabbit polyclonal antibody against the T-antigen (Gal beta 1-3GalNAc alpha 1-O-R) were used to study the distribution of T-antigens in an experimental rat bladder cancer model. Neoplasia was induced in 28 rats by intravesical installation of N-nitroso-N-methylurea (NMU) dissolved in acetate buffer. Fifteen rats were installed with acetate buffer, and served as controls. Urothelial samples were taken from all animals, the atypia was graded and detailed data on the location of the antibody binding structures were obtained by immunohistochemical methods. In addition, Western Blots of glycoproteins and thin-layer-chromatography (TLC) immunostainings of glycolipids extracted from normal and malignant tissue were performed to characterize the molecules presenting T-antigens. Examination of the histologic distribution of T-antigens showed that both the monoclonal and the polyclonal reagents reacted with atypical cells in proportion to the grade of atypia, but showed no reaction in invasive cells. These results confirm previously obtained data on the T-antigen using peanut (arachis hypogaea) agglutinin (PNA), and support the structure identity as being the classical O-linked mucin type T-antigen. Western blots of tumor glycoproteins showed that the monoclonal and the polyclonal antibody reacted with epitopes different from that of PNA, but all the probes correlated with atypia. In addition PNA, as the only anti-T reagent, bound to glycolipid. By using well characterized and highly specific immunological reagents the present study shows that the T-antigen is a highly selective marker of urothelial atypia.

Binding of uropathogenic Escherichia coli R45 to glycolipids extracted from vaginal epithelial cells is dependent on histo-blood group secretor status

Women with a history of recurrent Escherichia coli urinary tract infections (UTIs) are two to three times more likely to be nonsecretors of histo-blood group antigens than are women without such a history. Further, uroepithelial cells from women who are nonsecretors show enhanced adherence of uropathogenic E. coli compared with cells from secretors. To investigate the hypothesis that nonsecretors express unique receptors for uropathogenic E. coli related to their genetic background, we extracted glycosphingolipids (GSLs) from vaginal epithelial cells collected from nonsecretors and secretors and used an assay in which radiolabeled uropathogenic E. coli were bound to these GSLs separated on TLC plates. An E. coli strain (R45) expressing both P and F adhesins, which was isolated from one of these patients' UTIs, was metabolically labeled with 35S for the TLC binding assay. The radiolabeled E. coli R45 bound to two extended globo-series GSLs, sialosyl gal-globoside (SGG) and disialosyl gal-globoside (DSGG), found in the GSL extracts from nonsecretors but not from secretors. The identity of SGG in the nonsecretor GSL extracts was confirmed in radioimmunoassays using an mAb to SGG and in immunofluorescence assays with this mAb and native vaginal epithelial cells. We show that SGG and DSGG are selectively expressed by epithelial cells of nonsecretors, presumably as a result of sialylation of the gal-globoside precursor glycolipid, which in secretors is fucosylated and processed to ABH antigens. The presence of SGG and DSGG may account for the increased binding of E. coli to uroepithelial cells from nonsecretors and for their increased susceptibility to recurrent UTI.

T cell clones with normal or defective O-galactosylation from a patient with permanent mixed-field polyagglutinability

To delineate the extent of O-galactosyltransferase deficiency within the lymphoid lineage, monoclonal antibody specific for the Thomsen-Friedenreich (TF) antigen (Gal beta 1----3GalNAc alpha 1-O-Ser/Thr) and its precursor the Tn antigen (GalNAc alpha 1-O-Ser/Thr) were applied to the flow cytometric analysis of peripheral blood lymphocytes from a patient with permanent mixed-field polyagglutinability (PMFP). We show that only a minor population of 4% expressed the Tn antigen which is in contrast to 93% of the patient's erythrocytes carrying the defect. Tn+ lymphocytes mainly belonged to the CD3+ subset, but were also CD19+ or CD16+. Both Tn+ and TF+ T cell clones from patient R. R. were established and shown to belong to the CD4+ or CD8+ antigenic subset. Three glycosyltransferase activities were determined in lysates from these clones: all Tn+ clones were deficient in UDP-Gal: GalNAc alpha 1-O-Ser/Thr beta 1----3 galactosyltransferase (beta 3Gal-T) activity; by contrast this activity was present in all lysates from TF-expressing clones. UDP-GalNAc: polypeptide alpha-N-acetylgalactosaminyltransferase (GalNAc-T) and UDP-Gal: GlcNAc-R beta 1----4 galactosyl-transferase (beta 4Gal-T) exhibited similar activities in both Tn+ and TF+ T cell clones. As a consequence of defective O-galactosylation in Tn+ T cells, cell surface sialic acid of Tn+ clones was reduced by greater than 50% when compared to TF+ clones as demonstrated by sialic acid-specific labeling using fluoresceinated Limax flavus agglutinin(LA) and flow cytometry. The Tn phenotype of T cell clones was stable for more than 1 year of continuous expansion in vitro. These data demonstrate that in PMFP, T cells may also be affected by the O-galactosyltransferase deficiency which is accompanied by a substantial loss of cell surface sialic acid. However, the frequency of Tn+ lymphocytes in peripheral blood from patient R.R. was strikingly low. These T cell clones should be useful to study the defect at a genetic level and the importance of O-linked carbohydrates for proper T cell function.

Primary structure of a Thomsen-Friedenreich-antigen-specific lectin, jacalin [Artocarpus integrifolia (jack fruit) agglutinin]. Evidence for the presence of an internal repeat

Jacalin [Artocarpus integrifolia (jack fruit) agglutinin] is made up of two types of chains, heavy and light, with M(r) values of 16,200 +/- 1200 and 2090 +/- 300 respectively (on the basis of gel-permeation chromatography under denaturing conditions). Its complete amino acid sequence was determined by manual degradation using a 4-dimethylaminoazobenzene 4'-isothiocyanate double-coupling method. Peptide fragments for sequence analysis were obtained by chemical cleavages of the heavy chain with CNBr, hydroxylamine hydrochloride and iodosobenzoic acid and enzymic cleavage with Staphylococcus aureus proteinase. The peptides were purified by a combination gel-permeation and reverse-phase chromatography. The light chains, being only 20 residues long, could be sequenced without fragmentation. Amino acid analyses and carboxypeptidase-Y-digestion C-terminal analyses of the subunits provided supportive evidence for their sequence. Computer-assisted alignment of the jacalin heavy-chain sequence failed to show sequence similarity to that of any lectin for which the complete sequence is known. Analyses of the sequence showed the presence of an internal repeat spanning residues 7-64 and 76-130. The internal repeat was found to be statistically significant.

The human repertoire of antibody specificities against Thomsen-Friedenreich and Tn-carcinoma-associated antigens as defined by human monoclonal antibodies

Human monoclonal antibodies specific for tumour-associated Thomsen-Friedenreich (TF) [Gal(beta 1-3)GalNAc(alpha)-O-] and Tn [GalNAc(alpha)-O-] glycoproteins were prepared using peripheral blood lymphocytes from healthy blood donors. The B lymphocytes were either directly transformed with Epstein-Barr virus (EBV) or transformed after an in vitro stimulation period with synthetic glycoproteins. The EBV-transformed lymphocytes were subsequently fused with a mouse-human heteromyeloma to secure antibody production and stability. IgM antibodies exhibiting different patterns of specificity for synthetic TF and Tn antigens were obtained, including antibodies specific for the alpha and beta forms of different Gal(beta 1-3)GalNAc-O- and GalNAc-O- conjugates and antibodies agglutinating neuraminidase-treated erythrocytes. Several of the human monoclonal antibodies showed an increased binding to cultured carcinoma cells as compared to melanoma cells. This straightforward approach for the production of human monoclonal antibodies demonstrates the possibility of investigating the reactivity pattern of tumour-binding antibodies from peripheral blood lymphocytes. The binding patterns of these monoclonal antibodies show that healthy donors carry different fine specificities against synthetic TF/Tn antigens and that these antibodies react with different tumour cells.

Nuclear volume and expression of T-antigen, sialosyl-Tn-antigen, and Tn-antigen in carcinoma of the human bladder. Relation to tumor recurrence and progression

The T-antigen system and the mean nuclear volume have been proposed as risk variables in bladder tumors. This study includes 34 patients with initially noninvasive (Ta) transitional cell carcinomas who experienced different courses of disease. Tissue specimens of primary tumors were analyzed for the expression of T-antigen, Tn-antigen, and sialosyl-Tn-antigen using monoclonal antibodies (MoAb) and the lectin peanut agglutinin (PNA) in an indirect immunoperoxidase method. In addition, the mean nuclear volume was estimated by morphometry. Tissue from 7 of 13 patients (54%) who had invasive disease during a follow-up period of 5 years expressed T-antigen, as defined by MoAb HH8 in the primary tumor, whereas tissue of only 3 of 21 patients who did not have invasive disease expressed the antigen (P less than 0.02). No association was found between tumor progression to invasion and the expression of Tn-antigen or sialosyl-Tn-antigen. Tn-antigen expression was partially lost in invasive tumors (P less than 0.03) when compared with the expression in primary noninvasive tumors. A high mean nuclear volume in tissue specimens of primary tumors correlated with a progression to invasive disease (P less than 0.01). A significantly (P less than 0.003) higher mean nuclear volume was found in tumor areas that were positive for PNA compared with areas that were negative for PNA in primary tumors. A significantly lower mean nuclear volume was found in Tn-antigen-positive invasive Grade 3 tumor areas than in Tn-antigen-negative areas (P less than 0.005). The combined use of T-antigen expression and mean nuclear volume is of potential clinical interest for determining patients who are at high risk of disease progression.

Simple mucin-type carbohydrates in oral stratified squamous and salivary gland epithelia

Simple mucin-type carbohydrate antigens, T, Tn, and sialosyl-Tn, have been found to be good markers of malignant transformation in several epithelial tissues as a result of incomplete synthesis with precursor accumulation. The T, Tn, and sialosyl-Tn antigens represent the initial, most immature glycosylation of serine and threonine amino acids of proteins. In normal adult cells these structures are generally masked by addition of further saccharides to form more complex structures. We analyzed simple mucin-type carbohydrates in human labial stratified squamous and minor salivary gland epithelia in order to define the glycosylation pattern in normal cells in relation to epithelial differentiation and maturation. A panel of monoclonal antibodies with well-characterized specificity for T, Tn, sialosyl-Tn and the histo-blood group H and A variants hereof were used in immunohistology of sections from 30 individuals with known ABO, Lewis, and secretor status. In stratified epithelium the sialylated T structure was confined to cell membranes of immature basal cells, whereas the H and A variants were observed on cell membranes of more mature parabasal and spinous cell layers. Furthermore, superficial spinous cells produced a fine granular cytoplasmic staining for Tn and sialosyl-Tn antigens. In minor salivary glands mucous cells expressed Tn and sialosyl-Tn as well as the H and A variants in the area of the nucleus, whereas T and the H variant were found in duct cells and unsubstituted T antigen in myoepithelial cells. These results indicate that incomplete synthesis, i.e., deletion of sialyltransferases and/or histo-blood group ABH transferases, may result in accumulation of T, Tn, and sialosyl-Tn antigens in oral epithelia, thus offering a baseline for further studies of changes in premalignant and malignant oral epithelia.

Expression of blood group-related carbohydrate antigens in normal human pancreatic tissue

The expression of type 1, 2 and 3 chain carbohydrate structures in 15 normal pancreata was investigated by immunohistochemical methods using well-defined monoclonal antibodies. Surgical biopsies of pancreata were obtained from kidney donors while the organs were still perfused. Type 1 chain structures were abundantly expressed including monosialylated(ms)- and disialylated(ds)-Le(a) antigens, which have previously been associated with cancer. Type 2 chain structures were represented by H and Le(y) antigens and to a lesser extent by the precursor structure N-acetyllactosamine, whereas Le(x), dimeric Le(x), and ms-Le(x) were only sporadically observed, in contrast to fetal pancreatic tissue, in which Le(x) has been found to be abundantly expressed. H chain 3 antigen was found in nearly all specimens, whereas precursor structures Tn, sial-Tn and T antigens were absent. Desialylation unmasked the T antigen in all specimens. Absence/masking of Tn, T and related antigens is of special interest, since these antigens are associated with tumor development in other tissues, and may be of importance in pancreatic cancer diagnostics in the future.

Further characterization of the saccharide specificity of peanut (Arachis hypogaea) agglutinin

2-Dansylamino-2-deoxy-D-galactose (GalNDns) has been shown to bind to peanut (Arachis hypogaea) agglutinin (PNA) in a saccharide-specific manner. This binding was accompanied by a five-fold increase in the fluorescence of GalNDns. The interaction was characterized by an association constant of 0.15 mM at 15 degrees and delta H and delta S values of -57.04 kJ.mol-1 and -118.1J.mol-1.K-1, respectively. Binding of a variety of other mono-, di- and oligo-saccharides to PNA, studied by monitoring their ability to dissociate the PNA GalNDns complex, revealed that PNA interacts with several T-antigen-related structures, such as beta-D-Galp-(1----3)-D-GalNAc, beta-D-Galp-(1----3)-alpha-D-GalpNAcOMe, and beta-D-Galp-(1----3)-alpha-D-GalpNAc-(1----3)-Ser, as well as the asialo-GM1 tetrasaccharide, with comparable affinity, thus showing that this lectin does not discriminate between saccharides in which the penultimate sugar of the beta-D-Galp-(1----3)-D-GalNAc unit is the alpha or beta anomer, in contrast to jacalin (Artocarpus integrifolia agglutinin), another anti T-lectin which preferentially binds to beta-D-Galp-(1----3)-alpha-D-GalNAc and does not recognize beta-D-Galp-(1----3)-beta-D-GalNAc or the related asialo-GM1 oligosaccharide. These studies also indicated that, in the extended combining region of PNA which accommodates a disaccharide, the primary subsite (subsite A) is highly specific for D-galactose, whereas the secondary subsite (subsite B) is less specific and can accommodate various structures, such as D-galactose, 2-acetamido-2-deoxy-D-galactose, D-glucose, and 2-acetamido-2-deoxy-D-glucose.

Histo-blood group antigens as differentiation markers in testicular germ cell tumours

The distribution of histo-blood group antigens in a series of eleven human non-seminomatous testicular germ cell tumours is described and the variable expression of these antigens is related to the patterns of differentiation that are reflected morphologically within these tumours. The results suggest that histo-blood group antigens of type 2 chain carbohydrate structures may be used as markers of differentiation. All the tumours contained binary 2-3 sialosyllactosamine structures. N-acetyllactosamine and Le(y)-negative tumors were the least differentiated morphologically, while N-acetyllactosamine and Le(y)-positive tumours exhibited more differentiated tumour patterns. Whether the occurrence of the latter antigens in poorly differentiated forms of germ cell tumours reflects a biological potential for differentiation remains to be proven in a larger material.

Human lung adenocarcinoma cell lines with different lung colonization potential (LCP), and a correlation between expression of sialosyl dimeric Le(x) (defined by MAb FH6) and LCP

Human lung adenocarcinoma sub-cell lines HAL-8, HAL-24 and HAL-33, showing different lung colonization potential (LCP), were established from human lung adenocarcinoma cell line KUM-LK-2 using repeated cloning with limiting dilution technique. Cell lines HAL-8 and -33 were characterized by high and low LCP, respectively, while HAL-24 did not give rise to lung colonies. The cell surface protein and carbohydrate profiles were determined by cell surface labeling (with lactoperoxidase-dependent 125I-iodination and galactose oxidase-NaB3H4, respectively) followed by SDS-gel electrophoresis. Various carbohydrate epitopes expressed at the cell surface were analysed by cytofluorometry using various monoclonal antibodies (MAbs) directed to Le(x), sialosyl-Le(x), sialosyl dimeric Le(x), T, Tn and sialosyl-Tn structures, which are often reported as being highly expressed in a variety of human cancers, particularly adenocarcinoma. Expression of sialosyl dimeric Le(x) (defined by MAb FH6) was high on HAL-8, moderate on HAL-33, and relatively low on HAL-24. In contrast, each of the three lines showed essentially equal expression (as determined by MAb reactivity) of sialosyl-Tn (defined by MAb TKH2), Le(x) (defined by MAb SH1), and Tn (defined by MAb 1E3). The cell lines showed extremely weak expression of T (defined by MAb HH8). LCP of HAL-8 and -33 was completely inhibited by sialidase treatment of cells. It is suggested that higher expression of sialosyl dimeric Le(x) (defined by MAb FH6) in HAL-8 cells may play an important role in higher potential of blood-borne lung colonization.

Expression of mucin type carbohydrates may supplement histologic diagnosis in oral premalignant lesions

Recent studies have shown that changes within membrane bound carbohydrates may be essential for cellular differentiation and malignant transformation. We have therefore, by means of immunohistochemistry, studied the expression of T/Tn related (Thomsen-Friedenrich) carbohydrates in 13 oral lesions with squamous cell dysplasia. The epithelial grade of dysplasia was graded as mild, moderate or severe. The following carbohydrate structures were studied: Tn, T, mucintype 3 chain H, and the sialylated derivates, sialosyl-Tn and sialosyl-T. In general, short structures were detected on the basal cells and longer structures on the more mature spinous cells. In many cases, this sequential expression was more disturbed with increasing grade of epithelial dysplasia. However, our results also showed that some lesions with the same grade of epithelial dysplasia showed different carbohydrate expression. These findings indicate that expression of carbohydrates may supplement histologic diagnosis in the evaluation of the prognosis of premalignant lesions.

Cellular localization of PNA binding in colorectal adenomas: comparison with differentiation, nuclear:cell height ratio and effect of desialylation

The lectin Arachis Hypogaea (Peanut Agglutinin, PNA) was used to study the cellular localization of the Thomsen-Friedenreich (T) disaccharide Gal-beta (1-3)-GalNAc alpha 1-R in 22 formalin-fixed paraplast-embedded colorectal adenomas of varying cellular dysplasia. An indirect immunoperoxidase method was used prior to and after neuraminidase treatment. Detailed information on the cellular localization of PNA binding was obtained. In addition, morphometric measurements of the nuclear: cell height ratios were performed on staining-filtered micrographs of crypts from all adenomas. We found 1) a statistically significant increase in the nuclear:cell height ratio with increasing grade of dedifferentiation (p less than 0.003), 2) a statistically significant smaller nuclear:cell height ratio in crypts that were PNA-positive in the Golgi region when these were compared to crypts that were PNA-positive on luminal cell membranes, 3) a decreasing number of crypts expressing PNA binding sites in the Golgi region with increasing dedifferentiation, leading to complete absence of PNA binding sites in Grade IV adenomas, 4) neuraminidase pretreatment increased the number of crypts expressing PNA binding sites in cytoplasm and on luminal membranes, whereas no changes were detected in crypts expressing PNA binding sites in the Golgi region. Our results confirm the general concept of accumulation of precursors of carbohydrate antigens in dedifferentiated cells. On the basis of the results presented, we conclude that the nuclear:cell height ratio shows a good correlation with the cellular localization of PNA binding, cellular differentiation and classic pathologic grading.

F11C antigen: a membrane marker able to distinguish two regressive and progressive variants from a rat colon adenocarcinoma

Cell variants that differ in their tumorigenicity and immunogenicity have been isolated from a BDIX rat colon adenocarcinoma cell line, DHD/K12. One variant, PRO, and the clones derived from it, are poorly immunogenic and induce progressive and metastatic tumors; the other one, REG, and its clones, are highly immunogenic and induce regressive tumors. When looking for a membrane marker distinguishing between PRO and REG lines, we obtained monoclonal hybridomas by immunizing BALB/c mice with PROb or REGb cell clones. Hybridoma F11C, producing an IgM monoclonal antibody (MAb) was able to distinguish between the cell variants on membrane immunofluorescence. All REGb cells strongly express F11C membrane antigen. On PROb cells, F11C antigen expression is weak, as demonstrated by cytofluorimetric analysis, and limited to a fraction of the cell population. The F11C membrane antigen is highly specific for the DHD/K12 cell line and the variants derived from it, but is not expressed on cells dissociated from the DHD transplanted tumor, from which DHD/K12 was established, suggesting that F11C antigen emerged during cell culture. Fluorescence absorption on synthetic oligosaccharides demonstrated that F11C antibody cross-reacts with A type 3, A type 4 and A type 5 chain blood group tetrasaccharides.

Expression of the histo-blood group ABO gene defined glycosyltransferases in epithelial tissues

The histo-blood group ABO carbohydrate antigens are differentially expressed in epithelia in close correlation with cellular differentiation. In order to gain insight into the biosynthetic regulation of these carbohydrate antigens, we correlated the expression of A carbohydrate antigens with that of the A gene defined glycosyl-transferase by immunohistology of human oral epithelia using monoclonal antibodies. In glandular epithelium the A transferase was found in mucous cells similar to that of the A carbohydrate antigens. In stratified non-keratinized squamous epithelium the A transferase was expressed only in spinous cell layers, which is in accordance with the appearance of the A carbohydrate antigens in these more mature cell layers. This simultaneous acquisition of the primary and secondary gene product of a glycosyltransferase gene, provides evidence that the well-defined sequential expression of histo-blood group carbohydrate antigens in stratified squamous epithelium may be directly regulated at the transcriptional level of the glycosyltransferase. Future studies will address the mechanism behind loss of A antigens in premalignant lesions and carcinomas.

Inhibition of human immunodeficiency virus (HIV) infection in vitro by anticarbohydrate monoclonal antibodies: peripheral glycosylation of HIV envelope glycoprotein gp120 may be a target for virus neutralization

Carbohydrate structures are often involved in the initial adhesion of pathogens to target cells. In the present study, a panel of anticarbohydrate monoclonal antibodies (MAbs) was tested for their ability to inhibit in vitro human immunodeficiency virus infectivity. MAbs against three different N- and O-linked carbohydrate epitopes (LeY, A1, and sialyl-Tn) were able to block infection by cell-free virus as well as inhibit syncytium formation. Inhibition of virus infectivity was independent of virus strain (HTLVIIIB or patient isolate SSI-002), the cell line used for virus propagation (H9 or MT4), and the cell type used as the infection target (MT4, PMC, or selected T4 lymphocytes). Inhibition was observed when viruses were preincubated with MAbs but not when cells were preincubated with MAbs before inoculation, and the MAbs were shown to precipitate 125I-labeled gp120. The MAbs therefore define carbohydrate structures expressed by the viral envelope glycoprotein gp120, indicating that glycans of the viral envelope are possible targets for immunotherapy or vaccine development or both.

O-linked mucin-type glycoproteins in normal and malignant colon mucosa: lack of T-antigen expression and accumulation of Tn and sialosyl-Tn antigens in carcinomas

The expression of carbohydrate core-structures on O-linked glycoproteins was examined in fetal (n = 6), infantile (n = 2), normal adult (n = 15), and malignant (n = 22) colorectal tissue by means of monoclonal antibodies (MAbs) specific for Tn (GalNAc alpha 1-O-R), sialosyl-Tn (NeuAc alpha 2-6GalNAc alpha 1-O-R), and T (Gal beta 1-3GalNAc alpha 1-O-R) antigens. Immunolabelling of solubilized malignant tissue, separated by SDS-PAGE, showed expression of Tn and sialosyl-Tn antigens on 3 molecules of similar mw (230, 210, and 170 kDa), whereas no T antigens could be detected. Immunohistochemical techniques showed that fetal colon mucosa expressed Tn antigens but no sialosyl-Tn antigens. Infantile colon mucosa, however, expressed Tn as well as sialosyl-Tn antigens, and normal adult colon mucosa cells expressed no Tn antigens but sialosyl-Tn in 2 out of 6 biopsies from cecum, which indicates occurrence post partum of alpha-6-NeuAc-transferase. Endothelium in normal adult mucosa showed expression of both Tn and sialosyl-Tn antigens; 82% of carcinoma tissue sections expressed Tn antigens, and 73% expressed sialosyl-Tn antigens in mucin or cytoplasm, or on luminal cell membranes. T antigens could be detected neither in normal mucosa cells at any stage of development, nor in carcinomas. The possibility exists that this could be due to masking of T antigen. Mucin-type blood-group A antigens which contain an internal T-disaccharide were demonstrated in 4 out of 4 A1 tumors by means of MAb HH5. However, urea-containing SDS-PAGE analysis demonstrated an HH5 binding to molecules different from those binding anti-Tn. In remote morphologically normal and abnormal crypts in colons from carcinoma patients, both Tn and sialosyl-Tn antigens were expressed in secreted mucin in 40% of the cases. The data indicate an expression of O-linked Tn and sialosyl-Tn core structures in fetal and infantile colon and in colorectal carcinomas.

Murine monoclonal antibodies directed to the human histo-blood group A transferase (UDP-GalNAc:Fuc alpha 1----2Gal alpha 1----3-N-acetylgalactosaminyltransferase) and the presence therein of N-linked histo-blood group A determinant

Mouse MAbs (WKH-1 through -3) to the human histo-blood group A glycosyltransferase (Fuc alpha 1----2Gal alpha 1----3 galactosaminyltransferase) were established by immunization with the purified native A transferase protein. Hybridomas were selected on the basis of solid-phase reactivity with the purified native A transferase, cell immunofluorescence and immunoprecipitation of transferase activity, and absence of reactivity with blood group ABH carbohydrate determinants. Three MAbs, thus selected, were found most likely to react with the protein epitopes unrelated to carbohydrate epitopes of purified A transferase. The MAbs reacted with cells having high A transferase activity and immunoprecipitated the A transferase activity as well as the 40,000 MW iodinated transferase protein. The antibodies were shown, however, to immunoprecipitate and partially inhibit not only A1 and A2 but also B transferase activity from plasma and A transferase from human lung, and to react with B cells expressing B transferase, thus indicating a cross-reactivity with B transferase. In contrast, they showed no reactivity with various cells having the O phenotype and did not immunoprecipitate the A transferase from porcine submaxillary glands or the alpha 1----2fucosyltransferase from Colo205 cells. The purified A glycosyltransferase was found to carry blood group A carbohydrate determinants by immunochemical detection with a panel of anti-carbohydrate MAbs. These determinants are believed to be N-linked, since treatment of the purified A transferase with N-glycanase removed activity. Immunohistological studies of three epithelial tissues showed that the antibodies stained the Golgi area of cells in epithelia from A and B, but not O, individuals.

Cell surface glycosylation patterns in psoriasis

Cell surface carbohydrates are excellent markers of cellular differentiation and maturation processes due to their great structural and antigenic diversity as well as their known biosynthetic precursor/product relationships. Using a panel of monoclonal antibodies with well-defined carbohydrate specificities we have studied the expression of biosynthetically related antigens in normal and psoriatic skin. Two "families" of carbohydrate structures were investigated. One series of structures based on N-acetyllactosamine chains (type 2 chain: N-acetyllactosamine and fucosylated derivates hereof of H, Lex, Ley and sialyl-Lex) and another based on the simple mucin type core structures (type 3 chain: Tn, T and sialylated derivates hereof as well as the fucosylated derivative, H). Previously we have found these carbohydrate structures define distinct cell layers in stratified squamous epithelia of mucosa of the cheek, esophagus and uterine cervix. In normal and uninvolved epidermis, N-acetyllactosamine and T carbohydrates were found in the spinous cell layer, whereas the fucosylated derivates, H structures, were found in the granular cell layers above. The fucosylated and sialylated derivate of N-acetyllactosamine, sialylated Lex, had the same distribution as N-acetyllactosamine and T structures. This sequential expression of carbohydrates is similar to our previous findings in mucosa. However, in contrast to mucosa, normal skin basal cells did not label. The glycosylation pattern in psoriatic epithelium was changed in two ways. 1) Some carbohydrates (types 2 and 3 chain H and T) were expressed at an earlier stage of cell maturation. 2) The biosynthetic precursors to T structures, Tn and sialyl-Tn, which are not expressed in normal skin, and are often considered cancer-associated antigens, appeared in psoriatic skin. The Tn-antigen was expressed on basal and lower spinous cells, whereas the sialyl-Tn was only found on basal cells above the dermal papillae. The findings in the present work support previous studies of changes in cell surface glycosylation in psoriatic epidermis and demonstrate the appearance of tumor-associated antigens in highly proliferative, but benign, stratified epithelium.

Topography of the combining region of a Thomsen-Friedenreich-antigen-specific lectin jacalin (Artocarpus integrifolia agglutinin). A thermodynamic and circular-dichroism spectroscopic study

Thermodynamic analysis of carbohydrate binding by Artocarpus integrifolia (jackfruit) agglutinin (jacalin) shows that, among monosaccharides, Me alpha GalNAc (methyl-alpha-N-acetylgalactosamine) is the strongest binding ligand. Despite its strong affinity for Me alpha GalNAc and Me alpha Gal, the lectin binds very poorly when Gal and GalNAc are in alpha-linkage with other sugars such as in A- and B-blood-group trisaccharides, Gal alpha 1-3Gal and Gal alpha 1-4Gal. These binding properties are explained by considering the thermodynamic parameters in conjunction with the minimum energy conformations of these sugars. It binds to Gal beta 1-3GalNAc alpha Me with 2800-fold stronger affinity over Gal beta 1-3GalNAc beta Me. It does not bind to asialo-GM1 (monosialoganglioside) oligosaccharide. Moreover, it binds to Gal beta 1-3GalNAc alpha Ser, the authentic T (Thomsen-Friedenreich)-antigen, with about 2.5-fold greater affinity as compared with Gal beta 1-3GalNAc. Asialoglycophorin A was found to be about 169,333 times stronger an inhibitor than Gal beta 1-3GalNAc. The present study thus reveals the exquisite specificity of A. integrifolia lectin for the T-antigen. Appreciable binding of disaccharides Glc beta 1-3GalNAc and GlcNAc beta 1-3Gal and the very poor binding of beta-linked disaccharides, which instead of Gal and GalNAc contain other sugars at the reducing end, underscore the important contribution made by Gal and GalNAc at the reducing end for recognition by the lectin. The ligand-structure-dependent alterations of the c.d. spectrum in the tertiary structural region of the protein allows the placement of various sugar units in the combining region of the lectin. These studies suggest that the primary subsite (subsite A) can accommodate only Gal or GalNAc or alpha-linked Gal or GalNAc, whereas the secondary subsite (subsite B) can associate either with GalNAc beta Me or Gal beta Me. Considering these factors a likely arrangement for various disaccharides in the binding site of the lectin is proposed. Its exquisite specificity for the authentic T-antigen, Gal beta 1-3GalNAc alpha Ser, together with its virtual non-binding to A- and B-blood-group antigens, Gal beta 1-3GalNAc beta Me and asialo-GM1 should make A. integrifolia lectin a valuable probe for monitoring the expression of T-antigen on cell surfaces.

Expression of blood group antigen-related carbohydrates by human gingival epithelia

A panel of monoclonal antibodies was used to examine differentiation-related carbohydrate structures on the surfaces of gingival epithelial cells. The patterns of binding observed indicate distinct differences in the expression of the epitopes examined for three regions of the gingival epithelia corresponding approximately to the regions defined anatomically as the junctional, oral sulcular and oral epithelia. However, epithelium with the staining pattern of oral sulcular epithelium consistently extended beyond the sulcular region to cover the gingival crest and often the uppermost part of the oral aspect of the gingiva. Differential staining of basal and suprabasal cells indicated an unusual pattern of differentiation of the junctional epithelium. The phenotype of this epithelium appears to differ from patterns reported for any other oral epithelium and the possible functional significance of this difference is discussed.

Are pancarcinoma T and Tn differentiation antigens?

Human fetal tissues were studied for presence of immunoreactive Thomsen-Friedenreich (T) and Tn epitopes (EPs) using well-defined anti-T and anti-Tn rodent monoclonal antibodies. T and Tn are universal (pan) carcinoma (CA) markers that are occluded in normal postfetal tissues except in some immunoprivileged enclaves. Immunohistochemical methods using avidin-biotin immunoperoxidase for staining were employed. Tissues between 45 and 117 days after ovulation were studied. In most instances, anti-T and anti-Tn antibodies showed similar immunoreactivity as demonstrated by positive immunohistochemical staining. The most intense staining was in epithelial and mesothelial components; the mesenchyme stained more faintly. All human sera have anti-T and anti-Tn antibodies, stimulated largely by intestinal flora. The presence of immunoreactive T and Tn during an early phase of fetal development, as shown here, and their known absence in noncarcinomatous postfetal tissues suggests that T and Tn, in addition to their association with CA, are stage-specific oncofetal antigens in pretolerogenic differentiation phases.

Coexpression of sialosyl-Tn (NeuAc alpha 2----6GalNAc alpha 1----O-Ser/Thr) and Tn (GalNAc alpha 1----O-Ser/Thr) blood group antigens on Tn erythrocytes

Polyagglutinable erythrocytes expressing the rare human blood group phenotype Tn were tested for expression of both Tn (GalNAc alpha 1----O-Ser/Thr) and sialosyl-Tn (NeuAc alpha 2----6GalNAc alpha 1----O-Ser/Thr) antigens by agglutination with a panel of well-characterized monoclonal antibodies specifically directed to Tn and sialosyl-Tn antigens, respectively. Tn erythrocytes from 4 patients were strongly agglutinated by both sialosyl-Tn and Tn-specific monoclonal antibodies, indicating coexpression of sialosyl-Tn and Tn antigens on the cell membrane surface of Tn polyagglutinable erythrocytes. Human polyclonal anti-Tn antisera were found to express weak and variable anti-sialosyl-Tn antibodies in conjunction with the anti-Tn antibodies. The Tn phenotype thus involves not only the classically known Tn antigens but also sialosyl-Tn antigens. However, the human anti-Tn antibodies may be directed mainly toward the Tn antigen (GalNAc alpha 1----O-Ser/Thr).

Development of an ABO-ELISA for the quantitation of human blood group anti-A and anti-B IgM and IgG antibodies

An indirect ELISA system was designed for quantitation of human blood group A and B IgM and IgG antibodies. The capturing antigens are blood group substance A or B used to sensitize polystyrol microtiter plates. Bound anti-A or anti-B antibodies are revealed either directly, by development with polyclonal anti-human immunoglobulin class-specific conjugate or with more avid mouse monoclonal anti-human isotype antibodies revealed in turn by goat anti-mouse conjugate. Reproducibly, 100 ng specific anti-A IgG provided for a significant above-background signal of 0.2 at OD405 and 15 serum samples had a mean content of 3.98 +/- 8.74 micrograms (mean +/- 2 SD) (range: 0.305-12.62) of specific anti-A IgG/g total IgG. Thus one molecule specific anti-A IgG is found per 7.9 X 10(4)-3.2 X 10(6) total IgG molecules. Statistical correlations were significant between anti-A IgG levels and agglutination titer (P less than 0.05) but non-significant when the specific anti-A IgG levels of individual serum samples were compared to their total IgG content (P greater than 0.05). Dose-response signals were similar for anti-A and anti-B IgM antibodies. Reproducibility of the assay was excellent. Specificity was ascertained by various approaches involving development of primary antibodies with heterospecific antibody conjugate and adsorption of primary antibody from serum using A and B group erythrocytes or soluble A and B substances. Separation of IgM from IgG anti-A antibodies over sizing gel resulted in fractions that were immunosorbed by mouse monoclonal anti-human IgM and IgG respectively but not vice versa.

ABH and related histo-blood group antigens; immunochemical differences in carrier isotypes and their distribution

This review summarizes present knowledge of the chemistry of histo-blood group ABH and related antigens. Recent advances in analytical carbohydrate chemistry (particularly mass spectrometry and NMR spectroscopy) and the introduction of monoclonal antibodies (MoAbs) have made it possible to distinguish structural variants of histo-blood group ABH antigens. Polymorphism of ABH antigens is induced by: (i) variations in peripheral core structure, of which four (type 1, 2, 3 and 4) are known in man; (ii) variation in inner core by branching process (blood group iI), leading to variation of unbranched vs. branched ABH determinants; (iii) biosynthetic interaction with other glycosyltransferases (Lewis, P. T/Tn blood systems) capable of acting on the same substrate as the ABH-defined transferases, and finally (iv) the nature of the glycoconjugate (glycolipid, glycoprotein of N- or O-linked type). ABH variants induced by item (i) above have been clearly distinguished qualitatively by MoAbs; e.g., at least six types of A determinants can be distinguished by qualitatively different classes of antibody. The variants induced by item (ii) create mono- vs. bivalent antigens which may be responsible for observed differences in antibody-binding affinity. Detailed studies of the chemistry of these antigens have increased our insight into blood groups, providing the basis for blood group iI and A subgrouping, as well as a relation between the ABH and Lewis, P, and T/Tn systems. A survey of the literature on distribution patterns of ABH variants is presented. It has been assumed that expression of histo-blood group antigens is developmentally regulated. Relationships between histo-blood group expression, development, differentiation and maturation, as well as malignant transformation, are discussed.

Blood group related carbohydrate antigens in human fetal pancreas

Many tumor-associated carbohydrate antigens are related to the blood group systems. Since several of these antigens are developmentally regulated, a systematic knowledge of the expression of blood group related carbohydrate antigens during organogenesis is important. By immunohistochemical methods we investigated the expression of carbohydrate structures related to the ABH, Lewis, T and Tn blood group systems in 28 fetal pancreas, from 13th-40th gestational week using a comprehensive set of well-defined monoclonal antibodies, reacting with type 1, 2, 3, and 4 chain carbohydrate structures. The following antigens were found in fetal pancreas: Type 1 chain: Lea, Leb, monosialylated Lea and disialylated Lea, type 2 chain: N-acetyllactosamine (the immediate precursor to blood group H antigen), branched N-acetyllactosamine, H-antigen, Lex and Ley; type 3 chain: H-antigen. The T-antigen was well expressed, whereas this was not the case with the Tn-antigen. As expected the A-antigen was found in 10 of 24 cases. The A-related antigens: ALeb, ALed and ALey were only found in a few of these ten specimens whereas type 3 chain A-repetitive was found in all of them. Since msLea, Lex, Ley and T-antigen have been described as tumor-associated antigens, we conclude that several carbohydrate tumorrelated antigens are expressed in fetal pancreas.