Ley Antigens Research Articles

Comparative immunological studies of tumor-associated Lewis X, Lewis Y, and KH-1 antigens

Tumor-associated carbohydrate antigens Lewis X (Lex), Lewis Y (Ley), and KH-1 are useful targets for cancer immunotherapy. In this regard, an insight into the structure-immunogenicity relationships of these antigens is important but this has not been systematically investigated yet. In the current study, Lex, Ley, and KH-1 antigens with a lactose unit at the reducing end as a spacer were synthesized and coupled with keyhole limpet hemocyanin (KLH) protein. Immunological evaluations of the resultant conjugates revealed that they all could elicit robust immune responses whilst the Ley conjugate could provoke the highest titers of total and IgG antibodies. The binding assays of their antisera to each antigen and to cancer cells showed that each antiserum had extensive cross-reaction with all three antigens as protein conjugates and strong but somewhat antigen-selective binding towards MCF-7 cancer cell. Moreover, none of these antisera had obvious binding to SKMEL-28 cancer cell that does not express Lex, Ley and KH-1. The results of assays of these antisera to mediate complement-dependent cytotoxicity (CDC) to MCF-7 and SKMEL-28 cancer cells were very similar to the results of binding assays. Thus, it was concluded that all three antigens could form effective conjugate vaccines whereas the Ley conjugate induced the most robust immune responses and the antiserum of Lex had the highest binding and cytotoxicity to target cancer cells. In addition, as the antibodies induced by each antigen had extensive cross-reaction with other two antigens, either Lex or Ley or the two combined can be utilized to formulate effective conjugate vaccines for cancer immunotherapy. Another paradigm-shifting discovery of this study is that the presentation of Lex, Ley, and KH-1 antigens on cancer cell can be different from that in synthetic conjugates, which should be taken into consideration during the design and optimization of related cancer vaccines or immunotherapies.

Highly flexible, IgG-shaped, trivalent antibodies effectively target tumor cells and induce T cell-mediated killing.

A novel bispecific antibody format was applied to generate T cell-engaging antibodies. The TriFab format is a trivalent IgG-shaped entity composed of two Fab arms that bind to antigens on the surface of tumor cells, which are linked via flexible peptides to a CD3 binding moiety that replaces the CH2 domains of conventional IgGs. The distinctive feature of these T cell recruiting bispecifics is that their CD3 variable regions are incorporated between domains, rather than N- or C-terminally fused to an Fc or antibody fragments. T cell recruiting TriFabs resemble in size and shape, are expressed and show biophysical properties similar to regular IgGs. Transmission electron microscopy (TEM) demonstrates high flexibility of the cell surface binding arms as well as target antigen accessibility of the interspersed CD3 binding domain. Functional co-culturing assays of peripheral blood mononuclear cells (PBMCs) and different tumor cell lines (MCF7 and A431) revealed a dose-dependent T cell-mediated cytotoxicity that was induced by the TriFabs targeting either LeY or EGFR cell surface antigens.

Unusual N-type glycosylation of salivary prolactin-inducible protein (PIP): multiple LewisY epitopes generate highly-fucosylated glycan structures.

Prolactin-inducible protein (PIP) is a glycoprotein found in body secretions from exocrine glands like saliva and seminal plasma. Important biological functions of PIP concentrations have been demonstrated, e.g. in tumor diagnosis and progression. PIP quantity has been also found useful to determine the success of chemotherapy of mammary carcinoma. Here, we present the analysis of the N-glycosylation of PIP isolated from different sources by LC-MS(/MS) and 1H-NMR. We found a very uncommon N-type glycosylation of PIP in healthy individuals from both, seminal fluid and saliva. PIP carries unusual highly fucosylated N-linked glycans with multiple Lewisy (Ley) epitopes on bi-, tri- and tetraantennary structures resulting in up to nine fucosyl residues on a tetraantennary glycan. In most organs, Ley epitopes are not present on N-glycans except in case of a tumor when it is highly up-regulated and important for prognosis. Here, for the first time on a specific glycoprotein Ley antigens are unambiguously characterized on an N-type glycan by NMR spectroscopy. So far, for specific glycoproteins Ley epitopes had only been reported on O-glycans. Furthermore, a correlation between a nonsynonymous single nucleotide polymorphism (SNP) and glycosylation pattern was detected: individuals heterozygous for the SNP causing the amino acid exchange 51Gln to 51His have glycan structures with a higher degree of sialylation compared to individuals lacking the SNP.

Inflammatory cytokines regulate the expression of glycosyltransferases involved in the biosynthesis of tumor-associated sialylated glycans in pancreatic cancer cell lines

BackgroundPancreatic ductal adenocarcinoma (PDAC) is characterized by an abundant stroma containing several pro-inflammatory cytokines, which are described to modulate the expression of important genes related to tumor promotion and progression. In the present work we have investigated the potential role of these cytokines in the biosynthesis of tumor-associated carbohydrate antigens such as sialyl-Lewisx (SLex) through the regulation of specific glycosyltransferase genes. MethodsTwo human PDAC cell lines MDAPanc-3 and MDAPanc-28 were treated with pro-inflammatory cytokines IL-1β, TNFα, IL-6 or IL-8, and the content of tumor-associated carbohydrate antigens at the cell membrane was analyzed by flow cytometry. In addition, variation in the mRNA expression of sialyltransferase (ST) and fucosyltransferase (FUT) genes, which codify for the ST and FucT enzymes involved in the carbohydrate antigens’ biosynthesis, was determined. The inflammatory microenvironment of PDAC tissues and the expression of Lewis-type antigens were analyzed by immunohistochemistry to find a possible correlation between inflammation status and the presence of tumor-associated carbohydrate antigens. ResultsIL-1β stimuli increased SLex and α2,6-sialic acid levels in MDAPanc-28 cells and enhanced the mRNA levels of ST3GAL3-4 and FUT5-7, which codify for ST and FucT enzymes related to SLex biosynthesis, and of ST6GAL1. IL-6 and TNFα treatments increased the levels of SLex and Ley antigens in MDPanc-3 cells and, similarly, the mRNA expression of ST3GAL3-4, FUT1-2 and FUT6, related to these Lewis-type antigens’ biosynthesis, were increased. Most PDAC tissues stained for SLex and SLea and tended to be expressed in the tumor samples with a higher presence of inflammatory immune cells. ConclusionsThe inflammatory microenvironment can modulate the glycosylation pattern of PDAC cells, increasing the expression of tumor-associated sialylated antigens such as SLex, which contributes to pancreatic tumor malignancy.

Polyvalent vaccine-KLH conjugate and OPT-821 with bevacizumab (BEV) in patients with ovarian cancer in second or greater remission.

5550 Background: We previously completed a phase I study of a polyvalent vaccine containing GM2, Globo-H, LeY, Tn-MUC1, Tn(c), STn(c) and TF(c) antigens (AGs) individually conjugated to KLH and mixed with adjuvant OPT-821. We showed safe induction of antibody (ab) responses to 5 of the 7 vaccine AGs. Data has shown that tumor vaccine efficacy may be enhanced through disruption of angiogenesis thus providing a rationale for combining BEV with the polyvalent vaccine. We conducted an IRB-approved pilot study to evaluate the safety and immunogenicity of the poly-KLH-vaccine when given with BEV in OC in remission. Methods: Pts with recurrent OC in ≥2nd complete or partial remission were enrolled from 12/2010-03/2012. Pts received 6 vaccines and BEV over 17 weeks. BEV was continued beyond the vaccination phase. Treatment was continued until disease progression or toxicity. Serologic IgM and IgG responses were measured by ELISA against each AG. Wilcoxon signed rank test was used to test changes in cytokines (CKs): FGFβ, IL-8, PDGF, VEGF measured by angio multiplex assay. Results: n=21 Median age 56yrs (51-70). 2, 8, 8, 3 pts were in 2nd, 3rd, 4th, 5th remission, respectively. 1 DLT (gr 4 fever post vaccine #2). Immune Results: n=19 IgG +/or IgM: ≥3 AGs in 17pts. IgM: ≥1 AG in 19pts, ≥3 AGs in 15pts. IgG: ≥1 AG in 17pts, ≥3 AGs in 3pts. CK Results: In 10 pts who completed 6 vaccines there was a mean (median) decrease in VEGF of 144 (111) pg/ml at the 17-week timepoint compared to baseline (p=0.05). For 8 pts who did not complete all 6 vaccines there was a mean (median) increase of 76 (69) pg/ml compared to baseline at the off-study visit (p=0.16). There was no statistically significant change in the other CKs compared to baseline values. At last follow-up, 18 pts had recurred and 3 pts had died. The median PFS was 5.6mths. Conclusions: 89% of pts responded to ≥3 AGs comparable to the 89% response in our prior phase I trial without BEV. BEV and polyvalent-KLH vaccine can be safely administered together with retention of the vaccine’s immunogenicity. Serum VEGF levels decreased in patients on continued BEV therapy. Clinical trial information: NCT01223235. [Table: see text]

Structure of the Lectin Regulatory Domain of the Cholesterol-Dependent Cytolysin Lectinolysin Reveals the Basis for Its Lewis Antigen Specificity

The cholesterol-dependent cytolysins (CDCs) punch holes in target cell membranes through a highly regulated process. Streptococcus mitis lectinolysin (LLY) exhibits another layer of regulation with a lectin domain that enhances the pore-forming activity of the toxin. We have determined the crystal structures of the lectin domain by itself and in complex with various glycans that reveal the molecular basis for the Lewis antigen specificity of LLY. A small-angle X-ray scattering study of intact LLY reveals the molecule is flat and elongated with the lectin domain oriented so that the Lewis antigen-binding site is exposed. We suggest that the lectin domain enhances the pore-forming activity of LLY by concentrating toxin molecules at fucose-rich sites on membranes, thus promoting the formation of prepore oligomers on the surface of susceptible cells.

Real-Time Label Free Analysis of Native Bacterial Cells Binding to Carbohydrate Microarray

We present a novel experimental system based on glycoconjugates microarray and oblique-incidence reflectivity difference (OI-RD) microscopy to analyze binding of the onco-pathogen Helicobacter pylori to surface immobilized carbohydrates. The results confirm the recognized high-affinity binding of H. pylori BabA to the fucosylated Leb antigen, and suggest the presence of additional Leb binding adhesins not previously detected. OI-RD microscopy is a recently developed method for analyses of label-free biomolecules binding to immobilized targets by measuring small changes in phase and amplitude of a reflected optical wave from a solid surface due to the reaction of a solution-phase probe with the target. Besides applications of OI-RD in DNA hybridization, antigen-antibody interactions and small molecule libraries screening, we apply OI-RD microscopy to the binding analyses of whole bacterial cells to their host receptors presented on surfaces. Glycoconjugates microarrays consisting of Lea-HSA, Leb-HSA, Lex-HSA, and Ley-HSA were probed with H. pylori, H. pylori BabA deletion mutant and recombinant BabA protein. H. pylori demonstrated specific binding to Leb antigen, but did not bind to the closely related Lea, Lex or Ley antigens. The specificity in binding to the Leb antigen and not to Lea, Lex or Ley antigens was faithfully reproduced by recombinant BabA protein. Besides, H. pylori BabA deletion mutant does not express BabA and does not bind to Leb-HSA in solution, also demonstrated specific albeit reduced binding to Leb antigen. These results suggest that some H. pylori strains exhibit a complementary Leb-binding activity (independent of BabA) that has not been previously detected. The OI-RD technology with real-time analyses of whole cell bacterial binding to multivalently presented receptors in solid phase combined with magnified sensitivity for weaker adherence properties, offers new possibilities for identification of discrete attachment mechanisms essential for the infectious.

α(1,2)fucosylation in human colorectal carcinoma

Lewis(b) and Lewis(y) (Le) antigens are known to be elevated in colorectal tumours. Alterations in the catalytic behaviour of GDP-L-fucose:β-D-galactoside α(1,2)fucosyltransferase [α(1,2)FT, EC: 2.4.1.69], the key enzyme in their synthesis, have been suggested as being responsible for these changes. In particular, an aberrant tumour-specific α(1,2)FT activity that converts Le(a) and Le(x) to Le(b) and Le(y) determinants, respectively, has been reported in colorectal cancer tissues. To clarify the catalytic function of this enzyme during colorectal tumorigenesis, we analyzed α(1,2)FT activity levels in healthy and tumour colon specimens using different acceptor substrates and determined the kinetic properties of the enzyme. To complete the study, the aberrant Le(a)/Le(x) α(1,2)fucosylation was determined in healthy and tumour colorectal tissues. A correlation analysis between the activity levels and various standard clinicopathological features, such as tumour stage, was also carried out to elucidate the role of these activities in tumour progression. The results obtained confirm the enhanced α(1,2)fucosylation in colorectal neoplastic tissues and the importance of the aberrant Le(a)/Le(x) α(1,2)FT activity in this increase. However, taking into account the high levels of Le(a)/Le(x) fucosylation observed in healthy control tissues, we must rule out the idea of a colorectal tumour-specific α(1,2)FT. On the other hand, no significant association was observed between α(1,2)FT activity levels and the clinicopathological characteristics. Overall, our results suggest that α(1,2)FT activity plays a critical role in the accumulation of Le(b) and Le(y) antigens in human colorectal carcinoma.

Losses of expression of the antigens A, Lea and Lex and over-expression of Ley in carcinomas and HG-SIL of the uterine cervix.

BackgroundThe glycosylation of a great number of molecules, glyco-protein or glycolipids, has been of interest for decades.ObjectiveTo compare the expressive patterns of the isoantigenic determinants of histo-blood groups ABH and Lewis in squamous and simple epithelium and in precursors and cancers of the cervix.MethodsA total of 36 lesions and neoplasms (10 LG-SIL, 16 HG-SIL and 10 invasive carcinomas) have been studied with immunohistochemical techniques, using monoclonal antibodies (MoAb BG1 to BG8) for precursor chains, blood-group ABH and Lewis group Lea, Leb, Lex, and Ley, and four types of lectins. In addition, we have studied the expression of p53 protein and PCNA, establishing the rate of proliferation of each lesion. Using PCR techniques, we have also detected part of the intron of the E6 gene of HPV-16.ResultsIn the invasive cervical carcinomas, we observed a loss of expression of the Lex antigen (p < 0.01). With regard to the progression of the different lesions studied, we found alterations in the patterns of expression of the antigens of the ABH and Lewis blood groups. There was a tendency towards a loss of expression and heterogeneous patterns in the more advanced lesions, as well as over-expression of the Ley antigens. With PCNA, we established a proliferative rate which tended to be greater in relation to the progression of the cervix neoplasms.ConclusionThese results indicate that there is a relation between the losses of histo-blood groups and the progression of the squamous intraepithelial lesions.

Ultrastructural localization of glycodelin oligosaccharides Le‐x and Le‐y in human seminal vesicles by immunogold staining

Histo-blood group antigens Le-x and Le-y are oligosaccharidic terminals that characterize many glycoproteins in the human tissues. In seminal plasma, they are expressed as part of the so-called glycodelin S, which is suggested to regulate sperm capacitation/decapacitation. It has recently been demonstrated that the core protein of glycodelin S is secreted by seminal vesicles. Here we show that epithelial cells of human seminal vesicles also release the Le-x and Le-y antigens. The presence of these substances in secretory material was revealed by means of an immunogold staining method in normal surgical samples. The results suggest that glycodelin S is secreted by seminal vesicles in its finished glycosylated form. Moreover, antigen reactivity was also revealed associated with plasma membranes.

Three‐dimensional structures of carbohydrate determinants of Lewis system antigens: Implications for effective antibody targeting of cancer

Lewis system carbohydrate antigens have been shown to be expressed at high levels in many cancers of epithelial cell origin, including those of colon, breast, lung, prostate and ovary. The type 1 (Le(a) and Le(b)) antigens are important histo-blood groups, while type 2 (Le(x) and Le(y)) antigens in healthy individuals are only expressed, at relatively low levels, by a few tissues, including some epithelial cells. Thus, the type 2 antigens are considered to be tumour-associated antigens and are promising targets for cancer treatment, including antibody-based immunotherapy. In this review, we discuss the conformational characteristics of the free and bound forms of Lewis oligosaccharides and the 3D structures of antibodies in complex with Le(y) and Le(x) antigens. Collectively, the structural studies have demonstrated that the Lewis determinants are rigid structures, which generally maintain the same conformation in the free and bound states. The rigid nature and similarities in shape of type 1 and 2 Lewis oligosaccharides appear to make them perfectly suited to driving a structurally convergent immune response (at least in the case of Le(y) specific antibodies) toward a highly specific recognition of individual carbohydrate determinants, which is a goal in the development of effective antibody-based cancer treatments.

Structural Convergence of Antibody Binding of Carbohydrate Determinants in Lewis Y Tumor Antigens

Antibodies targeting human epithelial carcinomas bearing Lewis Y (Ley) carbohydrate antigens provide a striking illustration of convergent immune recognition. We report a 1.9Å resolution crystal structure of the Fab of a humanized antibody (hu3S193) in complex with the Ley tetrasaccharide, Fuc(α1→2)Gal(β1→4)[Fuc(α1→3)]GlcNAc. Comparisons of the hu3S193 and BR96 antibodies bound to Ley tumor antigens revealed extremely similar mechanisms for recognition of the carbohydrate epitopes. Solvent plays a critical role in hu3S193 antibody binding to the Ley carbohydrate epitope. Specificity for Ley is maintained because a conserved pocket accepts an N-acetyl group of the core Gal(β1→4)GlcNAc disaccharide. Closely related blood-group determinants (Lea and Leb) cannot enter the specificity pocket, making the Ley antibodies promising candidates for immunotherapy of epithelial cancer.

The expression of human FUT1 in HT-29/M3 colon cancer cells instructs the glycosylation of MUC1 and MUC5AC apomucins.

Recently, we have reported that in normal gastric epithelium, the expression of gastric apomucins MUC5AC and MUC6 is associated with the specific expression of type 1 and type 2 Lewis antigens, and FUT2 and FUT1 fucosyltransferases, respectively. Until now, there are no data demonstrating the direct implication of specific glycosyltransferases in the specific patterns of apomucin glycosylation. HT29/M3 colon cancer cell line express MUC1, MUC5AC, type 1 Lewis antigens and FUT2 but not type 2 structures and FUT1, as it occurs in the epithelial cells of the gastric superficial epithelium. These cells were transfected with the cDNA of human FUT1, the alpha-1,2-fucosyltransferase responsible for the synthesis of type 2 Lewis antigens, to assess the implication of FUT1 in the glycosylation of MUC1 and MUC5AC. The M3-FUT1 clones obtained express high levels of type 2 Lewis antigens: H type 2 and Ley antigens. Immunoprecipitation of MUC1 and MUC5AC apomucins gives the direct evidence that FUT1 catalyses the addition of alpha-1,2-fucose to these apomucins, supporting the hypothesis that the pattern of apomucin glycosylation is not only instructed by the mucin primary sequence but also by the set of glycosyltransferases expressed in each specific cell type.

Expression of Carbohydrate Antigens in Advanced-Stage Ovarian Carcinomas and Their Metastases—A Clinicopathologic Study

Objective. Up-regulated expression or loss of expression of various carbohydrate antigens on the surface of cancer cells has been associated with a metastatic phenotype and poor survival in epithelial malignancies of different origins. The object of this study was to investigate the expression of carbohydrate antigens in two groups of patients diagnosed with advanced-stage ovarian carcinoma—one with an extremely favorable outcome and the other with a uniformly poor survival.Methods. Sections from 76 paraffin-embedded blocks (primary ovarian carcinomas and metastatic lesions) from 45 patients diagnosed with advanced-stage ovarian carcinomas (FIGO stages III–IV) were immunohistochemically stained using five monoclonal antibodies for Lewisy (Ley)(two antibodies), Sialyl Lewisx (Slex), Tn, and Sialyl Tn (STn) antigens. Patients were divided in two groups based on outcome. Long-term survivors (21 patients) and short-term survivors (24 patients) were defined using a double cut-off of 36 months for disease-free survival (DFS) and 60 months for overall survival (OS). Staining results for primary tumors and metastases were analyzed separately.Results. Mean follow-up period was 70 months. The mean values for DFS and OS were 109 and 125 months for long-term survivors and 3 and 25 months for short-term survivors. Staining for all four antigens was seen in the majority of cases (range = 72–96%) and tended to be comparable in primary tumors and their metastases. However, absence of immunoreactivity for STn was seen in 9/38 (24%) metastatic lesions and only 1/38 (3%) primary tumors. This finding did not reach statistical significance (P > 0.05). A combined pattern of membranous and cytoplasmic staining was predominant in the majority of cases. Enhanced staining for Ley and STn was detected in the invasive front of some tumors, while Slex and Tn immunoreactivity did not relate to cell location. Primary tumors and metastatic lesions of long-term survivors displayed immunoreactivity patterns that were comparable to those of short-term survivors. In the evaluation of survival curves, more diffuse staining for Slex showed marginal correlation with poor survival (P = 0.05), while a trend toward poorer survival was seen in tumors that were more extensively stained for Ley and Tn (P > 0.05).Conclusions. Ley, Slex, STn, and Tn antigens are widely expressed in primary ovarian carcinomas and their metastases. Altered expression of Sialyl Tn is observed with tumor progression in a fraction of ovarian carcinomas. Expression of membrane carbohydrate residues is prevalent in tumors of both long-term and short-term survivors and does not appear to be a strong predictor of disease outcome. However, larger studies are needed to further elucidate the role of these molecules in ovarian carcinogenesis.

Immunohistochemical Demonstration of Aberrant Glycosylation and Epidermal Growth Factor Receptor in Tubal Metaplasia of the Uterine Cervix

Tubal metaplasia (TM) of the uterine cervix may be confused with endocervical glandular dysplasia or adenocarcinoma of the uterine cervix in histologic specimens. TM is characterized histologically by architecturally normal endocervical glands containing ciliated or clear cells, nonciliated cells, and intercalated or peg cells, resembling normal tubal mucosa. Although several characteristics of TM are still undetermined, TM is considered a benign lesion. In this study, the expressions of epithelial-specific antigen (ESA), epidermal growth factor receptor (EGFR), and fucosyl SSEA1 (Ley) antigens were examined by an immunohistochemical method in 14 cases of TM in the uterine cervix (5 with normal endocervix, 5 with endocervical glandular dysplasia, 3 with adenocarcinomain situ,and 1 with microinvasive adenocarcinoma). In the normal endocervical cells, expression of the EGFR antigen was rarely observed in the cytoplasm, and ESA staining was generally restricted to the basolateral membrane. Leyexpression was occasionally observed in the cytoplasm of subcolumnar reserve cells. On the other hand, expression of EGFR, ESA, and Leywas observed in the cytoplasm of TM as well as in adenocarcinomas of the uterine cervix. These results suggest that TM in the uterine cervix might possess a neoplastic character.

Simultaneous Expression of Type 1 and Type 2 Lewis Blood Group Antigens by Helicobacter pyloriLipopolysaccharides: MOLECULAR MIMICRY BETWEEN H. PYLORILIPOPOLYSACCHARIDES AND HUMAN GASTRIC EPITHELIAL CELL SURFACE GLYCOFORMS

Previous structural investigations performed on the lipopolysaccharides (LPSs) from the human gastric pathogen Helicobacter pylori have revealed that these cell surface glycan molecules express type 2 partially fucosylated, glucosylated, or galactosylated N-acetyllactosamine O antigen chains (O-chains) of various lengths, which may or may not be terminated at the nonreducing end by Lewis X (Lex) and/or Ley blood group epitopes in mimicry of human cell surface glycoconjugates and glycolipids. Subsequently, serological experiments with commercially available Lewis-specific monoclonal antibodies also have recognized the presence of Lex and Ley blood group antigens in H. pylori but, in addition, have indicated the presence of type 1 chain Lea, Leb, and Led (H-type 1) blood group epitopes in some H. pylori strains. To confirm their presence, structural studies and additional serological experiments were undertaken on H. pylori strains suspected of carrying type 1 chain epitopes. These investigations revealed that the O-chain region of H. pylori strain UA948 carried both Lea (type 1) and Lex (type 2) blood group determinants. The O-chain from H. pylori UA955 LPS expressed the terminal Lewis disaccharide (type 1 chain) and Lex and Ley antigens (type 2). The O-chain of H. pylori J223 LPS carried the type 1 chain precursor Lec, the H-1 epitope (Led, type 1 chain) and an elongated nonfucosylated type 2 N-acetyllactosamine chain (i antigen). Thus, O-chains from H. pylori LPSs can also express fucosylated type 1 sequences, and the LPS from a single H. pylori strain may carry O-chains with type 1 and 2 Lewis blood groups simultaneously. That monoclonal antibodies putatively specific for the Leb determinant can detect glycan substructures (Le disaccharide, Lec, and Led) of Leb indicates their nonspecificity. The expression of both type 1 and 2 Lewis antigens by H. pylori LPSs mimics the cell surface glycomolecules present in both the gastric superficial (which expresses mainly type 1 determinants) and the superficial and glandular epithelium regions (both of which express predominantly type 2 determinants). Therefore, each H. pylori strain may have a different niche within the gastric mucosa, and each individual LPS blood group antigen may have a dissimilar role in H. pylori adaptation.

Typing of Helicobacter pylori with monoclonal antibodies against Lewis antigens in lipopolysaccharide.

Recently, it has been shown that the lipopolysaccharide (LPS) O antigen of Helicobacter pylori contains Lewis x (Lex), Lewis y (Ley), or both Lex and Ley antigens. We applied a serotyping method for H. pylori by an enzyme-linked immunosorbent assay with monoclonal antibodies (MAbs) specific for these antigens and the related fucosylated H type 1 (H1) antigen. The selected MAbs recognized the Lex and/or Ley structures in the LPS of H. pylori. The agreement between the results of biochemical compositional analysis and the serological data validated our serotyping system. A total of 152 strains from different geographic origins (The Netherlands, Canada, Poland, Italy, and People's Republic of China) were examined for typeability based on the presence of Lewis antigens. One hundred twenty-nine (84.9%) strains were typeable, and 12 different serotyping patterns were observed; 80.9% of the strains contained Lex and/or Le(y) antigens, and 18.4% reacted with the MAb against the related H1 antigen either alone or in combination with the Lex and/or Ley antigen. Our results show that the Lex and Ley antigens are frequently encountered in the LPS of H. pylori strains from various geographic origins. This typing method is an easy-to-perform technique, which can be used for strain differentiation in epidemiological studies of H. pylori infections.

Correlation between the number of apoptotic cells and expression of the apoptosis-related antigens Fas, Le(y) and bcl-2 protein in non-Hodgkin's lymphomas.

The relationship between the number of apoptotic cells and the expression of apoptosis-related antigens was examined in 56 cases of non-Hodgkin's lymphomas and in 10 cases of reactive hyperplastic lymph nodes (RHL). Apoptosis was visually quantified by the in situ end-labeling (ISEL) method, and the expression of Fas, Le(y) antigens and bcl-2 protein was examined by immunohistochemistry. The expression of Le(y) antigen was observed in germinal centers of RHL and 45% of non-Hodgkin's lymphomas. The apoptotic cell count (AC) in follicular lymphomas was significantly less than that in diffuse lymphomas. The distribution pattern of apoptotic cells in follicular lymphomas was inverse to that in RHL. In follicular lymphomas, AC was lower in follicles than in interfollicular areas. In contrast, AC was higher in follicles than in interfollicular areas in RHL. Le(y) antigen-positive lymphomas showed a significantly higher AC than the negative cases. The Fas antigen-positive lymphomas showed a higher AC than the negative cases. However, AC in bcl-2 protein-positive and negative cases was not significantly different. These results suggest that Ley and Fas antigens appear to be involved in the apoptotic tendency of tumor cells in non-Hodgkin's lymphomas, whereas bcl-2 does not necessarily.

Blood Group Antigen Expression on Vaginal Cells and Mucus in Women with and without A History of Urinary Tract Infections

Adherence of bacteria to carbohydrate receptors on the surface of vaginal epithelial cells is a critical event that precedes bacterial colonization of the vaginal mucosa and subsequent urinary tract infection. Blood group antigens, carbohydrate structures bound to lipids or proteins, constitute an important component of the uroepithelial cell membrane and may affect susceptibility to urinary tract infections. To determine if the ABH and Lewis antigen expression in women with a history of urinary tract infections differed from that of women without such a history, vaginal specimens from 87 women (42 patients and 45 controls) were analyzed for the detection of these antigenic determinants using monoclonal antibodies in quantitative immunoassays. The profile of ABH antigen expression was generally consistent with the ABO phenotype of the individual and appeared to be influenced by the secretor status. Secretors expressed higher levels of A, B and H determinants than nonsecretors. In addition, Lewis antigens were detected on vaginal cells and in mucus. Samples from nonsecretors expressed higher levels of Lea and Lex antigens, whereas secretors expressed higher levels of Leb and Ley antigens. The levels of antigen expression varied widely among individuals with the same blood type and secretor status. Comparisons between patient and control groups showed no significant differences in ABH or Lewis antigen expression overall, or when controlling for ABO or secretor phenotypes, respectively. These findings confirm our previous observations on healthy women, and document the heterogeneity of blood group antigen expression on vaginal epithelial cells and mucus from women with a history of urinary tract infections.

Effect of Lewis blood group antigen expression on bacterial adherence to COS-1 cells.

Epithelial cells from secretor individuals demonstrate decreased bacterial adherence compared with cells from nonsecretors. Lewis blood group antigen expression is one component of the secretor/nonsecretor phenotype and several epidemiologic studies have suggested a link between Lewis blood group antigen phenotype and susceptibility to urinary tract infections. In this study, we examined the possibility that the expression of the difucosylated Lewis blood group determinants, Leb and Ley (associated with the secretor phenotype), made cells less susceptible to Escherichia coli adherence by masking receptors for pili. COS-1 cells, which do not produce Lewis (Lea, Leb, Le(x), and Ley) blood group antigens, were used as target cells for bacterial adherence. The surface blood group antigen expression pattern of the cells was then modified by cotransfection with plasmids containing DNA inserts encoding alpha (1,2)-fucosyltransferase and alpha (1,3)- and alpha (1,4)-fucosyltransferases, resulting in the expression of Leb and Ley. E. coli HB101 expressing various adhesins (type 1, PapJ96, PapIA2, PapAD110, Prs, and S) from recombinant plasmids bound equally well to untransfected cells and transfected cells expressing Lea and Le(x) (nonsecretor phenotype) and Leb and Ley (secretor phenotype) antigens. We conclude that the presence of Leb and Ley antigens on cells from secretors does not alone mask receptors for E. coli pili or hinder bacterial adherence.