mAb Das-1 recognizes 3'-Sulfated Lewis A/C, which is aberrantly expressed during metaplastic and oncogenic transformation of several gastrointestinal Epithelia

INTRODUCTION

Multiple previous studies have shown the monoclonal antibody Das-1 (formerly called 7E12H12) is specifically reactive towards metaplastic and carcinomatous lesions in multiple organs of the gastrointestinal system (e.g. Barrett's esophagus, intestinal-type metaplasia of the stomach, gastric adenocarcinoma, high-grade pancreatic intraepithelial neoplasm, and pancreatic ductal adenocarcinoma) as well as in other organs (bladder and lung carcinomas). Beyond being a useful biomarker in tissue, mAb Das-1 has recently proven to be more accurate than current paradigms for identifying cysts harboring advanced neoplasia. Though this antibody has been used extensively for clinical, basic science, and translational applications for decades, its epitope has remained elusive.

METHODS

In this study, we chemically deglycosylated a standard source of antigen, which resulted in near complete loss of the signal as measured by western blot analysis. The epitope recognized by mAb Das-1 was determined by affinity to a comprehensive glycan array and validated by inhibition of a direct ELISA.

RESULTS

The epitope recognized by mAb Das-1 is 3'-Sulfo-Lewis A/C (3'-Sulfo-LeA/C). 3'-Sulfo-LeA/C is broadly reexpressed across numerous GI epithelia and elsewhere during metaplastic and carcinomatous transformation.

DISCUSSION

3'-Sulfo-LeA/C is a clinically important antigen that can be detected both intracellularly in tissue using immunohistochemistry and extracellularly in cyst fluid and serum by ELISA. The results open new avenues for tumorigenic risk stratification of various gastrointestinal lesions.

Lewis and ABO histo-blood types and the secretor status of patients hospitalized with COVID-19 implicate a role for ABO antibodies in susceptibility to infection with SARS-CoV-2

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) targets the respiratory and gastric epithelium, causing coronavirus disease 2019 (COVID-19). Tissue antigen expression variations influence host susceptibility to many infections. This study aimed to investigate the closely linked Lewis (FUT3) and ABO histo-blood types, including secretor (FUT2) status, to infections with SARS-CoV-2 and the corresponding severity of COVID-19.

STUDY DESIGN AND METHODS

Patients (Caucasians, n = 338) were genotyped for ABO, FUT3, and FUT2, and compared to a reference population of blood donors (n = 250,298). The association between blood types and severity of COVID-19 was addressed by dividing patients into four categories: hospitalized individuals in general wards, patients admitted to the intensive care unit with and without intubation, and deceased patients. Comorbidities were considered in subsequent analyses.

RESULTS

Patients with blood type Lewis (a-b-) or O were significantly less likely to be hospitalized (odds ratio [OR] 0.669, confidence interval [CI] 0.446-0.971, OR 0.710, CI 0.556-0.900, respectively), while type AB was significantly more prevalent in the patient cohort (OR 1.519, CI 1.014-2.203). The proportions of secretors/nonsecretors, and Lewis a+ or Lewis b+ types were consistent between patients and controls. The analyzed blood groups were not associated with the clinical outcome as defined.

DISCUSSION

Blood types Lewis (a-b-) and O were found to be protective factors, whereas the group AB is suggested to be a risk factor for COVID-19. The antigens investigated may not be prognostic for disease severity, but a role for ABO isoagglutinins in SARS-CoV-2 infections is strongly suggested.

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.

East-Asian Helicobacter pylori strains synthesize heptan-deficient lipopolysaccharide

The lipopolysaccharide O-antigen structure expressed by the European Helicobacter pylori model strain G27 encompasses a trisaccharide, an intervening glucan-heptan and distal Lewis antigens that promote immune escape. However, several gaps still remain in the corresponding biosynthetic pathway. Here, systematic mutagenesis of glycosyltransferase genes in G27 combined with lipopolysaccharide structural analysis, uncovered HP0102 as the trisaccharide fucosyltransferase, HP1283 as the heptan transferase, and HP1578 as the GlcNAc transferase that initiates the synthesis of Lewis antigens onto the heptan motif. Comparative genomic analysis of G27 lipopolysaccharide biosynthetic genes in strains of different ethnic origin revealed that East-Asian strains lack the HP1283/HP1578 genes but contain an additional copy of HP1105 and JHP0562. Further correlation of different lipopolysaccharide structures with corresponding gene contents led us to propose that the second copy of HP1105 and the JHP0562 may function as the GlcNAc and Gal transferase, respectively, to initiate synthesis of the Lewis antigen onto the Glc-Trio-Core in East-Asian strains lacking the HP1283/HP1578 genes. In view of the high gastric cancer rate in East Asia, the absence of the HP1283/HP1578 genes in East-Asian H. pylori strains warrants future studies addressing the role of the lipopolysaccharide heptan in pathogenesis.

Lewis(y) antigen-mediated positive feedback loop induces and promotes chemotherapeutic resistance in ovarian cancer

The present study aimed to investigate the association between Lewis(y) antigen and chemoresistance in ovarian cancer and to elucidate the underlying molecular mechanisms. Lewis(y) expression in chemoresistant ovarian cancer tissues and cells was detected by immunohistochemistry. α1,2‑fucosyltransferase (FUT1) expression in different ovarian cancer chemotherapy-resistant cells was analyzed by reverse transcription-quantitative PCR (RT-qPCR). Genes differentially expressed in the chemoresistant and sensitive groups were screened using a gene chip followed by validation using RT-qPCR and western blot analysis. We found that Lewis(y) and FUT1 expression in ovarian cancer cells was significantly increased following the induction of drug resistance. The positive expression rate and intensity of Lewis(y) in ovarian cancer chemoresistant tissues were also significantly higher than those in the sensitive group. Compared with the non-resistant cell lines, the differentially expressed genes were mainly enriched in the terms related to the transmembrane receptor protein tyrosine kinase signaling pathway and positive regulation of cell proliferation. Interaction network analysis predicted genes participating in the regulation of apoptotic processes. The highly differential expression of Annexin A4 (ANXA4), BCL2 interacting killer (BIK), transmembrane 4 L six family member 4 (TM4SF4) and pleckstrin homology-like domain family A member 1 (PHLDA1) was validated using RT-qPCR in ovarian cancer cell lines. Finally, ANXA4 expression was increased at both the mRNA and protein level in the drug‑resistant cells, and in addition, ANXA4 contained a Lewis(y) structure. The expression of Bcl-2 and other anti-apoptotic proteins increased with the increase of Lewis(y) expression. After blocking Lewis(y) using an antibody, the expression of the involved signaling pathway and apoptosis-related proteins decreased significantly. These findings provide strong evidence that Lewis(y) is a component of the structure of the ANXA4 membrane protein. Its overexpression can abnormally activate signaling pathways and regulate the expression of a number of factors, forming a positive feedback loop to induce the chemoresistance of ovarian cancer cells, and ultimately promoting the progression of ovarian cancer.

Development of a Surrogate Neutralization Assay for Norovirus Vaccine Evaluation at the Cellular Level

Noroviruses (NoVs) are the main pathogens responsible for sporadic and epidemic nonbacterial gastroenteritis, causing an estimated 219,000 deaths annually worldwide. There is no commercially available vaccine for NoVs, due partly to the difficulty in establishing NoV cell culture models. The histo-blood group antigen (HBGA) blocking assay is used extensively to assess the protective potential of candidate vaccine-elicited antibodies, but there is still no widely used cellular evaluation model. In this study, we have established a cell line-based NoV vaccine evaluation model through the construction of human α1,2-fucosyltransferase 2-overexpressing 293T (293T-FUT2) cell lines. The 293T-FUT2 cells stably expressed H type 2 and Lewis y antigens. Virus-like particles (VLPs) of the NoV prototype strain genogroup I.1 (GI.1) and the predominant strains GII.4 and GII.17 could attach to the cell line efficiently in a dose-dependent manner. Importantly, antisera against these NoV VLPs could inhibit the attachment of the VLPs, where the inhibitory effects measured by the attachment inhibition assay correlated significantly with the antibody levels determined by the HBGA blocking assay. Collectively, our attachment inhibition assay could serve as a surrogate neutralization assay for the evaluation of NoV vaccines at the cellular level.

Structural biology of antibody recognition of carbohydrate epitopes and potential uses for targeted cancer immunotherapies

Monoclonal antibodies represent the most successful class of biopharmaceuticals for the treatment of cancer. Mechanisms of action of therapeutic antibodies are very diverse and reflect their ability to engage in antibody-dependent effector mechanisms, internalize to deliver cytotoxic payloads, and display direct effects on cells by lysis or by modulating the biological pathways of their target antigens. Importantly, one of the universal changes in cancer is glycosylation and carbohydrate-binding antibodies can be produced to selectively recognize tumor cells over normal tissues. A promising group of cell surface antibody targets consists of carbohydrates presented as glycolipids or glycoproteins. In this review, we outline the basic principles of antibody-based targeting of carbohydrate antigens in cancer. We also present a detailed structural view of antibody recognition and the conformational properties of a series of related tissue-blood group (Lewis) carbohydrates that are being pursued as potential targets of cancer immunotherapy.

Crystal structures of GI.8 Boxer virus P dimers in complex with HBGAs, a novel evolutionary path selected by the Lewis epitope

Human noroviruses (huNoVs) recognize histo-blood group antigens (HBGAs) as attachment factors, in which genogroup (G) I and GII huNoVs use distinct binding interfaces. The genetic and evolutionary relationships of GII huNoVs under selection by the host HBGAs have been well elucidated via a number of structural studies; however, such relationships among GI NoVs remain less clear due to the fact that the structures of HBGA-binding interfaces of only three GI NoVs with similar binding profiles are known. In this study the crystal structures of the P dimers of a Lewis-binding strain, the GI.8 Boxer virus (BV) that does not bind the A and H antigens, in complex with the Lewis b (Le(b)) and Le(y) antigens, respectively, were determined and compared with those of the three previously known GI huNoVs, i.e. GI.1 Norwalk virus (NV), GI.2 FUV258 (FUV) and GI.7 TCH060 (TCH) that bind the A/H/Le antigens. The HBGA binding interface of BV is composed of a conserved central binding pocket (CBP) that interacts with the β-galactose of the precursor, and a well-developed Le epitope-binding site formed by five amino acids, including three consecutive residues from the long P-loop and one from the S-loop of the P1 subdomain, a feature that was not seen in the other GI NoVs. On the other hand, the H epitope/acetamido binding site observed in the other GI NoVs is greatly degenerated in BV. These data explain the evolutionary path of GI NoVs selected by the polymorphic human HBGAs. While the CBP is conserved, the regions surrounding the CBP are flexible, providing freedom for changes. The loss or degeneration of the H epitope/acetamido binding site and the reinforcement of the Le binding site of the GI.8 BV is a typical example of such change selected by the host Lewis epitope.

Defining the recognition elements of Lewis Y-reactive antibodies

Antibody response to carbohydrate antigens is often independent of T cells and the process of affinity/specificity improvement is considered strictly dependent on the germinal centers. Antibodies induced during a T cell-independent type 2 (TI-2) response are less variable and less functionally versatile than those induced with T cell help. The antigen specificity consequences of accumulation of somatic mutations in antibodies during TI-2 responses of Marginal Zone (MZ) B cells is a fact that still needs explanation. Germline genes that define carbohydrate-reactive antibodies are known to sculpt antibody-combining sites containing innate, key side-chain contacts that define the antigen recognition step. However, substitutions associated with MZ B cell derived antibodies might affect the mobility and polyspecificity of the antibody. To examine this hypothesis, we analyzed antibodies reactive with the neolactoseries antigen Lewis Y (LeY) to define the residue subset required for the reactive repertoire for the LeY antigen. Our molecular simulation studies of crystallographically determined and modeled antibody-LeY complexes suggests that the heavy-chain germline gene VH7183.a13.20 and the light-chain Vκ cr1 germline gene are sufficient to account for the recognition of the trisaccharide-H determinant Types 1–4, while the specificity for LeY is driven by the CDR3 backbone conformation of the heavy chain and not the side chain interactions. These results confirm that these monoclonals use germline-encoded amino acids to recognize simple carbohydrate determinants like trisaccharide-H but relies on somatic mutations in the periphery of the combining site to modify affinity for LeY through electrostatic interactions that leads to their optimized binding. These observations bring further attention to the role of mutations in T-cell independent antibodies to distinguish self from non-self carbohydrate antigens.

Is there any relationship between Le(b) antigen expression and Helicobacter pylori infection?

INTRODUCTION

Helicobacter pylori infection is one of the main causes of peptic ulcer. There are some blood groups acting as receptors for the pathogen. Based on this view and previous attempts, we tried to examine the relationship between Lewis blood group and H. pylori infection.

MATERIALS AND METHOD

Blood and saliva samples were collected from 60 patients with established peptic ulcer induced by H. pylori. Secretory status of each patient was determined by both direct agglutination and saliva tests.

RESULTS

Seventy-two percent of the patients were secretor and expressed Lewis B antigen. This rate in control group was 61%. Statistical analysis showed no significant difference between the two groups.

CONCLUSION

This study did not find any correlation between Le(b) antigen expression and presence of H. pylori-induced peptic ulcer. It is now recommended that other factors like Lewis(x) and sialyl Lewis(x) should be investigated in binding, colonization and virulence of H. pylori infection in the future.

High expression of Lewis y antigen and CD44 is correlated with resistance to chemotherapy in epithelial ovarian cancers

Objectives

To measure Lewis y antigen and CD44 antigen expression in epithelial ovarian carcinoma and to correlate the levels of these antigens with clinical response to chemotherapy.

Methods

The study cases included 34 cases of ovarian carcinoma with resistance to chemotherapeutic drugs, 6 partially drug-sensitive cases, and 52 drug-sensitive cases (92 total).

Results

The rates of expression of Lewis y antigen and CD44 antigen were significantly greater in the drug-resistant group than that in the partially-sensitive or sensitive groups. Surgical stage, residual tumor size and expression of CD44 and Lewis y antigen in ovarian carcinoma tissues were independent risk factors for chemotherapeutic drug resistance.

Conclusions

Over-expression of Lewis y and CD44 antigen are strong risk factors for chemotherapeutic drug resistance in ovarian carcinoma patients.

Glycan array analysis of the antigen repertoire targeted by tumor-binding antibodies

Immunization with whole cells has been used extensively to generate monoclonal antibodies, produce protective immune responses, and discover new disease antigens. While glycans are abundant on cell surfaces, anti-glycan immune responses have not been well-characterized. We used glycan microarrays to profile 49 tumor-binding monoclonal antibodies generated by immunizing mice with whole cancer cells. A substantial proportion (41%) of the tumor binding antibodies bound carbohydrate antigens. The antibodies primarily recognize a group of 5 glycan antigens: Sialyl Lewis A (SLeA), Lewis A (LeA), Lewis X (LeX), blood group A (BG-A), and blood group H on a type 2 chain (BG-H2). The results have important implications for monoclonal antibody production and cancer vaccine development.

Use of real-time, label-free analysis in revealing low-affinity binding to blood group antigens by Helicobacter pylori

Infectious diseases are often initiated by microbial adherence that is mediated by the binding of attachment molecules, termed adhesins, to cell surface receptors on host cells. We present an experimental system, oblique-incidence reflectivity difference (OI-RD) microscopy, which allows the detection of novel, low-affinity microbial attachment mechanisms that may be essential for infectious processes. OI-RD microscopy was used to analyze direct binding of the oncopathogen, Helicobacter pylori ( H. pylori ) to immobilized glycoconjugates in real time with no need for labeling tags. The results suggest the presence of additional Lewis b blood group antigen (Le(b)) binding adhesins that have not been detected previously. OI-RD microscopy also confirmed the high-affinity binding of H. pylori outer-membrane protein BabA to Le(b). The OI-RD microscopy method is broadly applicable to real-time characterization of intact microbial binding to host receptors and offers new strategies to elucidate the molecular interactions of infectious agents with human host cells.

Effects of Lewis Y antigen on the gene expression of multiple drug resistance-associated proteins in human ovarian cancer RMG-I-H cells

The effects of Lewis Y antigen on the gene expression of multiple drug resistance-associated proteins in human ovarian cancer RMG-I-H cells were unclear by now. In this study, we detected the gene expression of multiple drug resistance-associated proteins (MRP) in RMG-I-H cells and RMG-I-H cells treated with anti-Lewis Y monoclonal antibody to investigate the association between Lewis Y antigen and the gene expression of drug resistance-associated proteins. Compared with RMG-I cells, the expression of MRP1, MRP2, protein kinase C-alpha (PKC-alpha), and topoisomerase I (Topo I) mRNAs in RMG-I-H cells were significantly upregulated, while the MDR-1 mRNA was downregulated. Immunochemistry analyses indicated that the in vitro and in vivo expression levels of MDR-1 protein (P-gp) in RMG-I-H cells were significantly higher than those in RMG-I cells. After RMG-I-H cells were treated with anti-Lewis Y monoclonal antibody, the expression levels of MDR-1, MRP1, MRP2, PKC-alpha, and Topo I mRNAs gradually decreased with the prolongation of treatment duration. In contrast, no obvious changes were noted in the expression levels of these mRNAs in the non-treatment group. At 6 h after treatment, the relative levels of MDR-1, MRP1, MRP2, PKC-alpha, and Topo I mRNAs in the antibody treatment group were significantly lower than those in the non-treatment group. In conclusion, Lewis Y antigen is closely associated with regulating the gene expression of multiple drug resistance-associated proteins.

The role of endotoxin in infection: Helicobacter pylori and Campylobacter jejuni

Both Helicobacter pylori and Campylobacter jejuni are highly prevalent Gram-negative microaerophilic bacteria which are gastrointestinal pathogens of humans; H. pylori colonizes the gastroduodenal compartment and C. jejuni the intestinal mucosa. Although H. pylori causes chronic gastric infection leading to gastritis, peptic ulcers and eventually gastric cancer while C. jejuni causes acute infection inducing diarrhoeal disease, the endotoxin molecules of both bacterial species contrastingly contribute to their pathogenesis and the autoimmune sequelae each induces. Compared with enterobacterial endotoxin, that of H. pylori has significantly lower endotoxic and immuno-activities, the molecular basis for which is the underphosphorylation and underacylation of the lipid A component that interacts with immune receptors. This induction of low immunological responsiveness by endotoxin may aid the prolongation of H. pylori infection and therefore infection chronicity. On the other hand, this contrasts with acute infection-causing C. jejuni where overt inflammation contributes to pathology and diarrhoea production, and whose endotoxin is immunologically and endotoxically active. Futhermore, both H. pylori and C. jejuni exhibit molecular mimicry in the saccharide components of their endotoxins which can induce autoreactive antibodies; H. pylori expresses mimicry of Lewis and some ABO blood group antigens, C. jejuni mimicry of gangliosides. The former has been implicated in influencing the development of inflammation and gastric atrophy (a precursor of gastic cancer), the latter is central to the development of the neurological disorder Guillain-Barré syndrome. Both diseases raise important questions concerning infection-induced autoimmunity awaiting to be addressed.

[Helicobacter pylori infection and autoimmune disease such as immune thrombocytopenic purpura]

Helicobacter pylori infection is implicated in the pathogenesis of extradigestive diseases such as acne rosacea and idiopathic chronic urticaria and autoimmune diseases such as autoimmune gastric atrophy, rheumatoid arthritis, anti phospholipid antibody syndrome, autoimmune thyroiditis, Sjoegren syndrome, Henoch-Schoenlein purpura, and Type B insulin resistance syndrome. H. pylori eradication ameliorated the condition in some, but not all, of those with these autoimmune diseases. Recent studies primarily in Italy and Japan found that H. pylori eradication in those infected with chronic immune thrombocytopenic purpura (ITP) results in a persistent platelet count increase in over half of those treated, suggesting that although pathogenetic mechanisms underlying the relationship between H. pylori infection and autoimmune disease remain unclear, yet-unknown immunological events induced by H. pylori infection almost certainly occur in the development of autoimmune response. A majority of isolated H. pylori strains express human Lewis (Le(x) and/or Le(y) determinants and in some strains, Le(a), Le(b), sialyl-Le(x)), and H determinants in the O-chain of the surface lipopolysaccharide. Previous studies showed that this molecular mimicry helps the bacterium evade host responses while evoking autoantibody responses to Le antigens. The anti-Le(y) autoantibody is also reported to promote H. pylori adhesion to gastric epithelial cells, leading to development of gastric atrophy. Moreover, one can hypothesize that anti-Le autoreactive antibodies induced by H. pylori infection are involved in the development of autoimmune diseases, although no clinical studies showing that anti-Le immune responses are involved in the etiology of these autoimmune diseases have been conducted. Proving this hypothesis would require quantitative and qualitative analysis of autoantibodies and T cell functions to Le antigens. High frequent phase variation of Le structures in the O-polysaccharide of H. pylori may influence the immune response of patients to Le antigens.

Phase I biodistribution and pharmacokinetic study of Lewis Y-targeting immunoconjugate CMD-193 in patients with advanced epithelial cancers

PURPOSE

This phase I study explored the biodistribution and pharmacokinetics of the immunoconjugate CMD-193 [a humanized anti-Lewis Y (Le(y)) antibody conjugated with calicheamicin in patients with advanced cancers expressing the Le(y) antigen.

EXPERIMENTAL DESIGN

The primary objectives were to determine biodistribution and pharmacokinetics of CMD-193. Secondary objectives included response rates and change in tumor metabolism. Patients with progressive, measurable, and Le(y) positive malignancies were eligible for enrollment in one of two dose cohorts, 1.0 and 2.6 mg/m(2). The first cycle was trace labeled with (111)In for biodistribution assessment using gamma camera imaging. Subsequent cycles were administered every 3 weeks up to a maximum of six cycles, depending on toxicity and response. Pharmacokinetic analysis was based on radioassay and ELISA.

RESULTS

Nine patients were enrolled in the study. Biodistribution images showed initial blood pool activity, followed by markedly increased hepatic uptake by day 2, and fast blood clearance in all patients. There was low uptake in tumor in all patients. The overall T(1/2)beta of (111)In-CMD-193 was 102.88 +/- 35.67 hours, with no statistically significant difference between the two dose levels. One patient had a partial metabolic response on (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG PET) after four cycles, but no radiological responses were observed. Myelosuppression and effects on liver function were the most significant adverse effects.

CONCLUSIONS

CMD-193 shows rapid blood clearance and increased hepatic uptake compared with prior studies of the parental antibody hu3S193. These results highlight the importance of biodistribution and pharmacodynamic assessment in early phase studies of new biologics to assist in clinical development.

Anti-carbohydrate antibodies of normal sera: findings, surprises and challenges

We have used microchip format glycan array to characterize the individual carbohydrate recognition patterns by antibodies (Ab) in sera of 106 healthy donors. The glycan library included blood group antigens and other most frequent terminal oligosaccharides and their cores of mammalian N- and O-linked glycoproteins and glycolipids, tumor-associated carbohydrate antigens, and common components of bacterial/pathogenic polysaccharides and lipopolysaccharides, totally 205 glycans. The serum Ab interacted with at least 50 normal human glyco-motifs. Apart from expected blood group-, xeno- (heterophil) and infection-related binding activities, we observed a number of new and unexpected features. The surprising, relatively high antibody binding was found to the blood group P(1) and P(k) trisaccharides and H(type 2) trisaccharide. Novel and very high binding activities have been observed towards Galbeta1-3GlcNAc (Le(C)) related glycans, especially 3'-O-Su-Le(C), and towards 4'-O-sulfated lactosamine. Relatively high and uniform Ab binding to GalNAcalpha1-3Gal disaccharide demonstrated absence of correlation with fucosylated blood group A GalNAcalpha1-3(Fucalpha1-2)Gal antigen-similarly to well known relationship between Galalpha1-3Gal and true, fucosylated blood group B Galalpha1-3(Fucalpha1-2)Gal antigen. The binding intensity to Galalpha1-3Galbeta1-4GlcNAc xenoantigen was shown to be rather modest. Absence or very low Ab binding was found against oligosialic acid, sialooligosaccharides except SiaT(n), type 2 backbone glycans such as Le(y), and biantennary N-chain as well as its truncated forms, i.e. without terminal Sia, SiaGal, and SiaGalGlcNAc motifs. We have also found that Ab are capable of recognizing the short inner core typical for glycolipids (-Galbeta1-4Glc) and glycoproteins (-GalNAcalpha) as a fragment of bigger glycans.

[Detection of ABH-Lewis antigens in trace discharges using one-stage immunoenzyme assay with dot modification]

A one-step modification ofimmunoenzyme assay (dot variant) is proposed for the detection of ABH-Lewis antigens in human discharges (saliva, sperm, vaginal discharge). Sensitivity and specificity of the new method is higher than those of other methods currently used in forensic medicine for the detection of antigens in human body discharges; its other advantages over routine techniques include procedural simplicity, high performance, and the possibility of conducting series measurements with minimal labour inputs. Moreover, it provides information not only about group characteristic but also about category of discharge. The analysis is carried out in supernatant fractions which permits to reserve cellular material for molecular-genetic studies.

Expression of sialyl Lex, sialyl Lea, Lex and Ley glycotopes in secreted human ovarian cyst glycoproteins

Human blood group A, B, H, Ii, Le(a) and Le(b) antigens and their determinants expressed on ovarian cyst glycoproteins have been studied for over five decades. However, little is known about sialyl Le(x) and sialyl Le(a) glycotopes, which play essential roles in normal immunity, inflammation, and cancer cell metastasis. Furthermore, Le(x) and Le(y) were classified as glycotopes of unknown genes. Identification of these Lewis epitopes was hampered by the lack of specific antibodies. In this study, the occurrence of sialyl Le(x), sialyl Le(a), Le(x) and Le(y) reactivities in cyst glycoproteins was characterized by enzyme-linked immunosorbent assays. The results indicated that most human ovarian cyst glycoproteins carried Le(x) (8/25) and/or Le(y) (17/25) glycotopes. The expression (epitopes) of the new genes described in previous reports are Le(x) and Le(y) glycotopes; the reactivities of sialyl Le(x) and sialyl Le(a) glycotopes in secreted cyst glycoproteins may be affected by the conditions of purification; the relationship between Le(y) and human blood group ABH was confirmed; recognition profiles of sialyl Le(x), sialyl Le(a), Le(x) and Le(y) present in the carbohydrate chains of water-soluble cyst glycoproteins were illustrated; possible attachments of glycotopes to the internal carbohydrate complex of cyst glycoproteins have been reconstructed; proposed biosynthetic pathways for the formation of sialyl Le(a), sialyl Le(x), Le(x), Le(y), ALe(y) and BLe(y) determinant structures on Type I and Type II core structures of human ovarian cyst glycoproteins are also included in this study.

[Identification of the hemolytic transfusion reaction caused by lewis antibody using serological and molecular biological methods]

To analyse the reason for one case of hemolytic transfusion reaction, antibodies in a patient's serum were identified using panel cells and Le (a-b-) phenotype cells, patient phenotype was identified by using anti-Le(a) and anti-Le(b) blood grouping reagents and the entire coding region of FUT3 gene was amplified by PCR and sequenced directly. The results showed that both IgM anti-Le(a) and anti-Le(b) antibodies were detected in patient's serum. Red cells was typed as Le (a-b-) phenotype and the FUT3 genotype was homozygote for non-functional le(59, 508) alleles. In conclusion, anti-Le(b) antibody can result in hemolytic transfusion reaction, FUT3 gene is homozygous for le(59, 508) allele resulting in Le (a-b-) phenotype.

Disulfide bond bridged divalent antibody-toxin, (Fab-PE38fl)2, with the toxin PE38 fused to the light chain

B3 antibody specifically binds the LewisY-related carbohydrate antigen of many carcinomas, and it is used as a model antibody in this study. In a previous study, the Fab fragment of the antibody was fused to a 38 kDa truncated form of Pseudomonas exotoxin A, PE38, to make Fab- PE38, where PE38 is fused to the Fd fragment of the Fab domain. This parent monomer molecule, Fab-PE38, had no cysteine in the hinge region, and it could not make a disulfide bond to form a disulfide bond bridged homodimer. In this study, we constructed three different kinds of divalent Fab-toxin fusion homodimers where the toxin is fused to the light chain of Fab, (Fab-PE38fl)2. In addition to the PE38 toxin fused to the light chain, these three molecules have different hinge sequences h1, h2, and h3 making Fabh1-, Fabh2-, and Fabh3-PE38fl monomers, respectively. These hinges contain only one cysteine on different positions of the hinge sequence. The disulfide bond between the hinge region of two monomers forms homodimers (Fabh1-PE38fl)2, (Fabh2-PE38fl)2, and (Fabh3- PE38fl)2. The refolding yields of these dimers were 5- 16-fold higher than a previously constructed dimer where the PE38 was fused to the Fd fragment (Fabh1-PE38)2. Our data suggest that the steric repulsion between the two PE38s in (Fabh1-PE38)2 during disulfide bridge formation is relieved by fusing it at the end of the light chain. The best cytotoxicity value of these dimers showed about 2.5-fold higher on an MCF7 cell line than that of the monovalent reference molecule in ng/ml scale, which is 15-fold higher in pM scale.

Tumor targeting by a multivalent single-chain Fv (scFv) anti-Lewis Y antibody construct

The use of single-chain variable fragment (scFv) constructs has been investigated in cancer radioimmunotherapy (RIT) and radioimmunodetection, as these molecules permit rapid tumor penetration and clearance from the serum relative to whole IgG. Multimerization of scFv constructs has demonstrated improvements in functional affinity (i.e., avidity) and maximal tumor uptake. In this paper, we report the first biodistribution and pharmacokinetics studies of a noncovalent, direct-linked scFv (V(L)-0-V(H)) trimeric/tetrameric "multimer" of the anti-Lewis Y monoclonal antibody, hu3S193. The in vitro binding and in vivo biodistribution of the hu3S193 multimer was characterized alongside the hu3S193 F(ab')(2) following radiolabeling with the Indium-111 ((111)In) radioisotope. Immunoreactivities of the radiolabeled multimer and F(ab')(2) were 73% and 53.2%, and binding affinities (K(a)) were 1.58 x 10(7) M(1) and 4.31 x 10(6) M (1) for the multimer and F(ab')(2), respectively. Maximal tumor uptake in Le(y)-positive MCF-7 breast cancer xenografted BALB/c nude mice was 12.6 +/- 2.5 percent injected dose/per gram (%ID/g) at 6 hours postinjection for the multimer and 15.7 +/- 2.1 %ID/g at 24 hours postinjection for the F(ab')(2). However, limited in vitro stability and high renal localization of radiolabeled constructs were observed, which, despite the observed tumor targeting of the hu3S193 multimer, most likely preclude its use in RIT and imaging modalities.

Role of ABO secretor status in mucosal innate immunity and H. pylori infection

The fucosylated ABH antigens, which constitute the molecular basis for the ABO blood group system, are also expressed in salivary secretions and gastrointestinal epithelia in individuals of positive secretor status; however, the biological function of the ABO blood group system is unknown. Gastric mucosa biopsies of 41 Rhesus monkeys originating from Southern Asia were analyzed by immunohistochemistry. A majority of these animals were found to be of blood group B and weak-secretor phenotype (i.e., expressing both Lewis a and Lewis b antigens), which are also common in South Asian human populations. A selected group of ten monkeys was inoculated with Helicobacter pylori and studied for changes in gastric mucosal glycosylation during a 10-month period. We observed a loss in mucosal fucosylation and concurrent induction and time-dependent dynamics in gastric mucosal sialylation (carbohydrate marker of inflammation), which affect H. pylori adhesion targets and thus modulate host–bacterial interactions. Of particular relevance, gastric mucosal density of H. pylori, gastritis, and sialylation were all higher in secretor individuals compared to weak-secretors, the latter being apparently “protected.” These results demonstrate that the secretor status plays an intrinsic role in resistance to H. pylori infection and suggest that the fucosylated secretor ABH antigens constitute interactive members of the human and primate mucosal innate immune system.

The common ABO blood group antigen system was described in the early 20th century. In addition, it has been known for 60 years that the majority of individuals also express the corresponding ABO antigens (carbohydrate identity tags) in their saliva, tears, milk, and mucus secretions in the digestive tract. To this date, however, the biological function of the ABO blood group antigens has remained an enigma. Here, we show that the great majority of Rhesus monkeys are of blood group B and weak-secretors, i.e., are similar to the human populations in South Asia from where these monkeys originate. This observation suggests that an evolutionary adaptation in digestive tract mucosal carbohydrate patterns to local environmental selection has occurred. In addition, we demonstrate that long-term infection by the “peptic ulcer bacterium” Helicobacter pylori induces mucosal carbohydrate patterns that change according to the individual secretor phenotype. The common weak-secretor monkeys were apparently “protected,” as they had stable glycosylation, lower inflammation, and lower bacterial infection load, whereas the less common secretor animals had increased levels of inflammation-associated mucosal carbohydrate patterns and a transient decrease in the ABO blood group system type of carbohydrates. These novel observations suggest that the individual ABO blood group and secretor phenotype are part of human and non-human primate innate immunity against infectious disease.

DC-SIGN mediates adhesion and rolling of dendritic cells on primary human umbilical vein endothelial cells through LewisY antigen expressed on ICAM-2

Immature dendritic cells (DCs) are recruited from blood into tissues to patrol for foreign antigens. After antigen uptake and processing, DCs mature and migrate to the secondary lymphoid organs where they initiate immune responses. DC-SIGN is a DC-specific C-type lectin that acts both as a pattern recognition receptor and as an adhesion molecule. As an adhesion molecule, DC-SIGN is able to mediate rolling and adhesion over endothelial cells under shear flow. In this study, we show that the binding partner of DC-SIGN on endothelial cells is the glycan epitope Lewis(Y) (Le(Y)), expressed on ICAM-2. The interaction between DC-SIGN on dendritic cells and ICAM-2 on endothelial cells is strictly glycan-specific. ICAM-2 expressed on CHO cells only served as a ligand for DC-SIGN when properly glycosylated, underscoring its function as a scaffolding protein. The expression of Le(Y) in endothelial cells is directed by the enzyme FUT1. Silencing of FUT1 results in a decrease in the rolling and adhesion of immature DCs over endothelial cells. The identification of Le(Y) as the carbohydrate ligand of DC-SIGN in endothelial cells opens new possibilities for the manipulation of DC migration.

[Inhibitory effect of anti-Lewis y antibody on alpha1,2-fucosyltransferase gene transfected human ovarian cancer cells in vitro]

AIM

To study the inhibitory effect of anti-Lewis y monoclonal antibody on proliferation, adhesion and invasion of alpha1, 2-fucosyltransferase gene transfected human ovarian cancer cell line RMG-I-H with over-expression of Lewis y antigen in vitro.

METHODS

The changes of proliferation, adhesion and invasion of RMG-I-H cells in vitro were detected by cell growth assay, cell adhesive assay and cell invasive assay, respectively, with goat anti-human IgG antibody treated group or non-antibody treated group as control.

RESULTS

The proliferation and adhesion of RMG-I-H cells were remarkably inhibited by preincubation of the tumor cells with anti-Lewis y antibody in vitro (P<0.05). The growth inhibitory rate from the second day to the seventh day was 5.62%, 19.75%, 34.96%, 46.51%, 49.78% and 33.33%, respectively. The adhesion inhibitory rate at different time points (15, 30, 60 min) was 47.59%, 58.64% and 13.85%, respectively. Invasive assay with a transwell cell culture chamber showed that there were no significant differences of invasion in vitro between each concentration of the Lewis y antibody treated group and non-antibody treated group (P>0.05).

CONCLUSION

Anti-Lewis y antibody significantly inhibits the proliferation and adhesion of RMG-I-H cells cultured in vitro, but it has no effect on invasion, which indicates that Lewis y is associated with some biological behaviors, such as proliferation and adhesion. The antibody against Lewis y may be an effective anti-metastasis agent for the treatment of patients with ovarian cancer.

Anti-Lewis alloimmunization: report of seven cases

OBJECTIVE

The purpose of this study was to investigate the perinatal results of seven pregnant women with anti-Lewis antibodies and evaluate the need to screen for these antigens during routine prenatal care.

SETTING

São Paulo Universtity Hospital, São Paulo, Brazil.

POPULATION

200 Rh-negative pregnant women with a positive indirect Coombs test, managed during a 6-year period.

METHODS

The charts of all patients were reviewed to collect pertinent data and the variables were analyzed.

MAIN OUTCOME MEASURES

Indirect Coombs test titer, intrauterine transfusion, mode of delivery, gestational age at birth, birthweight, neonatal transfusion, duration of neonatal hospitalization and perinatal mortality.

RESULTS

All newborn infants were classified as adequate for gestational age at birth and none needed intrauterine or neonatal transfusions. All infants, except one, were discharged in good health on the third day after birth.

CONCLUSIONS

Alloimmunized pregnancies (Levis antigens) have good perinatal results.

Radioimmunotherapy with alpha-particle emitting 213Bi-C-functionalized trans-cyclohexyl-diethylenetriaminepentaacetic acid-humanized 3S193 is enhanced by combination with paclitaxel chemotherapy

PURPOSE

Previous experience in solid tumor radioimmunotherapy studies has indicated that greatest therapeutic efficacy is achieved in the treatment of small-volume disease. alpha-Particle-emitting radioisotopes possess several physical characteristics ideally suited to the treatment of minimal residual disease. Therefore, we have investigated the efficacy of the alpha-particle-emitting bismuth-213 (213Bi) radioimmunotherapy using the humanized anti-Lewis Y (Ley) monoclonal antibody humanized 3S193 (hu3S193).

EXPERIMENTAL DESIGN

The intracellular localization of hu3S193 in Ley-positive MCF-7 breast carcinoma cells was assessed by confocal microscopy. Cytotoxicity of 213Bi-hu3S193 and apoptosis was assessed using [3H]thymidine incorporation assay and ELISA, respectively. Immunoblotting for gamma-H2AX assessed DNA strand breaks. In vivo efficacy of 213Bi-hu3S193 was assessed using a minimal residual disease model in BALB/c nude mice, with radioconjugate [15, 30, and 60 microCi (9.2 microg)] injected 2 days after s.c. implantation of MCF-7 cells. Radioimmunotherapy was also combined with a single injection of 300 microg paclitaxel to explore improved efficacy. Further, mice with established tumors received 30, 60, or 120 microCi (14.5 microg) of 213Bi-hu3S193 to assess the effect of tumor volume on treatment efficacy.

RESULTS

hu3S193 is internalized via an endosomal and lysosomal trafficking pathway. Treatment with 213Bi-hu3S193 results in >90% cytotoxicity in vitro and induces apoptosis and increased gamma-H2AX expression. 213Bi-hu3S193 causes specific and significant retardation of tumor growth even in established tumors, and efficacy was enhanced by paclitaxel to produce defined complete responses.

CONCLUSIONS

These studies show the potency of alpha-particle radioimmunotherapy and warrant its further exploration in the treatment of micrometastatic disease in Ley-positive malignancies.

Expression of bisecting type and Lewisx/Lewisy terminated N-glycans on human sperm

Human sperm lack major histocompatibility class I molecules, making them susceptible to lysis by natural killer (NK) cells. Major histocompatibility class I negative tumor cells block NK cell lysis by expressing sufficient amounts of bisecting type N-glycans on their surfaces. Therefore, sperm could employ the same strategy to evade NK cell lysis. The total N-glycans derived from sperm were sequenced using ultrasensitive mass spectrometric and conventional approaches. Three major classes of N-glycans were detected, (i) high mannose, (ii) biantennary bisecting type, and (iii) biantennary, triantennary, and tetraantennary oligosaccharides terminated with Lewisx and Lewisy sequences. Immunostaining of normal sperm showed that glycoproteins bearing Lewisy sequences are localized to the acrosome and not the plasma membrane. In contrast, defective sperm showed distinct surface labeling with anti-Lewisy antibody. The substantial expression of high mannose and complex type N-glycans terminated with Lewisx and Lewisy sequences suggests that sperm glycoproteins are highly decorated with ligands for DC-SIGN. Based on previous studies, the addition of such carbohydrate signals should inhibit antigen-specific responses directed against sperm glycoproteins in both the male and female reproductive systems. Thus, the major N-glycans of human sperm are associated with the inhibition of both innate and adaptive immune responses. These results provide more support for the eutherian fetoembryonic defense system hypothesis that links the expression of carbohydrate functional groups to the protection of gametes and the developing human in utero. This study also highlights the usefulness of glycomic profiling for revealing potential physiological functions of glycans expressed in specific cell types.

Analysis of lysine clipping of a humanized Lewis-Y specific IgG antibody and its relation to Fc-mediated effector function

During the analytical characterization of the humanized Lewis-Y specific monoclonal antibody IGN311 (IgG1/kappa) used for passive anti-cancer therapy in humans, isoelectric focusing (IEF) experiments revealed that IGN311 batches produced in serum-containing and serum-free medium, respectively, displayed different banding patterns. The additional bands in the IEF pattern correlated with additional peaks observed by subsequent cation exchange (CEX)-HPLC analysis. Since the IEF pattern is one of the specification criteria in the quality control of monoclonal antibodies and a non-matching pattern may be indicative for lot-to-lot inconsistency, this phenomenon was investigated in detail. First, we investigated whether a difference in antibody glycosylation was the cause for the observed charge heterogeneity. De-N-glycosylation experiments demonstrated that charge heterogeneity observed in the IEF pattern is not a consequence of glycosylation. In contrast, sample treatment by carboxypeptidase B, removing the carboxy-terminal lysine residues from the two heavy chains of the antibody, resulted in reduced charge heterogeneity eliminating the two most basic bands observed in IEF. These data were supported by reversed phase HPLC-MALDI-TOF-MS analysis of enzymatically cleaved peptides of the antibody as well as by carboxy-terminal sequencing of the heavy chains. It was demonstrated that the differences in the IEF banding pattern were due to lysine clipping occurring during the production of the antibody. The antibody batch produced under serum-free conditions was less affected by lysine clipping. Both antibody variants--clipped and unclipped--elicited the same potency in a complement dependent cytotoxicity (CDC) assay demonstrating that lysine clipping of IGN311 does not impair Fc-mediated effector functions.

High-throughput carbohydrate microarray profiling of 27 antibodies demonstrates widespread specificity problems

Progress toward understanding the biological roles of carbohydrates has been remarkably slow, and efforts to exploit this class of biopolymers as diagnostic and therapeutic targets have proven extremely challenging. Both basic and clinical research rely heavily on identifying and monitoring expression levels of carbohydrates. Over the last 30 years, the majority of expression information has been derived from antibody- and lectin-binding studies. Using a carbohydrate microarray containing 80 different glycans and glycoproteins, the specificities of 27 antiglycan antibodies were evaluated, including antibodies to histo-blood group A, B, and H antigens (81FR2.2, CLCP-19B, B389, 92FR-A2, B480, B460, B376, and B393), Lewis antigens (7LE, 15C02, 28, ZC-18C, 121SLE, CA199.02, PR.5C5, 2-25LE, BR55, T174, T218, F3, A70-C/C8, FR4A5, and K21), and other tumor-associated antigens (B389, 1A4, B1.1, and 5B5). In total, evaluation of over 2000 individual carbohydrate-protein interactions was carried out. More than half of the antibodies considered to be specific for their designated antigen were found to cross-react with other glycans. The cross-reactive glycans could be mistaken for the designated antigen in biopsy samples or other biological samples, leading to inaccurate conclusions.

Synthetic glycolipid modification of red blood cell membranes

BACKGROUND

Glycolipids have a natural ability to insert into red cell (RBC) membranes. Based on this concept the serology of RBCs modified with synthetic analogs of blood group glycolipids (KODE technology) was developed, which entails making synthetic glycolipid constructs engineered to have specific performance criteria. Such synthetic constructs can be made to express a potentially unlimited range of carbohydrate blood group determinants.

STUDY DESIGN AND METHODS

Synthetic constructs incorporating A, B, acquired-B, and Le(a) blood group determinants were constructed and used to modify RBCs. Modified cells were assessed by routine serologic methods using a range of commercially available monoclonal antibodies.

RESULTS

RBCs modified with different concentrations of synthetic glycolipids were able to give controllable serologic results. Synthetic A and B modified cells were able to be created to represent the serology of "weak" subgroups. Specialized cells such as those bearing synthetic acquired-B antigen reacted as expected, but also exhibited extended features due to the cells bearing only specific antigen. Synthetic Le(a)-modified cells reacted as expected with anti-Le(a) reagents, but unexpectedly, were also able to detect the chemical anti-Le(ab) specificity of serologic monoclonal anti-Le(b) reagents.

CONCLUSION

RBCs can be created to express normal and novel carbohydrate profiles by inserting synthetic glycolipids into them. Such cells will be useful in creating specialized antigen panels and for quality control purposes.

A Monoclonal Antibody to Lewis Y/Lewis b Revealing Mimicry of the Histone H1 to Carbohydrate Structures

Antibodies to either peptide or carbohydrate tumour antigens are established tools for diagnostics and therapy. We here describe an antibody (A70-A/A9) recognizing a carbohydrate epitope common to the tumour-associated Lewis Y and Lewis b antigens (Fucalpha1-2Galbeta1-4/3[Fucalpha1-3/4]GlcNAcbeta-). Its specificity was established without doubt with a panel of 86 synthetic mono- and oligosaccharidic structures. This antibody was found to cross-react with the nuclear protein histone H1. Binding to H1 was specific, periodate-insensitive (non-carbohydrate) and saturable. Histone H1 was able to inhibit Lewis Y binding very effectively in a concentration-dependent manner. We conclude that it represents an example of natural peptide mimicry of a carbohydrate epitope. It may explain the observed occurrence of 'anti-histone autoantibodies' in cancer patients.

Antigen coupled with Lewis-x trisaccharides elicits potent immune responses in mice

BACKGROUND

Glycoproteins containing Lewis-x (Le(x)) trisaccharides are often associated with the host's adaptive T(H)2-type immunity, but the mechanisms underlying the T(H)2-biased response are at present unclear.

OBJECTIVE

The modulatory effect of Le(x) or its glycoconjugates on IgE/T(H)2 responses was investigated.

METHODS

The levels of serum antibodies and cytokines were analyzed by means of ELISA, RT-PCR, or both.

RESULTS

In C3H mice Le(x) coupled with BSA (Le(x)-BSA) elicited higher levels of specific IgE and IgG1, but not IgG2a, which were associated with increased levels of splenic T(H)2 cytokines when compared with those seen in BSA-sensitized mice. In BALB/c mice sensitized with Le(x)-BSA or Le(x) mixed with ovalbumin, significantly increased levels of specific IgE and IgG2a antibodies were found concomitant with reduced levels of serum IL-12p70. These effects were attenuated in IL-12-deficient BALB/c mice. Le(x) and an isomer, Le(y), but not other isomers, inhibited the production of LPS-induced IL-12p70, associated with a significant reduction of nuclear NF-kappaB, in bone marrow-derived dendritic cells from BALB/c mice, suggesting that Le(x)-induced suppression of IL-12p70 results in an enhanced T(H)2 response. The addition of mannan, a known ligand for dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin, abrogated the suppressive effect of Le(x) trisaccharides.

CONCLUSION

These results provide evidence for a potential role of Le(x) trisaccharides in shaping the immune responses through, at least in part, its suppressive effect on IL-12p70 production. Considering the relative ubiquity of glycoproteins with Le(x) or similar oligosaccharides, including plant-derived (or food-derived) allergens, these findings might have a broad implication.

CLINICAL IMPLICATIONS

The adjuvant activity of Le(x) trisaccharides might aid in vaccine design and might be important in determining the allergenicity of proteins containing this or other similar structures.

[The role of fucosylation of glycoconjugates in health and disease]

Fucose is a deoxyhexose that is present in the L-configuration of many N- and O-linked oligosaccharide structures of membrane as well as soluble glycoproteins and glycolipids produced by mammalian cells. The fucose molecule is present in ABH blood group antigens and in some oligosaccharide structures belonging to the Lewis(x), Lewis(y), Lewis(a), and Lewis(b) antigens. Characteristic of fucose is its almost exclusive presence at a terminal position, i.e. not inserted in an oligosaccharide chain. Fucose can be alpha 1,2, alpha 1,3, alpha 1,4, and alpha 1,6 linked to the glycans of glycoconjugates. This predisposes fucose to play a crucial role in biological recognition events, such as cell-cell and cell-matrix interactions. In the present review the influence of fucose on the properties and biological functions of glycoproteins is described. The state of current knowledge on the role of fucosylglycotopes, fucose-containing glycans, in many physiological processes, such as fertilization, embryogenesis, fetal development, neuron transmission, leukocytes adhesion, signal transduction, and apoptosis, as well as in diseases, such as rheumatoid arthritis, cystic fibrosis, peptic ulcer disease, inflammatory process, and cancer, is summarized. Finally, some examples of changes in fucose expression and its possible determination as a marker for diseases diagnosis and monitoring are shown.

Helicobacter pylori BabA expression, gastric mucosal injury, and clinical outcome

BACKGROUND & AIMS

The blood grou.

METHODS

We compared the ability of published PCR-based methods to assess BabA status with BabA immunoblotting and Lewis b (Le(b)) binding activity assays. We also used immunoblotting to examine the relationship between clinical presentation and levels of BabA expression.

RESULTS

Immunoblotting and Le(b) binding assays for 80 strains revealed 3 levels of BabA expression: BabA high producers (BabA-H) with Le(b) binding activity, BabA low producers (BabA-L) without Le(b) binding activity, and BabA-negative. BabA-negative strains lacked the babA gene. PCR methods to determine BabA status yielded poor results. babA1 sequences were never detected. BabA expression was examined in 250 strains from Western countries and 270 strains from East Asia. The results failed to confirm any relationship between triple-positive status (cagA-positive/vacA s1/BabA-H) and clinical outcome. BabA-negative strains typically were cagA-negative/vacA s2 and were associated with gastritis. BabA-L strains showed a higher level of mucosal injury and were associated more frequently with duodenal ulcer and gastric cancer than the other groups.

CONCLUSIONS

Information gained from currently used PCR-based methods must be interpreted with caution. Le(b) binding activity does not accurately reflect the severity of mucosal damage or the clinical outcome. Quantitation of BabA expression revealed that Le(b)-nonbinding BabA-L strains are associated with higher levels of mucosal injury and clinical outcome.

Combined flow cytometry and confocal laser scanning microscopy for evaluation of BR96 antibody cancer cell targeting and internalization

BACKGROUND

Monoclonal antibodies (mAb) are important tools in the management of tumor disease, and the discovery of antibodies with both specific cancer cell targeting and capacity to enter the cells by internalization are critical to improve the therapeutic efficacy.

METHOD

Antibody cancer cell targeting and internalization properties of fluoroscein-conjugated mAb made against Lewis Y (BR96) were evaluated quantitatively and qualitatively by means of flow cytometry (FCM) and confocal laser scanning microscopy (CLSM), respectively, on cells from a rat tumor cell line (BN7005-H1D2).

RESULTS

The study demonstrated a specific binding of BR96 to LewisY (LeY) located in the cell membrane and as BR96/LeY immunocomplexes (BR96/LeY) internalized into the cytoplasm. BR96/LeY was internalized into about 15% of the cells, usually distributed throughout the cytoplasm, but also located close to the nuclei. Cytotoxic effects by BR96 were indicated, and CLSM visualized subpopulations containing cells with bound or internalized BR96/LeY that possessed morphologically pyknotic nuclei and disrupted DNA.

CONCLUSION

The spatial-temporal pattern by BR96 cell targeting and internalization processes of BR96/LeY into the cancer cells expressing LeY was demonstrated by FCM and CLSM. Used together, the FCM and CLSM techniques provide a valuable tool for preclinical analyses of antibody targeting and their capacities as carriers of cytotoxic conjugates for the use in cancer therapy.

The immunogenicity of the tumor-associated antigen Lewis(y) may be suppressed by a bifunctional cross-linker required for coupling to a carrier protein

A Lewis(y) (Le(y)) tetrasaccharide modified by an artificial aminopropyl spacer was synthesized by a highly convergent approach that employed a levulinoyl ester and a 9-fluorenylmethoxycarbonate for temporary protection of the hydroxy groups and a trichloroethyloxycarbonyl as an amino protecting group. The artificial aminopropyl moiety was modified by a thioacetyl group, which allowed efficient conjugation to keyhole limpet hemocyanin (KLH) modified by electrophilic 4-(maleimidomethyl)cyclohexane-1-carboxylate (MI). Mice were immunized with the KLH-MI-Le(y) antigen. A detailed analysis of sera by ELISA established that a strong immunoglobulin G (IgG) antibody response was elicited against the linker region. The use of a smaller and more flexible 3-(bromoacetamido)propionate for the attachment of Le(y) to KLH not only reduced the IgG antibody response against the linker but also led to a significantly improved immune response against the Le(y) antigen. This study shows that highly antigenic linkers suppress antibody responses to weak antigens such as self-antigens.

Inhibition of xenograft tumor growth and down-regulation of ErbB receptors by an antibody directed against Lewis Y antigen

The blood group-related Lewis Y antigen is expressed on the majority of human cancers of epithelial origin with only limited expression on normal tissue. Therefore, the Lewis Y antigen represents an interesting candidate for antibody-based treatment strategies. Previous experiments showed that the humanized Lewis Y-specific monoclonal antibody, IGN311, reduced ErbB-receptor-mediated stimulation of mitogen-activated protein kinase by altering receptor recycling. Here, we tested whether binding of IGN311 to growth factor receptors is relevant also to inhibition of tumor growth in vivo. Prolonged incubation with IGN311 of human tumor cell lines, which express high levels of ErbB1 (A431) or ErbB2 (SK-BR-3), resulted in down-regulation of the receptors and inhibition of cell proliferation. IGN311 inhibited the growth of tumors derived from A431 cells xenografted in nude mice. Treatment with IGN311 was associated with a down-regulation of ErbB1 in the excised tumor tissue. Importantly, these effects of IGN311 were also mimicked by the Fab fragment of IGN311. These data indicate that tumor cell growth inhibition by IGN311 cannot solely be accounted for by invoking cellular and humoral immunological mechanisms. A direct effect on signaling via binding to Lewis Y glycosylated growth factor receptors on tumor cells is also likely to contribute to the therapeutic effect of IGN311 in vivo.

Plant-derived anti-Lewis Y mAb exhibits biological activities for efficient immunotherapy against human cancer cells

Although current demands for therapeutic mAbs are growing quickly, production methods to date, including in vitro mammalian tissue culture and transgenic animals, provide only limited quantities at high cost. Several tumor-associated antigens in tumor cells have been identified as targets for therapeutic mAbs. Here we describe the production of mAb BR55-2 (IgG2a) in transgenic plants that recognizes the nonprotein tumor-associated antigen Lewis Y oligosaccharide overexpressed in human carcinomas, particularly breast and colorectal cancers. Heavy and light chains of mAb BR55-2 were expressed separately and assembled in plant cells of low-alkaloid tobacco transgenic plants (Nicotiana tabacum cv. LAMD609). Expression levels of plant-derived mAb (mAbP) were high (30 mg/kg of fresh leaves) in T1 generation plants. Like the mammalian-derived mAbM, the plant mAbP bound specifically to both SK-BR3 breast cancer cells and SW948 colorectal cancer cells. The Fc domain of both mAbP and mAbM showed the similar binding to FcgammaRI receptor (CD64). Comparable levels of cytotoxicity against SK-BR3 cells were also shown for both mAbs in antibody-dependent cell-mediated cytotoxicity assay. Furthermore, plant-derived BR55-2 efficiently inhibited SW948 tumor growth xenografted in nude mice. Altogether, these findings suggest that mAbP originating from low-alkaloid tobacco exhibit biological activities suitable for efficient immunotherapy.

Norwalk virus-specific binding to oyster digestive tissues

The primary pathogens related to shellfish-borne gastroenteritis outbreaks are noroviruses. These viruses show persistence in oysters, which suggests an active mechanism of virus concentration. We investigated whether Norwalk virus or viruslike particles bind specifically to oyster tissues after bioaccumulation or addition to tissue sections. Since noroviruses attach to carbohydrates of the histo-blood group family, tests using immunohistochemical analysis were performed to evaluate specific binding of virus or viruslike particles to oyster tissues through these ligands. Viral particles bind specifically to digestive ducts (midgut, main and secondary ducts, and tubules) by carbohydrate structures with a terminal N-acetylgalactosamine residue in an alpha linkage (same binding site used for recognition of human histo-blood group antigens). These data show that the oyster can selectively concentrate a human pathogen and that conventional depuration will not eliminate noroviruses from oyster tissue.

Characterization of murine monoclonal antibodies against Helicobacter pylori lipopolysaccharide specific for Lex and Ley blood group determinants

The cell envelope of Helicobacter pylori contains lipopolysaccharide (LPS), the O-chain of which expresses type 2 Lex and Ley blood group antigens, which mimic human gastric mucosal cell-surface glycoconjugates and may contribute to the survival of H. pylori in gastric mucosa. Here we describe the generation of monoclonal antibodies specific for Lex and Ley blood group determinants and the characterization of their binding properties using purified, structurally defined H. pylori LPS, synthetic glycoconjugates, and H. pylori cells. Analysis of oligosaccharide binding by SPR provided a rapid and reliable means for characterization of antibody affinities. One of the antibodies, anti-Lex, was of IgG3 subclass and had superior binding characteristics as compared with the commercially available anti-Lex IgM. These antibodies could have potential in the immunodiagnosis of certain types of cancer, in serotyping of H. pylori isolates, and in structure-function studies.

Qualification and application of a surface plasmon resonance-based assay for monitoring potential HAHA responses induced after passive administration of a humanized anti Lewis-Y antibody

A sensitive, surface plasmon resonance (SPR)-based assay monitoring potential human-anti-human antibody (HAHA) reactions against the monoclonal antibody (mAb) IGN311 is presented. The latter is a fully humanized Lewis-Y carbohydrate specific mAb that is currently tested in a passive immune therapy approach in a clinical phase I trial. For the SPR experiments a BIACORE 3000 analyzer was used. The ligand IGN311 was covalently coupled to the carboxy-methylated dextran matrix of a CM5 research grade chip (BIACORE). In the course of a fully nested experimental design, a four parameter logistic equation was identified as appropriate calibration model ranging from 0.3 microg/mL (lower limit of quantitation, LLOQ) to 200 microg/mL (upper limit of quantitation, ULOQ) using an anti-idiotypic mAb ('HAHA mimic') as calibrator. The bias ranged from -2.4% to 5.5% and the intermediate precision expressed as 95% CI revealed values from 5.6% to 8.3%. Specificity was evaluated using six human serum matrices from healthy donors spiked with calibrator at the limit of quantitation (LOQ) with >80% of values being recovered with less than 25% relative error. The qualified assay was applied to monitor potentially induced HAHA reactivity in 11 patients from a clinical phase I trial with passively administered IGN311. Of the 11 patients, one high HAHA responder and several low responders were identified. Protein-G depletion experiments with human serum samples revealed that the observed response is predominantly caused by IgG binding to the ligand. The characteristics of these HAHA responses were all of the so-called 'Type I' which is defined by a peak response around day 15 that decreases from this point steadily suggesting that some kind of tolerance is established. Therefore, this type of HAHA response is regarded as non critical for the patient's safety.

Enhanced efficacy of 90Y-radiolabeled anti-Lewis Y humanized monoclonal antibody hu3S193 and paclitaxel combined-modality radioimmunotherapy in a breast cancer model

Radioimmunotherapy (RIT) of solid tumor is often limited in efficacy because of restrictions in achieved tumor dose. In an effort to overcome this, the combination of RIT with other therapeutic modalities was investigated in an animal model of breast carcinoma. The rationale for this combined-modality RIT (CMRIT) was to increase the therapeutic efficacy of RIT through the use of paclitaxel to arrest cells in the radiosensitive G(2)/M phase of the cell cycle.

METHODS

In this study, the biodistribution and therapeutic efficacy of (90)Y-radiolabeled humanized anti-Lewis Y hu3S193 monoclonal antibody ((90)Y-hu3S193) RIT in combination with paclitaxel chemotherapy was explored in a Lewis Y-expressing MCF-7 tumor xenografted BALB/c nude mouse model of breast cancer.

RESULTS

Biodistribution studies demonstrated excellent tumor targeting and limited normal tissue uptake by (90)Y-hu3S193. A therapeutic study with established tumors assessed (90)Y-hu3S193 as a single agent and demonstrated significant antitumor effects in all animals receiving a single intravenous 1.85 or 3.70 MBq dose of this treatment compared with phosphate-buffered saline placebo controls (P = 0.0008 vs. P < 0.0001). Complete responses were observed in all animals in the 3.70 MBq study arm for the duration of the study. Single-dose (90)Y-hu3S193 plus paclitaxel (600 microg) CMRIT displayed improved efficacy over single-modality therapies, with a significant difference (P < 0.0001) between the mean percentage change in tumor volume in mice receiving 0.46 MBq (90)Y-hu3S193 alone and when combined with 600 mug paclitaxel.

CONCLUSION

The significant efficacy of (90)Y-hu3S193 and paclitaxel CMRIT at low radiation doses in this model of breast carcinoma indicates its therapeutic potential and warrants further investigation into this promising therapeutic approach.

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.

IGN-311. Igeneon

Igeneon, under license from Protein Design Labs, is developing IGN-311, an intravenous humanized monoclonal antibody against the Lewis Y carbohydrate antigen, as a potential agent for the passive immunotherapy of cancer, particularly epithelial tumors affecting breast, colon, gastric and pancreatic tissues. A phase I/II trial of IGN-311 was initiated in July 2005.

Improved effector functions of a therapeutic monoclonal Lewis Y-specific antibody by glycoform engineering

The aim of the present study was to produce glycosylation variants of the therapeutic Lewis Y-specific humanized IgG1 antibody IGN311 to enhance cell-killing effector function. This was achieved via genetic engineering of the glycosylation machinery of the antibody-producing host. Antibody genes were transiently cotransfected with acetyl-glycosaminyltransferase-III genes into human embryonic kidney-EBV nuclear antigen cells. A control wild-type antibody, IGN311wt, was expressed in the same host using identical expression vectors, but without cotransfection of genes for acetyl-glycosaminyltransferase-III expression. Both expression products were purified to homogeneity and characterized. The glyco-engineered expression product (IGN312-Glyco-I) showed a remarkably homogenous N-linked glycosylation pattern consisting of one major hybrid-type, non-fucosylated and agalactosylated form carrying a bisecting GlcNAc-group. Wild-type expression product (IGN311wt) on the other hand was glycosylated by a multitude of different core-fucosylated complex-type structures of variable degrees of galactosylation. Target affinity of the glyco-engineered antibody as well as heavy and light chain assembly were not affected by acetyl-glycosaminyltransferase-III expression. In vitro experiments showed a approximately 10-fold increase of antibody-dependent cellular cytotoxicity of the glyco-engineered antibody using different Lewis Y-positive target cancer cell lines (SK-BR-3, SK-BR-5, OVCAR-3, and Kato-III). Complement-mediated cytotoxicity of IGN312-Glyco-I was 0.4-fold reduced using SK-BR-5 as target cell line. The reduction of complement activation could be prevented and even converted into a slight increase of activity by using a different molecular-biological approach directing the glycosylation towards increased levels of complex N-linked oligosaccharides of bisected, non-fucosylated type, as a result of cotransfection of mannosidase II together with acetyl-glycosaminyltransferase-III.