Infants and young children with cystic fibrosis have high levels of serum sialyl Lewis(a) antigen

Previous studies suggest that serum levels of the mucin-associated sialyl Lewis(a) (Le(a)) antigen (NeuAC alpha 2-3 Gal beta 1-3 [Fuc alpha 1-4]GlcNAc beta 1...) correlate with the pulmonary status of cystic fibrosis (CF) patients who have Le(a) or Lewis(b) blood types and can form the antigen. However, there is little information on serum sialyl Le(a) antigen levels in CF patients or normal children younger than 9 y. We measured serum antigen levels using the MAb 19-9 in normal term neonates, CF infants and young children, and infants and children who had bronchopulmonary dysplasia or asthma. The mean serum sialyl Le(a) antigen level of the CF patients was 46.7 U/mL, significantly above (p < 0.01) the mean levels of the three other groups. The mean serum sialyl Le(a) levels of the three non-CF groups were not significantly different from one another or from published normal values. We conclude that serum sialyl Le(a) antigen levels are elevated early in CF, but are normal in asthma and bronchopulmonary dysplasia patients.

Relationship among Lewis phenotype, clotting factors, and other cardiovascular risk factors in young adults

An increased risk of ischemic heart disease has been reported in men with the Lewis blood group phenotype Le(a-b-). We have investigated the relationship between Lewis phenotype and cardiovascular risk factors in 1714 participants in the Coronary Artery Risk Development in Young Adults Study, an ongoing investigation on life-styles and evolution of cardiovascular risk factors. No significant differences were observed among Lewis phenotypes for body mass index, blood lipid levels, blood pressure, or clotting factors VII and fibrinogen. However, in white men with blood groups A, B, or AB, and the Le(a-b-) phenotype, significantly higher levels of factor VIII (p < 0.01) and von Willebrand factor (p < 0.03) were observed than in those with other Lewis phenotypes (Le[a+b-] or Le[a-b+]). Two-way analysis of variance indicated a significant interaction between blood group and Lewis phenotype (p = 0.0053) in terms of relationship to factor VIII. A similar trend was observed in black men with blood type A, B, or AB, and phenotype Le(a-b-) for factor VII/von Willebrand factor and in women with blood type A, B, or AB, and phenotype Le(a-b-) for factor VIII. Our data suggest that the Le(a-b-) phenotype and blood groups A, B, and AB, by virtue of their association with raised levels of factor VIII and von Willebrand factor, may be risk markers for future atherothrombotic disease.

Screening for in vitro haemolysing antibodies

The purpose of this study was to establish the frequency of the occurrence of in vitro haemolytic antibodies in donors, pregnant women and patients. The relatively high incidence of the Lewis blood group antibodies both in the group of pregnant women and patients is underlined.

Tumor-associated glycoantigen, sialyl Lewis(a) as a target for bispecific antibody-directed adoptive tumor immunotherapy

The KM231 mAb recognizing sialyl Lewis(a) (sLe(a)) epitope of glycoprotein or glycolipid expressed on various human cancers was used to prepare bispecific antibody (BSAb) containing anti-CD3 x anti-sLe(a) mAb. The effect of anti-CD3 x anti-sLe(a) BSAb on the induction of cytotoxicity by activated T cells was investigated. The activated CD3+ T cells expressing CD8 or CD4 were induced from human peripheral blood mononuclear cells by culture with recombinant IL-2 plus immobilized anti-CD3 mAb. The activated CD8+ and CD4+ T cells showed marginal cytotoxicity against tumor cells by themselves. However, addition of anti-CD3 x anti-sLe(a) BSAb resulted in a great augmentation of their cytotoxicity against gastrointestinal tumor cells. The BSAb also triggered IL-2 production of CD4+ helper/killer T cells during lysis of tumor cells. Moreover, the BSAb was demonstrated to have a potent in vivo antitumor activity against human colon cancer implanted in nude mice by combination with CD4+ helper/killer cells. These results demonstrated that sLe(a) antigen might be a good target molecule for BSAb-directed adoptive tumor immunotherapy.

Specificity analysis of blood group Lewis-y (Le(y)) antibodies generatedagainst synthetic and natural Le(y) determinants

Le(y)-reactive monoclonal antibodies (mAbs) were generated in mice by immunization with synthetic Le(y) neoglycoproteins or with Le(y)-expressing cells. Serological analysis indicated that mAbs raised against synthetic Le(y) (i) reacted strongly with synthetic Le(y) but poorly with natural Le(y), (ii) cross-reacted with Le(x) or H-type 2 structures, and (iii) were IgG1, IgG2a, or IgG2b. mAbs raised against Le(y)-expressing cells (i) reacted with both synthetic Le(y) and natural Le(y), (ii) were of two types: cross-reactive with Le(x) or H-type 2 structures or specific for Le(y), and (iii) were IgM or IgG3. One of the mAbs raised against natural Le(y), mAb 3S193 (IgG3), showed high specificity for Le(y) in ELISA tests with synthetic Le(y) and Le(y) containing glycoproteins and glycolipids; it also reacted strongly in rosetting assays and cytotoxic tests with Le(y)-expressing cells. mAb 3S193 did not lyse O, A, AB, and B human erythrocytes in the presence of human complement. In flow cytometry, there was weak reactivity with granulocytes, a reactivity also observed with two previously described highly specific Le(y) mouse mAbs--BR55-2 (IgG3) and B3 (IgG1). A humanized version of mAb 3S193 has been constructed, and the specificity pattern and reactivity for Le(y) remain very similar to mouse mAb 3S193.

Expression of Lewis histo-blood group glycolipids in the plasma of individuals of Le(a+b+) and partial secretor phenotypes

Red cell Lewis antigens are carried by glycosphingolipids passively absorbed from plasma. Plasma was collected from a spectrum of individuals with normal and unusual Lewis/secretor phenotypes in order to investigate the glycolipid basis for the unusual phenotypes. Samples were obtained from: a Le(a+b-) ABH nonsecretor who secreted Lewis substances; a Le(a+b-) partial secretor; Le(a+b+) partial secretors; Le(a+b+) secretors; and a full range of normal Lewis/secretor phenotypes as controls. The Le(a+b+) samples represented Polynesian, Asian and Réunion Island ethnic backgrounds. Nonacid glycolipids were prepared, separated by thin-layer chromatography, and then immunostained with potent monoclonal antibodies of known specificity. Despite different serological profiles of the Le(a+b-) and Le(a+b+) Polynesian samples, their plasma glycolipid expressions were very similar, with both Le(a) and Le(b) co-expressed. The copresence of Le(a) and Le(b) in Le(a+b+) samples is in marked contrast to Caucasians with normal Lewis phenotypes, who have predominantly either Le(a) or Le(b). These results suggest that there is a range of the secretor transferases in different individuals, possibly due to different penetrance or to several weak variants. We also show that Lewis epitopes on longer and/or more complex core chains appear to be predominant in the Polynesian Le(a+b+) samples. The formation of these extended glycolipids is compatible with the concept that in the presence of reduced secretor fucosyltransferase activity, increased elongation of the precursor chain occurs, which supports the postulate that fucosylation of the precursor prevents or at least markedly reduces chain elongation.

First synthesis of the 3'-sulfated Lewis(a) pentasaccharide, the most potent human E-selectin ligand so far

Tri- and pentasaccharides of Lewis(a)-type, sulfated at position 3 of the outer galactose, have been prepared using the new 4-methoxybenzyl glycoside of N-acetylglucosamine 5 as starting material. The synthesis of the pentasaccharide 2 was achieved through a beta-stereoselective coupling of an alpha-trichloroacetimidate activated form of the N-acetamido protected trisaccharide 18 on to a 3',4'-unprotected lactose derivative.

Systematic synthesis of N-methyl-1-deoxynojirimycin-containing, Le(x), Le(a), sialyl-Le(x) and sialyl-Le(a) epitopes recognized by selectins

A systematic synthesis of the N-methyl-1-deoxynojirimycin-containing oligosaccharides related to the Lewis x, Lewis a, sialyl-Lewis x and sialyl-Lewis a antigens has been achieved. The couplings of the suitably protected 1-deoxynojirimycin derivative 10 with methyl-1-thioglycosides (glycosyl donors) of L-fucose (11), D-galactose (15) and alpha-sialyl-(2-->3)-D-galactose (27) were carried out by using dimethyl(methylthio)sulfonium triflate (DMTST) or N-iodosuccinimide/trifluoromethanesulfonic acid (NIS/TfOH) as the glycosyl promoter. The resulting di- and tri-saccharides were each converted, by further cross glycosylations with 11, 15 or 27, to the desired tri- and tetra-saccharides 3-6 that inhibit the recognition between sialyl-Lewis x and selectins, a family of leukocyte cell adhesion molecules.

[Expression and prognostic indicators of type 1 and type 2 Lewis blood group antigens in colorectal cancers]

The immunohistochemical analysis using the monoclonal antibodies to the blood group antigens was performed on the tissues of 387 colorectal cancers and 307 normal colonic tissues, and the relation between expression of these antigens and prognosis of the patients with stage 2 was also investigated. La, Le(b), and CA 19-9 were used for type 1 antigens, and Le(x), Le(y), and Sialyl Le(x) for type 2, respectively. Expression of Ca 19-9 and Silyl Le(x) remarkably increased in cancers throughout the colorectum. Le(b) and Le(y) were expressed in only 0-17% of the normal distal colon, but in almost colonic tumors. Therefore CA 19-9 and Sialyl Le(x) are tumor-associated antigens in the whole colorectum, and Leb and Le(y) in the distal colon. Expression of CA 19-9 in primary tumor provided more prognostic information and risk of liver metastasis than other Lewis blood group antigens.

[The isoantigenic differentiation of human body tissues and excretions by using new immune reagents]

A priority technology has been developed to obtain highly effective group-specific reagents for some immunological methods, for the adsorption-elution test and immunofluorescence, first of all. Rapid method making use of these reagents are offered to be used for detection of AB0, MNSs, P, and Le antigens in liquid blood, in trace amounts of tissues, and human excretions in objects of material evidence in forensic medical expert evaluation. These reagents may be used in blood transfusion service as well.

Human tumor-associated Le(a)-Le(x) hybrid carbohydrate antigen IV3(Gal beta 1-->3[Fuc alpha 1-->4]GlcNAc)III3FucnLc4 defined by monoclonal antibody 43-9F: enzymatic synthesis, structural characterization, and comparative reactivity with various antibodies

Two Le(a)-cross-reacting monoclonal antibodies (mAbs) were previously established which define complex tumor-associated carbohydrate antigens. The first mAb, 43-9F, was raised against human squamous cell lung carcinoma and shows preferential reactivity with various human cancers over normal cells. Its tumor cell binding activity is best inhibited by a milk oligosaccharide characterized as Le(a)-Le(x) [Mårtensson, S., et al. (1988) Cancer Res. 48, 2125], Gal beta 1-->3[Fuc alpha 1-->4] GlcNAc beta 1-->3Gal beta 1-->4]Fuc alpha 1-->3]-GlcNAc beta 1-->3Gal beta 1-->4Glc (1). The second mAb, ST-421, was raised against human gastric cancer xenograft in nude mice and found to have strong tumor growth-suppressing activity in nude mice. The epitope recognized by ST-421 was chemically identified as Le(a)-Le(a), Gal beta 1-->3 [Fuc alpha 1-->4]GlcNAc beta 1-->3Gal beta 1-->3-[Fuc alpha 1-->4] GlcNAc beta 1-->3Gal beta 1-->4Glc (2) [Stroud, M.R., et al. (1991) J. Biol. Chem. 266, 8439]. Both 43-9F and ST-421 cross-react with Le(a). Identification of the 43-9F antigen as structure 1 (Le(a)-Le(x)) is tentative since it was not based on isolation and chemical characterization of antigen from tumor cells or tissues. We therefore synthesized structure 1 starting from sialyl-nor-hexaosylceramide (VI3NeuAcnLc6), with sequential enzymatic hydrolysis by sialidase and beta-galactosidase followed by addition of beta 1-->3Gal with beta 1-->3 galactosyltransferase. This yielded the hybrid type 1/type 2 chain core structure IV3-(Gal beta 1-->3GlcNAc)nLc4, which was fucosylated with alpha 1-->3/4 fucosyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)

[P1 blood group, secretion status and susceptibility to asymptomatic bacteriuria in diabetes]

Blood-group antigens found on uroepithelial cells and in the secretions may affect bacterial adherence and thereby the predisposition to urinary tract infection. We determined P1, Lewis-blood-group phenotype and secretor status in patients with diabetes mellitus: 12 with asymptomatic bacteriuria and 7 without its presence. There was no difference between the two groups in the distribution of the P1 phenotype. There was also no statistical difference in the distribution of the Lewis phenotype and secretor status, although there appeared to be general trend of higher number of Le (a+b-) phenotype and non-secretors present in the asymptomatic bacteriuria group. Further studies are necessary to determine the role of blood groups and secretor status in the pathogenesis and susceptibility to urinary tract infection.

Expression of tumor-associated glycoantigen, sialyl Lewis(a), in human head and neck squamous cell carcinoma and its application to tumor immunotherapy

The glycoantigen sialyl Lewis(a) (sLe(a)) is widely expressed on a variety of gastrointestinal tumor cells. Here, we immunohistochemically demonstrated the expression of sLe(a) antigen in 54% (7 out of 13) of human head and neck squamous cell carcinoma (H-NSCC) samples. Frequent expression of sLe(a antigen was also demonstrated on a variety of H-NSCC cell lines using flow cytometry. Both CD4+ and CD8+ T cells, which were activated with immobilized OKT3 monoclonal antibody plus interleukin-2, showed augmented cytotoxicity against sLe(a)-positive H-NSCC, including autologous tumor cells, on targeting with anti-CD3 x anti-sLe(a) bispecific antibody, suggesting that sLe(a) antigen is a good target molecule for bispecific antibody-dependent adoptive tumor immunotherapy of human head and neck cancer.

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 Le(a) and Le(x) antigens, whereas secretors expressed higher levels of Le(b) and Le(y) 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.

Immunocytochemical localization of Lewis blood group antigens in human salivary glands

We demonstrated the immunohistochemical distribution of Le-a and Le-b blood group antigens in human major and minor salivary glands at the ultrastructural level by applying a post-embedding immunogold staining method. In secretors' glands, a faint Le-a reactivity was found only in mucous droplets, whereas Le-b antigen was intensely stained in secretory granules of most mucous cells, in those of intercalated duct cells, in the pale granular matrix of some serous cells, and, when osmication was omitted, in cytoplasmatic vesicles and cell surfaces of striated ducts. In the submandibular gland of a non-secretor, Le-a antigen was considerably stained in mucous droplets, whereas Le-b reactivity was restricted to the striated duct cells. These results indicate that the secretor status affects the secretion of Lewis antigens by mucous, serous, and intercalated duct cells but not the presence of Le-b as a surface antigen in striated duct cells.

Detection of microbial surface antigens that bind Lewis(a) antigen

There is evidence that the Lewis(a) blood group antigen is one of the receptors for a number of potentially pathogenic microorganisms. To determine how widely distributed the microbial adhesins are that bind this antigen, anti-idiotypic antibodies produced against monoclonal anti-Lewis(a) were used in coagglutination assays to screen a variety of species. The following were agglutinated: 7/7 strains of Staphylococcus aureus; 10/19 (53%) strains of Neisseria meningitidis; 8/13 (62%) strains of Haemophilus influenzae; 1/3 strains of Helicobacter pylori; 1/2 strains of Neisseria gonorrhoeae; 1/2 strains of Candida albicans. The application of the anti-idiotypic antibodies to studies of host cell receptors, isolation of adhesins and development of new epidemiological typing reagents is discussed.

Quantitative analysis of Le(a) and Le(b) antigens in human saliva

We have measured the H type 1, Le(a) and Le(b) antigens in the saliva from 129 Japanese individuals by a time-resolved europium ion fluorometric immunoassay using artificial antigen-albumin complexes as the reference substances. We confirmed that the amount of Le(b) was larger than that of Le(a) in the saliva from secretors (Le(a-b+)) and vice versa in the saliva from nonsecretors (Le(a+b-)). Unexpectedly, we discovered appreciable amounts of Le(b) with small amounts of H type 1 in the saliva from the nonsecretors. The concentration of Le(b) was about 10, 6 and 35% of the concentration of the Le(a) in the saliva from the nonsecretors of the A, B and O groups, respectively. The possible formation of Le(b) from Le(a), in addition to the formation of Le(b) from H type 1, in the salivary glands is discussed.

Role of P-selectin and leukocyte activation in polymorphonuclear cell adhesion to surface adherent activated platelets under physiologic shear conditions (an injury vessel wall model)

Carbohydrate moieties on leukocytes adhere to activated platelets via P-selectin under static binding condition studies. We characterize polymorphonuclear cell (PMN) surface interactions with surface adherent platelets and the PMNs response, under physiologic flow conditions corresponding to a shear of 100 s-1, in an in vitro flow chamber. Fluorescent labeled PMNs with red blood cells were drawn through a transparent flow channel and visually quantitated over 30 minutes, interacting with a confluent monolayer of activated, shear-spread platelets expressing P-selectin. PMN adhesion was saturable (2,250 +/- 350/mm2), and time and cation (Ca2+, Mg2+) dependent, and PMNs did not bind to the experimental surface in the absence of a platelet monolayer. P-selectin antibodies completely abolished PMN adhesion in a concentration-dependent manner with half inhibition at 70 micrograms/mL. Antibodies to a putative P-selectin receptor CD15 (80H5 and MMA) maximally inhibited PMN adhesion by 73% and 10%, respectively. Adherent PMNs appeared morphologically activated and flow cytometric analysis of adherent PMNs confirmed activation because CD11b and CD18 surface expression was upregulated (100% and 27%, respectively), whereas L-selectin was downregulated (55%) compared with control nonadherent PMNs. In the presence of the metabolic inhibitor sodium azide (0.02% and 0.1%) there was a 23% +/- 9% and 51% +/- 3% decrease, respectively, in PMN adhesion at 100 s-1. Thus, P-selectin is required for PMN adhesion to a pathophysiologic surface of activated adherent platelets at physiologic shear rates. Furthermore, a secondary step involving PMN activation after platelet binding appears necessary for complete (irreversible) adhesion to occur. This unique flow cell provides a model to explore, under controlled conditions, biologic mechanisms and ligands involved in leukocyte-platelet binding that play important roles in PMN localization at sites of thrombosis and vascular injury.

Taste bud expression of human blood group antigens

Some human blood group antigens are expressed by rodent epithelial cells at different stages of differentiation. Since adult taste cells are continually replaced throughout life, we investigated the expression of the H, B, A and Lewisb blood group determinants by cells of the rat fungiform, foliate and vallate papillae. We employed antibodies against the trisaccharide structures of the H, B, and A blood group antigens and against the Lewisb blood group epitope in studies of normal and denervated taste buds. The antibody against the H antigen reacted with the majority of cells in all taste buds and with cells in the spinous layer of the tongue epithelium. The B antigen was expressed by the majority of taste cells but not by other epithelial cells. The expression of the A antigen was significantly less in the fungiform taste buds than in the vallate or foliate taste buds. The A antigen was also abundantly expressed in the acini of the lingual salivary glands. The Lewisb epitope was expressed by a subset of cells in taste buds of the fungiform, foliate and vallate papillae. Taste buds are trophically dependent upon gustatory nerve innervation. Transection of the chorda tympani or the IXth nerve resulted in the loss of expression of these molecules from the gustatory epithelium, indicating that they are expressed only on differentiated taste cells. The blood group antigens are lactoseries carbohydrates; they are differentially expressed in developing cochlear hair cells and olfactory neurons and may play roles in cell-cell recognition, adhesion, and other interactions important in the developing nervous system. They could have similar functions in the taste and olfactory systems, where the receptors are continually renewed and new synapses between the receptors and their neural targets continually form.

An immunohistochemical employer monoclonal antibodies against Le(a), sialyl Le(a), Le(x), and sialyl Le(x) antigens in primary colorectal, carcinomas and lymph node and hepatic lesions

The immunohistochemical expression of sialylated and non-sialylated forms of both Le(x) and Le(a) were studied in 87 carcinomas and 42 normal mucosal specimens of colon and rectum, as well as in 32 metastatic lymph nodes and 9 hepatic lesions, using an indirect immunoperoxidase staining. Their antigens were expressed in normal mucosa with the following frequencies: Le(a), 95.2% (40/42); sialyl Le(a), 88.1% (37/42); Le(x), 95.2% (40/42); and sialyl Le(x), 17.0% (7/42), whereas in carcinomas, the respective rate of frequency were: 78.2% (68/87); 78.2% (68/87); 90.8% (79/87); and 93.1% (81/87). Sialyl Le(x) antigen showed the highest tumor specificity compared to other antigens. In three normal mucosal specimens and four carcinomas with Le(a-b-) phenotype, the expression of type 1 antigens (Le(a) and sialyl Le(a)) was not consistent, whereas type 2 antigens (Le(x) and sialyl Le(x)) were consistently observed in carcinomas. The staining of type 1 antigens and Le(x) was decreased in metastatic lesions compared with primary carcinomas, whereas sialyl Le(x) antigen had the same positive-staining rate in both. Metastatic carcinoma expressed the sialylated form more predominantly than the non-sialylated form in type 2 antigens whereas the opposite result was observed in type 1 antigens. These results suggested that: (a) sialyl Le(x), defined by monoclonal antibody CSLEX1, may be useful as a tumor-associated antigen in colorectal carcinoma, and (b) the alteration of Lewis-related carbohydrate antigens in cancer cell membranes, including sialylation and/or aberrant glycosylation, may be related to metastatic behavior.

Anti-tumor antibody BR96 blocks cell migration and binds to a lysosomal membrane glycoprotein on cell surface microspikes and ruffled membranes

BR 96 is an internalizing antibody that binds to Lewis Y (Le(y)), a carbohydrate determinant expressed at high levels on many human carcinomas (Hellström, I., H. J. Garrigues, U. Garrigues, and K. E. Hellström. 1990. Cancer Res. 50:2183-2190). Breast carcinoma cell lines grown to confluence bind less BR96 than subconfluent cultures (Garrigues, J., U. Garrigues, I. Hellström, and K. E. Hellström. 1993. Am. J. Path. 142:607-622). However, when the confluent cells are induced to migrate by scratch wounding, they again bind BR96 suggesting that antigens bearing the Le(y) determinant may promote cell migration. In the present study, BR96 was found to be highly enriched on microspikes and ruffled membranes, cell surface structures involved in cell migration. In addition, BR96 was a potent inhibitor of cell migration in vitro. When stationary BR96 treated cells were exposed to fresh culture media, membrane ruffles and microspikes developed at the cell margin and migration resumed. Immunogold microscopy showed that BR96 antigens were enriched on these membrane protrusions. BR96 cell surface immunoprecipitation analysis of 3H-glucosamine labeled breast carcinoma cells identified antigens with approximate molecular weights of 135 kd (upper antigen) and 85 kd (lower antigen). A short amino terminal sequence (8 residues) of the upper antigen matched that of human lysosomal membrane glycoprotein 1 (LAMP-1). In addition, the upper antigen was detected on immunoblots probed with anti-LAMP-1, and within the intracellular compartment BR96 was found predominantly in endosomes and lysosomes. A soluble LAMP-1/immunoglobulin fusion protein (LAMP-1/Ig) was transiently expressed in both BR96 binding and nonbinding cell lines. Immunoblot analysis of LAMP-1/Ig's from the various cell lines showed that (a) acquisition of the BR96 epitope is probably controlled at the level of polylactosamine modification (e.g., fucosylation) rather than LAMP-1 gene expression; (b) alternate forms of LAMP-1/Ig comigrate with the lower BR96 antigen raising the possibility that it may be a degradation product of the upper antigen; and (c) LAMP-1/Ig expressed in 3396 breast carcinoma cells has approximately 30-fold more BR96 epitopes than LAMP-1/Ig from non-tumorigenic mammary epithelial cells. Together these data indicate that a major BR96 antigen, LAMP-1, is present on unique cell surface domains involved in cell locomotion as well as membranes of the endocytic compartment. Altered glycosylation of LAMP-1 expressed in transformed cells may contribute to their ability to disseminate.

Characterization of the E-selectin ligand on NK cells

In this study we demonstrate that human CD56+CD16+/CD3- NK cells adhere to the E-selectin expressed by stimulated HUVEC in a sialidase- and Ca(2+)-dependent manner, and express a silylated Lex adhesion structure. We have characterized this sLe(x) epitope on NK cell in detail and show here that the sLe(x) on NK cells was not recognized by the CSLEX1 Ab, but was readily identified by two anti-di-sLe(x) Abs, KM-93 and FH-6. Furthermore, cleaving sialic acid with a sialidase treatment revealed a pool of Le(x) epitopes on the NK cells surface, providing further proof that NK cells express sLe(x) epitopes. Extensive protease treatments did not cleave the sLe(x) epitope from NK cells, which suggests that it could be linked to a lipid backbone. This di-sLe(x) was able to mediate adhesion to E-selectin, suggesting that it represents an essential part or is closely related to a selectin ligand on NK cells. We were also able to show that NK cells possess several alpha 2,3 sialyltransferases and alpha 1,3 or alpha 1,3/4 fucosyltransferases. These enzymes are crucial in the synthesis of sLe(x) epitopes on cell surfaces. Taken together, we provide evidence that NK cells have a di-sLe(x) oligosaccharide capable of adhesion to E-selectin, and NK cells have the machinery (i.e., relevant transferases) to generate these sialylated Lewis oligosaccharides.

Quantitative analysis of Lewis antigens on erythrocytes by flow cytometry

We have developed a method for the quantitative analysis of Lewis antigens on human red blood cells (RBC) using immunofluorescence labeling and flow cytometry. Initially, Lewis a and Lewis b (Le(a) and Le(b)) antigens were labeled with monoclonal anti-Le(a) or anti-Le(b) antibodies followed by labeling with the fluorescein isothiocyanate (FITC)-conjugated second antibody. This method was not sensitive enough to identify the Lewis antigens on RBC, although the FITC method is very commonly used for antigens on white blood cells. Next, we selected the enhanced labeling technique using the avidin-biotin procedure. Biotinylated anti-mouse IgM was used for the second label and the reaction with R-phycoerythrin (RPE)-conjugated streptavidin followed to produce the fluorescence. The method was found to be effective for our objectives. From the results analyzed by the enhanced labeling technique, differences were not found in either the levels of the antigen-positive percentage and the peak mean channel of Le(a) antigens on RBC in the groups of blood type O and A (in ABO system). On the other hand, both the levels of Le(b) antigens on RBC were higher in the groups of blood type O than in those of blood type A. We found both Le(a) and Le(b) antigens on RBC from a few blood type O subjects. We conclude that enhanced labeling and flow cytometry constitute a useful technique for the determination of Lewis antigens on RBC and that this method enables the precise quantification of such antigens.

Native and sialic acid masked Lewis(a) antigen reactivity in medullary thyroid carcinoma. Distinct tumour-associated and prognostic relevant antigens

Forty-six medullary thyroid carcinomas (MTC) were subjected to a qualitative and quantitative characterization of native and sialic acid masked Lewis(a) (Le(a)) antigens. Immunohistochemical investigations included monoclonal antibodies (MABs) directed against alpha(2,3)-sialyl-Le(a), i.e. CA19-9 (MAB 19-9), native Le(a) (MAB anti Le(a)) and alpha(2,3)sialyl type 1 structure, i.e. CA 50 (MAB C50). To detect sialic acid masked Le(a) reactivity, MAB anti-Le(a) was also applied to native and enzymatically desialylated tissue sections with and without masking of sialic acid residues by sialic acid and sequence specific lectins. Only 7 MTC (15%) displayed a weak expression of CA19-9, while 16 (33%) showed moderate positive staining for native Le(a). Twenty-seven tumours exhibited a strong staining by the N'ase MAB anti Le(a) staining sequence. The latter could most effectively be inhibited by the simultaneous masking of alpha(2,3)-and alpha-(2,6)-linked sialic acid residues due to the competitive binding of sialic acid and sequence specific lectins: Maackia amurensis agglutinin (specific alpha(2,3)-linked sialic acid) and Sambucus nigra agglutinin (specific alpha(2,6)-linked sialic acid). Thus, in MTC the major portion of sialic acid masked Le(a) antigen reactivity is different from that detected by the MAB 19-9. The antigen reactivity is probably due to Le(a) structures containing both alpha(2,3) and alpha(2,6)-linked sialic acid residues. A highly significant correlation between the expression of CA50 and that detected by the N'ase MAB anti-Le(a) staining sequence indicates that the alpha(2,3)-sialyl type 1 chain represents a common intermediate structure within the pathway of the biosynthesis of sialylated Le(a) antigens, excluding the formation of CA19-9 via the formation of the disialyl type 1 structure. This is subsequently fucosylated to the corresponding sialic acid masked Le(a). Preliminary clinicopathological studies indicate that the sialic acid masked Le(a) antigens detected by the N'ase MAB anti-Le(a) staining sequence are related to biologically aggressive MTC.