Expression of the 3-fucosyl N-acetyllactosamine (CD 15) antigen in normal, metaplastic, dysplastic, and neoplastic squamous epithelia

Lewis blood group and CEA related antigens; coexpressed cell-cell adhesion molecules with roles in the biological progression and dissemination of tumours

The Lewis blood group and carcinoembryonic antigen (CEA) related antigens have adhesive functions in human tissues, with roles in embryonic sorting and migration of cells (organogenesis), differentiation and protection of normal mucosal tissues, migration of neutrophils, bacterial binding, and tumour differentiation and dissemination. In the key areas of mucosal protection, neutrophil binding, and tumour metastasis, they are often coexpressed on the outer cell membrane, with Lewis blood group antigens forming the terminal carbohydrate chains on a CEA related glycoprotein backbone. The central role of these antigens in the mechanism of neutrophil binding to endothelium in inflammation highlights a fascinating paradigm for tumour cell dissemination and metastasis, and expression is linked to disease prognosis. This review outlines the structure, function, and comparative roles of these antigens in human tissues.

Expression and modulation of the Lewis x antigen (CD15) on the T cell line Molt-4

The T cell lines Molt-4 and H9 exhibited a characteristic distribution of the cell adhesion molecule Lewis x (CD15, lacto-N-fucopentanose III) showing an unusually broad peak by flow cytometry ranging from cells without CD15 to cells with high expression. The cytokines IL-1, IL-2, IFN-beta, IFN-gamma, and TNF-alpha, known to activate T cells, did not affect CD15 expression. However, phorbol myristate acetate and the thymic peptide extract Thymex-L were able to enhance both the number of CD15-positive cells and the median fluorescence. The effects of both inducers were dose- and time-dependent. An additive or synergistic effect was not seen. These data suggest that phorbol esters and distinct thymic peptides can modulate the expression of the cell surface antigen CD15.

Engagement of the Lewis X Antigen (CD15) Results in Monocyte Activation

We previously reported that monocyte adhesion to tumor necrosis factor-α (TNF-α)–treated endothelial cells increased expression of tissue factor and CD36 on monocytes. Using immunological cross-linking to mimic receptor engagement by natural ligands, we now show that CD15 (Lewis X), a monocyte counter-receptor for endothelial selectins may participate in this response. We used cytokine production as a readout for monocyte activation and found that CD15 cross-linking induced TNF-α release from peripheral blood monocytes and cells from the monocytic cell line MM6. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) showed an increase in steady-state TNF-α mRNA after 3 to 4 hours of cross-linking. CD15 cross-linking also concomitantly increased interleukin-1β (IL-1β) mRNA, while no apparent change was observed in the levels of β-actin mRNA, indicating specificity. To examine transcriptional regulation of cytokine genes by CD15 engagement, a CAT plasmid reporter construct containing IL-1β promoter/enhancer sequences was introduced into MM6. Subsequent cross-linking of CD15 increased CAT activity. CD15 engagement by monoclonal antibody also attenuated IL-1β transcript degradation, demonstrating that signaling via CD15 also had posttranscriptional effects. Nuclear extracts of anti-CD15 cross-linked cells demonstrated enhanced levels of the transcriptional factor activator protein-1, minimally changed nuclear factor-κB, and did not affect SV40 promoter specific protein-1. We conclude that engagement of CD15 on monocytes results in monocyte activation. In addition to its well-recognized adhesive role, CD15 may function as an important signaling molecule capable of initiating proinflammatory events in monocytes that come into contact with activated endothelium.

Engagement of the Lewis X Antigen (CD15) Results in Monocyte Activation

We previously reported that monocyte adhesion to tumor necrosis factor-α (TNF-α)–treated endothelial cells increased expression of tissue factor and CD36 on monocytes. Using immunological cross-linking to mimic receptor engagement by natural ligands, we now show that CD15 (Lewis X), a monocyte counter-receptor for endothelial selectins may participate in this response. We used cytokine production as a readout for monocyte activation and found that CD15 cross-linking induced TNF-α release from peripheral blood monocytes and cells from the monocytic cell line MM6. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) showed an increase in steady-state TNF-α mRNA after 3 to 4 hours of cross-linking. CD15 cross-linking also concomitantly increased interleukin-1β (IL-1β) mRNA, while no apparent change was observed in the levels of β-actin mRNA, indicating specificity. To examine transcriptional regulation of cytokine genes by CD15 engagement, a CAT plasmid reporter construct containing IL-1β promoter/enhancer sequences was introduced into MM6. Subsequent cross-linking of CD15 increased CAT activity. CD15 engagement by monoclonal antibody also attenuated IL-1β transcript degradation, demonstrating that signaling via CD15 also had posttranscriptional effects. Nuclear extracts of anti-CD15 cross-linked cells demonstrated enhanced levels of the transcriptional factor activator protein-1, minimally changed nuclear factor-κB, and did not affect SV40 promoter specific protein-1. We conclude that engagement of CD15 on monocytes results in monocyte activation. In addition to its well-recognized adhesive role, CD15 may function as an important signaling molecule capable of initiating proinflammatory events in monocytes that come into contact with activated endothelium.

Endocytosis of fluorescent microspheres by human oesophageal epithelial cells: comparison between normal and inflamed tissue

This paper examines the presence and characteristics of endocytosis by oesophageal epithelial cells. Biopsy specimens from normal and inflamed oesophagus were incubated in organ culture with fluorescent microspheres (0.1 and 0.01 microns diameter). These markers were taken into early endosomes and the lysosomes of both the smaller differentiating prickle cells and the larger mature squamous cells. Confocal and electron microscopy showed that markers passed to the early endosomes and the lysosomes by endocytosis. The process was energy dependent. Larger, 1 micron microspheres adhered to the epithelial cells but were not phagocytosed. Disaggregated cells were analysed by flow cytometry. Microspheres were endocytosed in proportion to the concentration in the culture medium in a dose dependent manner. Cells from inflamed oesophagus were significantly smaller (p = 0.013) and took up significantly more microspheres than cells from normal biopsy specimens (p = 0.015). In conclusion, endocytosis occurs in oesophageal epithelial cells and is increased in inflammation.

Differential expression of Lewis(x) and sialyl-Lewis(x) antigens in fetal human neural cells in culture

Lewis(x) is a cell-surface carbohydrate antigen defined by the trisaccharide structure, Gal beta 1-->4 (Fuc alpha 1-->3) GlcNAc. Expression of Lewis(x) and sialyl-Lewis(x) antigens in primary cell cultures isolated from fetal human brains of 12-15 weeks gestation was investigated by double immunolabelling with antibodies against monomeric Lewis(x) (4C9), oligomeric Lewis(x) (FH4), and sialylated oligomeric Lewis(x) (FH6) antigens and cell type-specific markers. The monomeric Lewis(x) antigen was expressed in more than 15% of astrocytes and 100% of oligodendrocytes, whereas it was not identified in neurons or in microglia. The oligomeric Lewis(x) antigen was undetectable in any cell types, while the sialylated oligomeric Lewis(x) antigen was expressed in more than 95% of microglia but not in any other cell types. The cell type-specific expression of Lewis(x) and sialyl-Lewis(x) antigens in fetal human glial cells suggests that these fucose-containing carbohydrate molecules play roles in intercellular recognition between distinct cell types during the development of the human central nervous system.

Patterns of CEA-related antigen expression in invasive squamous carcinoma of the cervix

The recognition of an adhesive role for the CEA-related antigens emphasizes the need for clear demonstration of the changes in CEA expression and subcellular localization between normal and neoplastic tissues. Using a panel of monoclonal and polyclonal antibodies, membranous and cytoplasmic CEA expression was seen in 50 invasive cervical squamous carcinomas in four distinct patterns dependent on tumour type and differentiation. Membranous CEA expression is a marker of differentiation in squamous carcinomas and may influence tumour behaviour and hence patient survival. Strong CEA positivity was seen on the endothelium of vessels containing tumour in ten cases where vascular metastases were prominent. Staining of these ten cases revealed concomitant sialated Lewis X positivity in tumour cells with weak endothelial positivity in three cases; cervical squamous tumour cells may localize to vascular endothelium, and hence disseminate, through specific binding of CEA and/or sialated Lewis X.

Expression of CD15 (FAL) on myeloid cells and chromosomal localization of the gene

Different CD15 murine monoclonal antibodies were studied. These antibodies appeared to react specifically with the human myeloid-lineage-derived cell types in both peripheral blood and bone marrow. The antigens recognized by these antibodies were immunoprecipitated from lysates of 125I-labelled neutrophilic PMNs of healthy donors and subsequently analysed by electrophoresis on SDS-polyacrylamide gel and autoradiography. All antibodies precipitated the same membrane polypeptides from the membrane-iodinated PMN lysates: 105 and 150-kDa as most prominent, together with 260-, 230-, 67- and 52-kDa polypeptides. Absorption studies were performed with synthesized carbohydrate molecules. Antibody B4.3 appears to be directed against 3-alpha-fucosyl-N-acetyl-lactosamine (FAL). Competition experiments with 125I-labelled B4.3 demonstrated complete inhibition of binding by B4.3 and three other CD15 antibodies (VIM D5, UJ308, MI/N1), and partial inhibition by three additional antibodies (FMC10, FMC12, FMC13), indicating binding to the same antigenic structure. None of the antibodies reacted with monocytes using the immunofluorescence technique, but after neuraminidase digestion of these cells, positive reactions were obtained with all antibodies. Immunoprecipitation with lysates of both native and neuraminidase-digested monocytes showed no polypeptide bands. Monocytic differentiation of the myeloid cell line HL60 by 12-O-tetradecanoylphorbol-13-acetate (TPA) was accompanied by a decrease in reactivity with the antibodies, which could be reversed by neuraminidase digestion. This indicates that 3-alpha-fucosyl-N-acetyl-lactosamine is masked for the detection with antibodies upon monocytic differentiation by sialylation. Human x mouse myeloid cell hybrids were obtained after fusion of human myeloid cells and the HPRT-deficient murine myeloid cell line WEHI-TG.(ABSTRACT TRUNCATED AT 250 WORDS)

Flow cytometry of oesophageal mucosal biopsies; epidermal growth factor receptor, and CD15

Flow cytometry may be used to examine the properties of single or isolated cells. We have shown that it is possible to disaggregate and label oesophageal epithelial cells for two surface markers, CD15 and epidermal growth factor receptor. We have previously demonstrated these markers in oesophageal squamous cells using immunoperoxidase techniques. These labelled disaggregated cells could then be measured by flow cytometry.

Membranous expression of carcinoembryonic antigen (CEA) in the normal cervical squamous mucosa

Using a panel of polyclonal and monoclonal antibodies to CEA-related antigens in paraffin-processed cervical biopsies, CEA and NCA expression has been demonstrated on the cell membrane of normal mature cervical squames. Cytofluorimetry of disaggregated cervical squames confirmed membranous expression and immunogold labelling of ultrathin cryostat sections localized CEA to the glycocalyx and to within cytoplasmic membrane-bound vesicles of mature squames. Immunoblotting of cervical tissue showed that most of the CEA reactivity was expressed as a glycoprotein of molecular weight around 180 k, probably CEA itself. Localization of the CEA to the cell membrane of mature cervical squames suggests a key role for these antigens in maintaining the integrity of the squamous mucosa, through the putative function of an adhesion molecule.

Uptake of horseradish peroxidase by human oesophageal explants over 24 h

Human oesophageal biopsies, endoscopically and histologically normal, were incubated in Ham's F10 for periods up to 24 hours in the presence of horseradish peroxidase. The fluid phase marker was taken up most avidly by the prickle cells but to a lesser extent in the functional layers and by basal cells. Endocytosed markers proceeded to multivesicular bodies (segrosomes). Horseradish peroxidase was later deposited in lysosome-like structures and also in the Golgi apparatus. The lesser uptake by the functional cells may represent reduced access of the marker to the cells due to the intercellular barrier.

PADGEM-dependent adhesion of platelets to monocytes and neutrophils is mediated by a lineage-specific carbohydrate, LNF III (CD15)

PADGEM (platelet activation-dependent granule-external membrane protein) is a leukocyte receptor of activated platelets that mediates cellular adhesion of platelets to neutrophils and monocytes. To identify the natural ligand on neutrophils and monocytes that interacts with PADGEM, we have evaluated anti-leukocyte antibodies for their ability to block leukocyte-PADGEM binding. Only anti-CD15 antibodies were able to inhibit the binding of neutrophils, monocytes, HL60 cells, and U937 cells to platelets. Anti-CD15 antibodies inhibited the binding of U937 cells to PADGEM-expressing COS cells and to purified PADGEM incorporated into phospholipid vesicles. The CD15 antigen, lacto-N-fucopentaose III (Gal beta 1----4[Fuc alpha 1----3]NAcGlc beta 1----3Gal-beta 1----4Glc), inhibited the interaction of neutrophils or HL60 cells with platelets, whereas lacto-N-fucopentaose I did not; lacto-N-fucopentaose II demonstrated minimal inhibition. Lacto-N-fucopentaose III, and to a lesser extent lacto-N-fucopentaose II, but not lacto-N-fucopentaose I, inhibited the interaction of HL60 cells with COS cells transfected with PADGEM cDNA. CD15, lacto-N-fucopentaose III or Lex, is a component of the PADGEM ligand on neutrophils and monocytes.

The expression of Lewis(a) and Lewis(b) antigens reflects changes in fucosylation between normal and neoplastic cervical squamous epithelium

Antibodies against the carbohydrate antigens Lewisa (Lea) and Lewisb (Leb) allow further investigation into the changes in fucosylation of the glycocalyx occurring during the normal and neoplastic development of cervical squamous epithelium. Lea and Leb are expressed on a broad zone of suprabasal cells in normal cervical squamous mucosa often independent of individual Lewis gene and secretor status. A proportion of Lea is expressed in sialylated form. In cervical intraepithelial neoplasia, the progressive dedifferentiation of the squamous mucosa is mirrored by loss of both Lea and Leb expression. In invasive squamous carcinomas, Lea and Leb expression is seen only on cells in areas of differentiation. The expression of Lea and Leb in normal and neoplastic cervical squamous epithelium resembles that of the Lex antigen described by us previously. The structural similarity between these antigens is highlighted and evidence for a common functional role in maintaining the integrity of squamous mucosae is discussed.

Expression of the CD15 differentiation antigen (3-fucosyl-N-acetyl-lactosamine, LeX) on putative neutrophil adhesion molecules CR3 and NCA-160

The expression of the carbohydrate antigen 3-fucosyl-N-acetyl-lactosamine (CD15, LeX) on human neutrophil glycoproteins has been studied by immunoprecipitation and immunoblotting by using monoclonal antibody MC2. The antigen is expressed on membrane glycoproteins of approximate molecular mass 165 and 105 kDa. These glycoproteins include the complement receptor and adhesion molecule, CR3, in which the beta-chain (CD18, 105 kDa) shows much greater expression than the alpha-chain (CD11b, 165 kDa). Most of the 165 kDa CD15 antigen is accounted for by expression on the carcinoembryonic antigen (CEA)-related molecule NCA160. Other members of this family, NCA95, NCA90 and NCA55, which are also found in neutrophils, do not express the CD15 antigen. There is a marked increase in the surface expression of CD15, CR3 and the antigen recognized by anti-CEA antibodies upon activation of neutrophils by the chemotactic peptide N-formylmethionyl-leucylphenylalanine.

Characterization of human neutrophil glycoproteins expressing the CD15 differentiation antigen (3-fucosyl-N-acetyllactosamine)

The expression of the CD15 antigen, 3-fucosyl N-acetyllactosamine, on neutrophil glycoproteins has been studied by SDS gel electrophoresis and immunoblotting. The antigen is expressed on several glycoproteins, both intracellularly and on the cell surface. Each subcellular compartment appears to contain a specific antigen. A soluble, granule glycoprotein (Mr 80-90K) probably accounts for most of the intracellular staining detected immunohistochemically. Membrane glycoproteins of Mr, 85-90K and 25K are associated with granule membranes, the latter being an integral membrane protein. The CD15 antigen is expressed on several cell surface glycoproteins with Mr in the range of 165K and 105K. These antigens are also contained in an intracellular pool which is brought to the surface on activation of the cells with chemotactic peptides. The 165K and 105K antigens show identical electrophoretic mobility to two of the major glycoproteins detectable by PAS or protein staining of gels of detergent extracts of cell membranes. These glycoproteins include the complement receptor, CR3. The beta chain of CR3 (105K) and to a lesser extent the alpha chain (165K) express CD15; however, most of the CD15 antigen is associated with other glycoproteins of these molecular masses.