Changes in the expression of blood-group carbohydrates during oral mucosal development in human fetuses

Histo-Blood Group Antigens in Oral Cancer and Potentially Malignant Disorders

BACKGROUND

Early detection of oral cancer is of critical importance because survival rates markedly improve when oral lesions are identified at an early stage. Aim of the present study is to investigate the expression of ABO (H) antigens in tissue specimens of oral cancer and potentially malignant disorders and to determine the role of ABO (H) antigens in tumour staging.

MATERIALS AND METHODS

A prospective study was conducted on 60 cases of oral cancer and potentially malignant diseases. Specific red cell adherence test (SRCA-test) was used for studying A, B and O (H) antigens in tissue specimens and iso-antigenicity of epithelium was graded according to degree of adherence of indicator red blood cells.

RESULTS

Among OSMF group, grade II adherence was seen in 53.3% cases, grade III in 33.3% cases, grade IV in 13.3% cases. In leukoplakia group, grade II adherence was seen in 26.7% cases, grade III adherence in 53.3% cases, grade IV adherence in 20% cases. Within the leukoplakia group, cases with dysplasia showed decreased adherence, compared with cases without dysplasia. Oral cancer group, negative adherence was seen in 13.3% cases, grade I adherence in 46.7% cases, grade II in 40% cases. In oral cancer group, antigen reactivity was less in poorly and moderately differentiated carcinoma, compared to well differentiated carcinoma.

CONCLUSIONS

Antigen adherence and degree of loss of ABO (H) antigens in tissue specimens can be used for staging of the tumour.

ABO blood group antigens in oral mucosa. What is new?

Histo-blood group ABH (O) antigens are major alloantigens in humans. These antigens are widely distributed in human tissues and undergo changes in expression during cellular differentiation and malignant development. The ABH antigens have been characterized as terminal disaccharide determinants which represent secondary gene products. They are synthesized in a stepwise fashion from a precursor by the action of different glycosyltransferases. In non-keratinized oral mucosa, a sequential elongation of the carbohydrates is associated with differentiation of epithelial cells, resulting in expression of precursors on basal cells and A/B antigens on spinous cells. Reduction or complete deletion of A/B antigen expression in oral carcinomas has been reported, a phenotypic change that is correlated with invasive and metastatic potential of the tumours and with the mortality rates of the patients. Disappearance of the antigens is ascribed to the absence of A or B transferase gene expression. Several studies have shown that loss of A and B antigen expression is associated with increased cell motility, invasion in matrigel, and tumourigenecity in syngenic animals. In vivo studies of human oral wound healing show similarly decreased expression of A/B antigens on migrating epithelial cells. Some studies suggest that the relationship between expression of blood group antigens and cell motility can be explained by different degrees of glycosylation of integrins. Changes in ABO expression in tumours have, in some cases, been due to the A/B gene promoter, although little is known about the regulation of A, and B expression, in normal tissue.

The histo-blood group ABO system and tissue transplantation

In general, one might expect that ABO incompatibility of donor and recipient would be important to some degree if viability of the transplanted allograft is important for graft incorporation and function. This is true for some recipients of organs. However, ABO incompatibility appears to play a minor role, if any, in the clinical success of viable cornea and viable skin allografts. Even though A and B antigens may be present on the transplanted tissue, other factors that can contribute include the strength of the immune response, the avidity of the antibody, and the dose of the antigen presented, which may vary from donor to donor. Although A and B antigens are present on endothelium, the use of ABO-incompatible heart valves is successful, as they carry out their mechanical function by using the strength of the connective tissue rather than the viability of the donor endothelium. The presence, immunogenicity, and significance of A and B antigens in human vessel transplants have not been well studied. With the more commonly transplanted tissue, such as bone and tendon, posttransplant success does not depend on cellular viability or ABO compatibility.

Expression of A antigens on erythrocytes of weak blood group A subgroups

Scanning immune electron microscopy using a monoclonal anti-A antibody which reacts with all type A oligosaccharide chains revealed A antigens on less than 5% of Am and Ael cells, some of which showed extremely strong labelling. This explains why Am and Ael cells can absorb significant amounts of anti-A without being agglutinated. A3 may be a heterogeneous subgroup, since A antigens were found on 82 and 58%, respectively, of the cells of 2 A3 individuals. A antigens were found on 75% or more of Ax cells. In many weak A individuals A-positive cells are apparently best detected if an anti-A is used which reacts strongly with other A oligosaccharide chains than type 2. From hyperimmune pregnancy sera Ax, Am and Ael erythrocytes absorbed antibodies which seemed to have other fine specificities than those absorbed by A2 cells. We conclude that weak subgroups of A may deviate from A2 both by number of erythrocytes expressing A antigens and the biochemical nature of the antigens.

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

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

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

Two monoclonal antibodies, HH8 and HH9, have been established after immunization of mice with galactosyl-A glycolipid antigen having the terminal structure, Gal beta 1----3GalNAc alpha 1----3[Fuc alpha 1----2]Gal beta 1----R, which is the precursor for type 3 chain A (repetitive A) and type 3 chain H (A-associated H). Both antibodies react strongly and specifically with galactosyl-A, but HH8 (IgM) showed strong hemagglutination of blood group A1, A2, O and B erythrocytes after sialidase treatment, while HH9 (IgG1) did not react with human erythrocytes even after sialidase treatment. HH8 and anti-T antibody, but not HH9, reacted with glycophorin A after sialidase treatment. The reactivity of HH8 with glycophorin A was abolished by beta-galactosidase and was inhibited by liposomes containing galactosyl-A, but not other glycolipids. In addition, anti-T antibody and peanut lectin reacted specifically with galactosyl-A glycolipids. These findings indicate that HH8 recognizes the terminal disaccharide Gal beta 1----3GalNAc alpha 1----R, which is the same sequence as the classically known Thomsen-Friedenreich antigen (T-antigen), whereas HH9 does not cross-react with T-antigen but recognizes the entire galactosyl-A structure. The T-antigen was also demonstrated by immunohistology with HH8 after neuraminidase treatment in a subset of cells in stratified epithelium.

Morphogenesis and malformations of the skin NICHD/NIADDK research workshop

Developmentally caused skin malformations constitute a spectrum of birth defects, some of which can be recognized prenatally by morphologic or biochemical means. The number of prenatally diagnosable skin diseases could be greatly expanded with an increased understanding of the molecular and cellular bases of skin development and the mechanisms that result in the generation of skin defects. The National Institute of Child Health and Human Development and the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases, therefore, sponsored a workshop that recommended basic biologic studies combined with clinical investigations of normal and abnormal cutaneous development set forth in this article. Investigations resulting from these research recommendations are intended to contribute to the knowledge that should aid in the prevention of developmentally caused skin deformities.

Current ideas on the significance of protein glycosylation

Carbohydrate has been removed from a number of glycoproteins without major effect on the structure or enzyme activity of the protein. Thus carbohydrate has been suggested to underly a non-primary function for proteins, such as in relatively non-specific interactions with other carbohydrates or macromolecules, stabilization of protein conformation, or protection from proteolysis. This non-specific concept is consistent with both the general similarity in carbohydrate structure on very diverse glycoproteins and the frequent structural microheterogeneity of carbohydrate chains at given sites. The concept is supported in a general sense by the viability of cells whose glycosylation processes have been globally disrupted by mutation or pharmacological inhibitors. In contrast to the above observations, other studies have revealed the existence of specific, selective receptors for discrete oligosaccharide structures on glycoproteins which seem to be important for compartmentalization of the glycoprotein, or the positioning of cells on which the glycoprotein is concentrated. Sometimes multivalency in the carbohydrate-receptor interaction is crucial. There are additional possible roles for carbohydrate in the transduction of information upon binding to a receptor. The possibility of specific roles for carbohydrate is supported by the existence of numerous unique carbohydrate structures, many of which have been detected as glycoantigens by monoclonal antibodies, with unique distributions in developing and differentiated cells. This article attempts to summarize and rationalize the contradictory results. It appears that in general carbohydrate does in fact underlie only roles secondary to a protein's primary function. These secondary roles are simple non-specific ones of protection and stabilization, but often also satisfy the more sophisticated needs of spatial position control and compartmentalization in multicellular eukaryotic organisms. It is suggested that there are advantages, evolutionarily speaking, for the shared use of carbohydrate for non-specific roles and for specific roles primarily as luxury functions to be executed during the processes of cell differentiation and morphogenesis.

Cell surface carbohydrate changes during embryonic and fetal skin development

Monoclonal antibodies to four type 2 chain carbohydrate antigens were used for immunohistochemical studies of embryonic and fetal skin. The antibodies detected N-acetyllactosamine and 3 fucosyl substitutes of this, blood group antigen H, Lex, and Ley. Periderm consistently stained for N-acetyllactosamine, Lex and Ley. The H antigen showed a variable and weak expression on peridermal cells from day 57 to day 84 estimated gestation age (EGA). After this period the H antigen was no longer expressed at peridermal cells. In the epidermis, N-acetyllactosamine was present on all cells until the age of 15 weeks EGA. After this period N-acetyllactosamine could only be demonstrated on basal cells after treatment with neuraminidase, indicating a masking of N-acetyllactosamine by sialic acid. The H antigen could not be demonstrated in the epithelium before 14 weeks EGA. At this time it appeared on spinous and granular cells in the epithelium. Lex stained both basal cells and intermediate cells positively, until keratinization around week 20 EGA. Ley is never expressed on basal cells. It is weakly expressed by intermediate cells from week 14 EGA. Our study demonstrates that N-acetyllactosamine is maximally expressed at the early stages of development, but may later be modified either by sialylation or fucosylation into blood group H or Lex, or by Ley substances, respectively. The orderly and well-defined changes observed during skin differentiation are in agreement with other studies, which have demonstrated the existence of chemically defined cell surface changes accompanying cell differentiation.

Immunohistologic expression of blood-group antigens in normal human gastrointestinal tract and colonic carcinoma

A panel of 7 mouse monoclonal antibodies and the lectin from Ulex europeus, detecting blood-group-related antigens of the ABH and Lewis systems, have been used to define the distribution of these antigenic structures within the human gastrointestinal tract, and to characterize their expression and modulation in colorectal carcinomas. The reagents employed detect the following blood-group specificities: A (all variants), B, H (type 2), Lewisa, Lewisb, X (Lewisx), Y (Lewisy) and type 1 precursor chain. Immunohistochemical studies demonstrate that these antigens are differentially expressed in various cell types and developmental stages of the human gastrointestinal tract. ABH expression undergoes developmental modulation in the human colorectal tract from positive to negative during embryogenesis, and is lost in adult cells. Colorectal tumors exhibit neosynthesis of ABH specificities that appear in tumor cells, and accumulation of the precursor antigens. They also show increased expression of Lewis antigens, especially Y determinant, which has a restricted pattern of distribution in normal tissues and is not found in normal colonic mucosa. Enhancement of the Lewis antigens is observed in all colorectal tumors analyzed, regardless of blood-group type and secretory status of the individuals studied. Tumor modulation of these antigens may be related to activation of suppressed genes and enhancement of fucosyltransferases.

Distribution of type 1 and 2 blood group chains in normal and pathological odontogenic epithelium defined by monoclonal antibodies specific for Lea and H type 2

This study describes the distribution of type 1 and type 2 blood group carbohydrate chains in human normal and pathological odontogenic epithelia and in epithelia of human oral mucosa. Odontogenic epithelium was examined from 12 fetal tooth germs, 25 ameloblastomas, 13 odontogenic keratocysts, 13 follicular cysts and 13 radicular cysts. Oral mucosal epithelia was studied from 12 fetuses and 10 adults. Cell surface carbohydrates were detected using antibodies with reactivity for the blood group antigens A, B, type 1 chain Lea and type 2 chain H by an immunofluorescence technique. The expression of Lea and H type 2 chain in fetal palatal epithelium and only H type 2 chain in adult palatal epithelium suggests that a change in synthesis of blood group chains occurs during development. Type 2 blood group chains (antigen H) were found in fetal tooth germs, type 1 (Lea) in ameloblastomas and both type 1 and type 2 in odontogenic cysts. These results indicate that a modulation in synthesis of blood group carbohydrates has occurred in ameloblastomas and odontogenic cysts as compared with the cells from which the lesions presumably are developed. It is suggested that ameloblastomas may be distinguished from odontogenic cysts by the inability of ameloblastomas to synthesize type 2 blood group chains and antigens A and B.

Relation of blood group carbohydrates to differentiation patterns of normal and pathological odontogenic epithelium

The distribution of epithelial cell surface antigens was studied in normal odontogenic epithelium from 20 fetuses and in odontogenic epithelium from 15 ameloblastomas, 16 odontogenic keratocysts, 15 follicular and 15 radicular cysts. The cell surface carbohydrates were detected using antibodies with reactivity for the blood group antigens A, B, H type 2 (A and B precursor) and N-acetyllactosamine (N-lac, H type 2 precursor) by an immunofluorescence technique. The expression of the blood group carbohydrates differed considerably in normal fetal odontogenic epithelium from that in ameloblastomas and odontogenic cysts. The A, B and H type 2 antigens were demonstrated in odontogenic keratocysts and in follicular and radicular cysts. Expression of the blood group carbohydrates was similar in follicular and radicular cysts but differed from that seen in odontogenic keratocysts by the failure to detect N-lac in the latter. The antigens A, B, H type 2 and N-lac were not expressed in any of the ameloblastomas including types with palisading of basal cells and polarization of basal cell nuclei and types with a plexiform pattern with cuboidal or polyhedral shaped peripheral cells. The findings indicate that epithelium of ameloblastomas can be distinguished from odontogenic cyst epithelium by differences in expression of cell surface carbohydrates with blood group specificity.