Isolation of a sulfated glycopeptidic antigen from human gastric tumors: its localization in normal and cancerous gastrointestinal tissues

Patterns of intestinal metaplasia in gastric biopsies. A comparison of different histochemical classifications

A total of 217 cases of gastric intestinal metaplasia (IM), out of 491 cases of consecutive multiple gastric biopsies, were examined using various histochemical methods. Three classifications were adopted (1) Jass and Filipe's (1979), (2) Segura and Montero's (1983), and (3) our own distinguishing two types of small intestine IM (incomplete and complete) and two types of colonic IM (incomplete and complete). Our classification revealed (1) a group of 'pure' IM cases (44%), (2) a group of 'combined' IM cases (15%), either small intestinal or colonic, expressing a maturating line, and (3) a conspicuous group of mixed 'mosaic' IM cases (41%) consisting of all possible combinations between the basic IM types. No significant correlations were found between each IM type and associated diseases (i.e. gastritis, stump gastritis, ulcer, adenoma and adenocarcinoma). However, a suggestive association between colonic IM and malignancy was observed. Our results confirmed the heterogeneity of IM and indicated two differentiation cell lines (ileal and colonic), thus providing additional evidence of impaired maturation and aberrant differentiation along various cell lines, supporting Leblond's (1976) unifying theory on the origin of intestinal epithelial cells.

Biochemical and immunological properties of the human carcinoma antigen CAR-5 defined by the monoclonal antibody BD-5

The monoclonal antibody (MAb) BD-5 reacts with an epitope (CAR-5) expressed in 83% of the gastric carcinomas and in 51% of the ductal pancreatic carcinomas. This MAb reacts also with epithelial cells of colorectal mucosa, but does not react at all with normal adult gastric mucosa or normal adult pancreas. We report the biochemical and immunochemical characterization of CAR-5-bearing molecule. The epitope was found to be carried on a mucin of more than 400 kDa with a density of 1.45 g/ml, metabolically labelled with 35S-sulfate, 3H-glucosamine, 3H-mannose and 35S-methionine. Antigenicity survived metaperiodate oxidation and alkalinization, while it was fully destroyed by pronase or papain. Trypsin, although cleaving the molecule, did not affect its antigenic activity. CAR-5 epitope is thus carried on the protein moiety of a sulfo-mucin. On the basis of its biochemical properties, the antigen was purified by a 3-step procedure, consisting of perchloric acid extraction, molecular sieving on Sepharose CL-4B and affinity chromatography on wheat-germ agglutinin coupled to Sepharose 4B. Cross-competition experiments, together with the chemical properties displayed by the different epitopes, clearly indicate that CAR-5 is different from all previously characterized carcinoma-associated determinants. Cross-DDIRMA experiments performed with different "catcher" and "tracer" antibody combinations showed that CAR-5 epitope may be expressed on the same mucin bearing CA 19-9, MOv2, DU-PAN-2, Lewisa and Lewisb epitopes.

Intestinal mucin antigens in ulcerative colitis and their relationship with malignancy

The expression of two intestinal mucin-associated antigens large intestine mucin antigen (LIMA) and small intestine mucin antigen (SIMA) were investigated by indirect immunoperoxidase staining of rectal mucosa from patients suffering from ulcerative colitis with (n = 6) and without (n = 31) associated carcinoma and in noncolitic controls (n = 40). The aim was to assess the relationship between antigen patterns and malignant change. SIMA, which is localised predominantly in the small intestine, is virtually undetectable in the normal adult colonic mucosa. However, this antigen is present in the foetal colon and colonic carcinoma. LIMA is expressed in normal colonic mucosa, but absent from the small intestine. LIMA staining patterns were not significantly different among the three groups. In contrast, expression of SIMA was significantly higher in the patients who had developed carcinoma (6/6) than in the noncancer group (7/71) (P less than 0.001). The presence of SIMA was also significantly related to areas of dysplasia compared to normal (P = .03) or inflammation (P less than .05), but it did not differ from mucosa showing "indefinite" atypia. The finding of 31% SIMA-positive biopsies associated with severe inflammation in colitis with active disease, but no evidence of malignancy, is difficult to explain at the present stage. A followup study would be necessary to determine its significance. Perhaps the most important finding is the increased frequency of SIMA-positive foci in histologically normal mucosa in carcinoma patients compared with the noncancer group (P less than .001), suggesting a field change. These observations may be prove useful for the identification of patients who may be at risk of developing carcinoma.

Histochemistry and electron microscopy in the diagnosis of small mucous cells in carcinoma of the stomach

One hundred and two cases of poorly differentiated adenocarcinoma were obtained from 71 surgical and 31 biopsy specimens of the stomach. These tumours produced both intracellular and extracellular mucins, which were demonstrated to be neutral mucins, N-acetyl sialomucins, sulphomucins and O-acetyl sialomucins. The majority of tumours (85.3%) secreted two or more kinds of mucins simultaneously, but only a small proportion (14.7%) produced a single kind of mucin. Ultrastructurally, three types of mucin granules were identified; these differed in shape and density. Tumour cells containing intracellular mucins or mucin granules were designated as mucous cancer cells and further subdivided into small, large and goblet mucous cells; tumour cells having neither mucins nor glandular differentiation were designated as undifferentiated cancer cells. These histochemical distinctions, supported by the electron microscopical observations, may be useful to demonstrate early malignant foci in gastric biopsies.

An immunohistochemical study of a colonic mucus antigen in normal and neoplastic gastrointestinal tissues

A monoclonal antibody YPC 44.3 which reacts with human large intestinal goblet cell mucus has been used to examine normal gastrointestinal mucosa and a series of gastric and colorectal carcinomas in an immunohistochemical study. In normal colonic mucosa the antibody is shown to detect an antigen which is expressed polymorphically and depends on the presence of the active allele at the Lewis locus for its expression. However the antigen appears distinct from regular Lewis antigens on the basis of immunoabsorption studies and organ distribution. Results of immunostaining tumours show no correlation with the site, classification or grade of tumour or the type of metaplasia adjacent to gastric cancers. The relationship of YPC 44.3 to other mucus antibodies and the importance of screening tissues with a wide range of blood group phenotypes is discussed.

Purification and characterization of a pancreas cancer-associated antigen from normal colonic mucosa

Pancreas cancer-associated antigen (PCAAc) was extracted, isolated and purified from human normal colonic mucosa. Purified PCAAc from normal colonic mucosa was homogeneous, as determined by polyacrylamide disc gel electrophoresis. The PCAAc had a molecular weight of approximately 600 000 and consisted of 30% carbohydrate and 70% protein. It had an isoelectric point of 4.4, and migrated to the alpha 2-beta region on immunoelectrophoresis. It was apparently different from other known gastrointestinal mucus antigens. Antiserum against purified PCAAc did not react with normal human serum, pancreas, liver, spleen or lung, but did react with ascites fluid from a patient with pancreatic cancer. PCAAc appears to be a mucus antigen that is associated with pancreatic cancer.

Differences in the expression of mucus-associated antigens between proximal and distal human colon adenocarcinomas

An immunohistological study showed differences in the expression of mucus-associated gastric M1 and intestinal M3 antigens between the proximal (100 cases) and distal (200 cases) colonic adenocarcinomas. Such a regional difference was not observed in the normal colon. A total of 55% and 78% of proximal tumours produced M1 and M3 antigens, respectively (versus 13% and 47% in the distal tumours). The high percentage of M1 positive proximal cancers could be explained by the higher percentage (i) of mucus-producing tumours, such as signet ring cell (6% vs 1%) or mucinous adenocarcinomas (29% vs 11%); and (ii) of M1(+) well-differentiated adenocarcinomas (45% vs 8.5%) and the presence of undifferentiated carcinoma producing M1 antigens (12% vs 0%). These latter carcinomas were found in older patients (mean age 78 years vs 66 years). These results suggest that, on the proximal side, the stem cells were more often engaged in a differentiation process involving the expression of M antigens than were those of the distal side. Moreover, the proximal stem cells more frequently produce a foetal differentiation program showing simultaneous expression of M3 and M1 antigens (in 48% of proximal tumours, vs 11.5% for the distal side). Around 12% of proximal adenocarcinomas (vs 2% of distal tumours) contained stem cells engaged in a cell differentiation program not observed in the normal adult or foetal colon, involving the predominant expression of M1 antigens associated with an undifferential histological pattern.

Incompatible blood-group A determinants in tumoral mucins. Isolation of oligosaccharides having a 2-acetamido-2-deoxy-alpha-D-galactopyranosyl group at the non-reducing end

Two glycopeptide fractions were obtained from pseudomyxomatous mucins secreted by an ovarian cystadenocarcinoma from a female having blood-group B, and by an appendix tumor from a male having blood-group O. The carbohydrate and amino acid content of these fractions suggests the presence of numerous carbohydrate side-chains linked through O-glycosyl bonds to a peptide core rich in threonine and proline. The two glycopeptide fractions exhibit compatible B- and H-blood-group activities. They are reactive towards Dolichos biflorus lectin and human anti-A agglutinins, and so exhibit an incompatible A activity. Alkali-borohydride degradation of Pronase-digested glycopeptides gave dialyzable oligosaccharides that were purified and shown to possess 2-acetamido-2-deoxygalactitol at the terminal reducing-end. 2-Acetamido-2-deoxyglucose, galactose, fucose, and neuraminic acid were absent, or present, in variable proportions. Four oligosaccharides containing 2-acetamido-2-deoxy-D-galactose residues were reactive towards Dolichos biflorus lectin and human anti-A agglutinins, indicating the presence, at the nonreducing end, of a 2-acetamido-2-deoxy-alpha-D-galactopyranosyl group, responsible for blood-group A activity.

Clinical aspects of gastrointestinal mucus

In such a bird's eye view of a very complicated and complex literature it is inevitable that significant contributions, particularly from earlier investigators, will have been overlooked. We have tried, however, to provide a reasonable framework for the many presentations and discussions which will take place at this conference. As in the past, it is evident that much needs to be done to reconcile the excellent histochemical studies of gastrointestinal mucus in many diseases with the increasing knowledge of mucin structure and composition. This will only be achieved by extraction of highly pure mucin from diseased bowel. In this regard, post mortem material provides an opportunity for mucin researchers which is not available to workers in other fields because of relative freedom from decomposition. The wedding of mucin technology with immunology is also a major priority. Immunoassay techniques provide the answer to quick and accurate product identification in secretion studies. Specific monoclonal antibodies will provide the route to structural differentiation of antigens in complex mixtures. It is also evident that we must seek to develop a variety of controllable models for the study of functional parameters of mucus in physiological conditions, parasite rejection, neoplasia and inflammatory states. Promising initiatives have been touched upon in this review, but these must only be the beginning. One must conclude, however, by recognizing that advances in knowledge have been truly remarkable since the last conference in 1976. One senses that some of the keys which will one day unlock the gates of this "ill-defined" kingdom are already in hand, while the remainder are at least within reach.

Intestinal M3 antigen, a marker for the intestinal-type differentiation of gastric carcinomas

The mucus-associated intestinal M3 antigen, normally restricted to intestinal goblet cells, was found in 35 out of 100 gastric adenocarcinomas belonging to intestinal (19/64) as well as diffuse (16/36) types according to Laurén's classification. often accompanying the other mucus-associated gastric M1 and M2 antigens. This M3 antigen was predominant over the gastric M antigens in 25 of these 35 tumors; 18 of these belonged to the histological intestinal type. According to the WHO classification, the M3 antigen was found to predominate in all mucinous adenocarcinomas (7/7), was never present in the undifferentiated carcinomas (0/8), but was also found in some tubulo-papillar (16/57) and signet-ring cell (12/27) adenocarcinomas. This antigen could be used as a new criterion and incorporated into a point system containing morphological and tumor cell behavioral considerations; then it would appear to be a good marker for intestinal-type differentiation. Indeed, 22 of these 25 gastric adenocarcinomas which produced predominantly M3 antigen showed such an intestinal-like differentiation. The M antigen pattern of gastric carcinoma suggested a duodenal rather than colonic-type differentiation.

Isolation and characterization of the native glycoprotein from pig small-intestinal mucus

Glycoprotein from pig small-intestinal mucus was isolated free of non-covalently bound protein and nucleic acid with a yield of over 60%. No non-covalently bound protein could be detected by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis or by equilibrium centrifugation in a density gradient of CsCl with 4 M-guanidinium chloride. The intrinsic viscosity and reduced viscosity of the glycoprotein preparations rose with the removal of non-covalently bound protein and nucleic acid from the glycoprotein, evidence that non-covalently bound protein does not contribute to the rheological properties of the glycoprotein in the mucus. The pure glycoprotein, in contrast with impure preparations, gelled at the same concentration of glycoprotein as that present in the gel in vivo. The glycoprotein was a single component, as judged by gel filtration and analytical ultracentrifugation. The distribution of sedimentation coefficients was polydisperse but unimodal with an s025,w of 14.5S and a molecular weight of 1.72 X 10(6). The chemical composition of the glycoprotein was 77% carbohydrate and 21% protein, 52% of which was serine, threonine and proline. The glycoprotein had a strong negative charge and contained 3.1% and 18.3% by weight ester sulphate and sialic acid respectively. The molar proportion of N-acetylgalactosamine was nearly twice that of any of the other sugars present, the glycoprotein had A and H blood-group activity and the average maximum length of the carbohydrate chains was deduced to be six to eight sugar residues.

Immunocytochemical studies of blood group A, H, I, and i antigens in gastric mucosae of infants with normal gastric histology and of patients with gastric carcinoma and chronic benign peptic ulceration

Indirect immunofluorescence studies of blood group A, H, I, and i antigens were performed on the gastric mucosae and tumor tissues of patients with gastric carcinoma, on the mucosae of patients with chronic benign gastric ulceration, and on the mucosae of infants who had died of causes other than gastrointestinal disease. The following findings were of particular interest: (1) Normal 'secretor' type mucosae were distinguishable from 'non-secretor' type mucosae by the uniform staining of the A or H antigens at the surface and in the pits. Normal 'non-secretor' type mucosae showed little staining of the H or A antigens but, instead, there was staining with anti-I(Ma) antibody. Staining with anti-I(Step) and anti-i(Den) did not show a clear correlation with the 'secretor'/'non-secretor' status of the normal mucosae. (2) Apparently normal areas of gastric mucosae of patients with gastric carcinoma or the normal part of gastric mucosae of patients with benign gastric ulcer frequently showed focal areas of loss or gain of the blood group antigens as is often seen in gastric carcinoma tissues. (3) In the mucosae of patients with intestinal metaplasia there was marked loss of A/H antigens in 'secretors' and I(Ma) antigen in 'non-secretors'. (4) Staining characteristics of tissues from gastric carcinoma were:(a) Focal loss of the expected A/H or I antigens was observed with much variation in staining from area to area, but only a minority showed complete loss of the expected staining. (b) A majority of the carcinomas from 'secretors' showed foci of substantial staining with anti-I(Ma) in contrast to normal 'secretor' mucosae. This is probably due to incomplete biosynthesis of A/H determinants. (c) Incompatible A-like staining by a rabbit anti-A serum was observed in one out of nine adenocarcinomas from blood group B or O persons. (d) A few cases showed substantial i antigen staining. The aberrant expression of blood group A, H, I, and i antigens in neoplastic as well as in some areas of morphologically normal mucosa of patients with benign and malignant diseases of the stomach is discussed in the context of current biochemical knowledge.

Products of gynaecological neoplasms: clinical and pathological applications

Alphafetoprotein is at present the only 'antigen' of proved clinical value in gynaecological neoplasia. Its synthesis and release by a particular type of germ cell tumour (yolk sac, endodermal sinus tumour) present alone or as part of a teratoma approaches many of the essential criteria of a utopian tumour marker. Unfortunately, none of the other recognised 'antigens' expressed and/or released by gynaecological tumours and which have been adequately assessed in the clinical situation, seem to represent laboratory adjuncts essential for adequate patient care at present. Further research is needed to define other factors if this approach to improving diagnosis and management is to succeed.

Antigens of gastric and intestinal mucous cells in human colonic tumours

Using immunofluorescence methods, 3 antisera respectively stain 3 groups of mucous cells of the human gastrointestinal tract, showing specific antigens for each group of cells. The antigens of the first group, the M1 antigens, were principally associated with columnar cells of the gastric epithelium, the M2 antigens with mucous cells of gastric and Brünner's glands, and the M3 antigen with the goblet cells of the intestinal mucosa. The gastric M antigens normally detectable in stomach and duodenum (but not in colon) were expressed in certain colonic tumours (benign or malignant) and in adjacent mucosa. They are always present with the intestinal M3 antigen. In 100 colonic adenocarcinomas, the intestinal M3 antigen was found in 53 cases, gastric M1 antigens in 29 cases, and gastric M2 antigens in 10 cases, always with the two other M antigens. A good correlation could be established between the association of M antigens and the histological type of tumour.

Another oncofoetal antigen in colonic carcinoma

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CEA and non-specific cross-reacting antigen (NCA) in medullary carcinomas of the thyroid

An immunohistological study of five cases of medullary carcinoma of the thyroid was undertaken with monospecific antisera against CEA and NCA. CEA was present in different areas of the tumors: cell cytoplasm, cell membrane at its apical pole when the tumor had a pseudoglandular organization, deposits in the lumen of pseudoglands, and peri- and extra-cellular deposits. From these extra-cellular deposits, CEA could easily reach the circulation, thus causing rising serum levels up to high values. NCA was found in the same tumors and in the same localizations.