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The Tn determinant (GalNAc alpha-O-Ser/Thr) is expressed by about 90% of human carcinomas, but is cryptic in most normal human tissues. A murine monoclonal antibody (MAb) 83D4, developed following immunization with human breast carcinoma cells, reacts with a Tn-related epitope. In the present study we characterized the glycoprotein antigen identified by 83D4 in the human breast carcinoma cell line MCF-7. We further showed that the 83D4 antigenic determinant is masked in human milk fat globule membranes (HMFGM), and can be exposed upon mild m-periodate treatment after desialylation. Western-blot analysis resolved the 83D4 antigen from MCF-7 into two main components of 120-190 kD and > 500 kD respectively. Non equilibrium pH gradient electrophoresis/SDS PAGE revealed the acidic nature of the reactive glycoproteins (pI 4.43-4.70). 83D4 antigenic activity resolved by CsCl gradient ultracentrifugation layered on a wide range of densities (1.30-1.46 g/ml) including typical densities of mucin-like glycoproteins but also lower densities. The amino acid composition of the antigen, relatively rich in serine but poor in threonine and proline, confirmed the divergence from other mucin-like carcinoma-associated glycoproteins. Dicarboxylic amino acids were abundant, accounting in part for the acidic nature of the molecules. ELISA and Western-blot analysis of the subcellular fractions from MCF-7 cells revealed that the 83D4 antigen is mainly contained in plasma membranes (85%) from which it may be resolved into two broad bands (slow and fast migrating components). These results provide information on a group of breast carcinoma associated glycoproteins related to but different from typical mucins, and provide data on alteration of O-glycosylation in tumor cells.

Monoclonal antibody (MoAb) 83D4 was generated by immunization with cell suspensions obtained from sections of formol-fixed paraffin embedded human breast cancer. It recognized an antigen expressed in breast carcinomas but not in normal breast tissue. Pleural and ascitic fluids from 66 patients were studied by an 83D4 heterologous sandwich radioimmunoassay (SRIA) using solid-phase immobilized wheat germ agglutinin to detect the 83D4 soluble antigen. Using a cutoff level of 5 units/ml of 83D4 antigen, higher values were found in 22 of 27 breast cancer-associated effusions (mean = 10.72 +/- 6.80 units/ml). The 20 nonmalignant effusion fluids tested showed lower values (mean = 1.16 +/- 1.49 units/ml, P less than 0.001). The antigen was undetectable or present in low levels in effusions from patients with hematologic malignancies. When SRIA results were compared with conventional cytologic diagnosis in breast-cancer effusions, elevated levels of 83D4 soluble antigen were found in all patients (8 of 8) in whom malignant cells had been detected, in 4 of 8 patients with the diagnosis of "suspected malignancy," and in 10 of 11 patients with negative cytologic findings. Using an immunoglucosidase method on cell smears of various origins, MoAb 83D4 stained metastatic cells of breast and ovary carcinomas but did not reactive with mesothelial cells and other normal or malignant cell types. These results suggest that quantitation of the 83D4 soluble antigen may be used to improve the diagnosis of cancer in serous effusions.

Immunocytochemical assays were performed on cell cultures as well as on a wide range of human tissues using a monoclonal antibody, MAb 83D4, produced by a murine hybridoma generated by immunization with a cell suspension from a paraffin block of human breast carcinoma tissue. Frozen breast tissue samples (n = 49) were compared to fixed and paraffin-embedded samples (n = 62). Paraffin sections (n = 194) from a variety of human tissues were compared to breast immunoreactivity. Immunoprecipitates, resulting from positive reactions between 83D4 and Avidin Biotin Peroxidase, were evaluated by computer-assisted microcytophotometry (SAMBA). In some frozen breast samples (n = 27), 83D4 antigen distribution was correlated with tumor cell DNA index, ploidy balance, growth fraction (Ki67), hormone receptor (ER, PR) antigenic sites, NORsAg and oncoprotein pHER-2/neu cell content. MAb 83D4 reacted with 3 breast cancer cells lines (MCF7, T47D and H466B) but not with normal epithelial breast cells in culture. The immunostaining in frozen paraffin sections from breast were similar. Like most normal tissues, normal breast did not react with 83D4. Cellular MAb 83D4 antigen concentration increases with the degree of malignancy but is independent of DNA nuclear content, ER, PR, growth fraction and pHER-2neu in cancers. These results suggested that routine immunohistochemical procedures using MAb 83D4 could facilitate the grading of breast cancer, in particular by allowing detection of microvascular invasions in the breast as well as at a distance and of blood-born micrometastases, especially in bone marrow.

Monoclonal antibody (mAb) 83D4 was generated using formol-fixed paraffin-embedded human breast carcinoma tissue as the immunogen. Previous studies demonstrated that it was reactive with breast carcinoma tissues, but not with normal breast. The antigen identified by mAb 83D4 was detected, using ELISA, in MCF7 breast carcinoma cell line membrane extracts, in primary breast and colon carcinoma tissue extracts and in pleural effusion fluid from patients with metastatic breast cancer. No reactivity with 83D4 was found in either human milk fat globule membranes or skimmed milk. 83D4 reactive antigen was found to be a heterogeneous high molecular weight (MW) protein (apparent Mr:300-400 to over 1000 kDa) by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The antigen was purified from MCF7 cells, breast and colon carcinomas and effusion fluid, by perchloric acid solubilisation followed by immunoaffinity chromatography with 83D4. The immunopurified antigen from MCF7 cells and pleural effusion fluid was further analysed by gel filtration and ion-exchange chromatography, which confirmed the high MW and indicated the charge heterogeneity of the reactive molecules. The 83D4 reactive antigen strongly bound to wheat-germ agglutinin and weakly to peanut lectin. No binding was found with lentil lectin or concanavalin A. Antigenic activity was strongly reduced by trypsin and subtilysin digestion and by treatment with sodium periodate, but it was not affected by neuraminidase. These results imply the glycoprotein nature of the 83D4-defined antigen and the involvement of carbohydrate, but probably not sialic acid, in the epitope. Purified 83D4 antigen did not display reactivity for mAb HMFG-1, directed against a polymorphic epithelial mucin, PEM, using ELISA, but bound mAb CC49 and weakly mAb B72.3, antibodies which define a tumour associated glycoprotein, TAG-72. Moreover CC49 and 83D4 showed similar reactivity pattern in immunoblotting assays. A double determinant radioimmunoassay confirmed that 83D4 antigen carries epitopes for mAb B72.3 and CC49. Competition radioimmunoassays clearly distinguished the 83D4 defined epitope from those recognised by B72.3 and CC49, demonstrating that antibody 83D4 identifies a unique epitope. It is suggested that the antigens identified by mAb 83D4 and by mAb B72.3 and CC49 may form part of the same family of carcinoma associated glycoproteins.

We have previously reported the production of monoclonal antibody (MAb) 1BE12, which recognizes a glycoprotein in breast-cancer cells. In the present work, 1BE12 reactivity was tested by immunohistochemistry in bladder carcinoma (92 cases) and in non-tumoral bladder samples (15 cases). In 71% of bladder tumors, more than 30% of cells were intensely stained by 1BE12. The percentage of reactive cells was higher in cancers invading the muscle than in more superficial tumors (p = 0.039). In non-tumoral bladder, immuno-staining, when present, was usually confined to the superficial layers with a low number of cells stained (less than 30%) in 13/15 cases. Slot blots, performed on urine samples from 43 bladder-cancer patients and 21 healthy controls, were quantified by densitometry scanning. We found higher optical density (OD) values in urine from muscle-invasive-cancer patients than in urine from more superficial tumors and healthy controls, with a significantly different distribution (p = 0.005). The urinary antigen was detected by immunoblotting with 1BE12 as high-molecular-weight species (greater than 150 kDa). The reactive glycoprotein could thus be purified by immunoaffinity and FPLC filtration from the perchloric-acid-soluble fraction of urine from patients with invasive bladder carcinoma. The availability of purified antigen will allow us to quantitate our assay, in order to evaluate its potential use as a prognostic indicator in bladder-cancer patients.

Spleen cells from inbred Biozzi mice, immunized against the human breast cancer cell line T47D, were fused with murine myeloma SP2O cells to generate monoclonal antibodies. One of these, 1BE12, of IgM isotype, reacted with five of six human breast tumor cell lines, while no binding was detectable with normal lymphocytes, RBC, or fibroblasts. The antigen recognized by monoclonal antibody 1BE12 was localized on the surface of T47D and MCF7 cells and was detected in cell-free supernatants of cultures. The antigen was found also on the surface of milk secretory cells. Immunohistochemical staining of frozen and paraffin-embedded sections of human tissues showed apical polarized reactivity in normal breast glands, while in all breast cancers staining was either cytoplasmic or membranous and heterogeneously distributed. Immunostaining was also observed in some other normal epithelia, including salivary gland, gastroduodenal mucosa, exocrine pancreas, and cervix. The antigen was not detectable in secretory endometrium, whereas proliferative endometrium was strongly stained. Colon carcinoma, and cancers of the bladder and endometrium were strongly reactive. No staining was detected in melanoma, lymphoma, mesothelioma, non-small cell lung carcinoma, and thyroid, renal, and ovarian carcinomas. Lectin absorption of MCF7 membrane extracts reduced 1BE12 binding. A large reduction in 1BE12 reactivity was observed after digestion of T47D and MCF7 membrane extracts with proteases. Treatment with sodium periodate resulted in complete loss of antigenicity, while neuraminidase treatment did not affect 1BE12 binding. These findings suggest that the 1BE12 epitope is expressed on the carbohydrate moiety of a glycoprotein and does not contain sialic acid. Immunoblotting of the perchloric acid-soluble fraction of MCF7 membrane extracts after electrophoresis in 1% agarose detected the antigen as a high molecular weight species (Mr greater than 900,000). The antigen was purified by perchloric acid extraction of MCF7 membrane preparations followed by affinity chromatography on 1BE12 antibody coupled to Sepharose-4B and gel exclusion fast protein liquid chromatography. No reactivity of the purified material was found with monoclonal antibodies directed against human milk fat globule membrane-associated mucins HMFG1 and DF3.

This report describes a method for the production of murine monoclonal antibodies (MAbs) against cellular antigens preserved during formol fixation and paraffin embedding of human tissues in an attempt to select markers that would be useful in immunopathology. Hybridomas were prepared using spleen cells from mice immunized with cell suspensions obtained from formalin-fixed paraffin block sections of a human breast carcinoma. A monoclonal antibody 83 D4 was selected, which was reactive with paraffin embedded breast carcinoma tissues, but not with normal breast. The reactive antigen has a high molecular weight (400-1000 kD) and was detected on the cell surface of live human breast cancer cell lines and on frozen tissues sections. These results demonstrate that the MAb 83 D4 identifies a native breast tumor associated epitope conserved during tissue fixation and embedding and could be used as an immunohistochemical marker.

Two mouse hybridomas, producing the monoclonal antibodies 7B10 and 1BE12 which react with membrane antigens of a metastatic human breast tumor cell line were selected. One of them, 7B10, is directed against a mammary gland antigenic determinant and selectively stain mammary carcinoma on histologic sections after fixation and paraffin embedding.

A monoclonal antibody (7B10) which displays differential reactivity with breast carcinomas compared to benign lesions or normal breast tissue was selected by fusion of spleen cells from BALB/c mice immunized with the T47D human mammary carcinoma cell line. The antigen, recognized by 7B10 on T47D cells, appeared to be both surface and cytoplasm localized, as demonstrated by indirect immunofluorescence, immunoperoxidase, and electron microscopy studies. This antibody (IgG1) bound with four human breast cancer cell lines (T47D, MCF7, ZR-75-1, and HSL53) which express estrogen receptors. No binding was observed with cancer cell lines of other origin or with normal cells. In vivo, by immunoperoxidase staining of frozen sections of normal breast, the antigen recognized by 7B10 appeared to be located on epithelial cell membranes, whereas in benign and malignant mammary disorders, staining also involved the cytoplasm, as confirmed by electron microscopy on fresh cancer tissue. On formalin-fixed, paraffin-embedded sections, cytoplasmic staining was detected in breast cancer, but no immunostaining was observed with benign lesions or normal breast. In paraffin sections, most normal tissues investigated did not react with 7B10 antibody. However, ducts in the parotid gland, tubules in the kidney and some biliary ducts, and apocrine glands in the skin showed irregular, diffuse weak staining. 7B10 was unreactive with adenocarcinomas of origin other than breast, except for some cells in ovarian clear cell carcinoma. No reactivity was observed with squamous carcinomas, lymphomas, or melanomas. The antigen recognized by 7B10 appeared to be a Mr 32,000 protein, as identified by immunoprecipitation from extracts of T47D after labeling with [35S]methionine. Since the antigen was present only on the membrane of differentiated normal mammary epithelial cells, and was also expressed in the cytoplasm of tumor cells, it may be of interest in immunological studies of mammary epithelial cell differentiation. Moreover, since in formalin-fixed tissues immunostaining is virtually confined to mammary carcinomas, monoclonal antibody 7B10 may have diagnostic applications in breast cancer.

Breast cancer is the most frequent cancer among women in western countries, where it represents about one third of tumors. Many laboratories utilized monoclonal antibodies technology for studying this pathology and for clinical applications. Different immunisation strategies have been utilized in the aim to produce monoclonal antibodies specific of mammary epithelial cells, of cancer cells or of cell secretions products. Despite efforts none of these are entirely specific, either for the normal tissue or for malignant tumors derived from it. However several of them had applications in fundamental study of oncogenesis and/or in tumor diagnostic, and in therapeutic assays. In this review we analysed described monoclonal antibodies, their reactive antigens and their applications.

Monoclonal antibody 7B10, raised against the human breast cancer cell line T47D, identifies an antigen found in human breast carcinomas and in normal breast. Western blot and immunoprecipitation studies detected a Mr 76,000 antigen in cytosol, cell membrane, and cell culture supernatants of T47D cells. 7B10 binding to T47D cell extracts was affected by proteolytic digestion with protease type VI, trypsin, and subtilisin while it was not altered by neuraminidase digestion. Adsorption of breast cancer cell line extracts with concanavalin A reduced 7B10 immunoreactivity more than 70%. These results suggest that the antigen is a glycoprotein and that the epitope does not contain sialic acid. 7B10 was reactive with neither human milk fat globule membrane, nor skimmed milk, nor the milk-derived HBL 100 cell line. Conversely binding was detected in more than 50% of normal breast epithelial cells in culture. 7B10 immunostaining was positive on frozen sections of normal breast and nonmalignant mastopathies in 30 to 90% cells. In frozen sections of other normal tissues, 7B10 immunoreactivity was detected only in colon, apocrine glands of skin, parotid ducts, and luteal phase endometrium, confirming previous data on paraffin sections. Strong, homogeneous immunostaining was observed on frozen sections of intraductal and invasive lobular breast carcinomas (100% of cases), while more heterogeneous staining was found on invasive ductal carcinomas. Colon and rectal carcinomas, one carcinoma of the esophagus, and some cells in serous ovarian carcinomas also showed 7B10 reactivity. Immunoblotting of the 7B10-immunoreactive fraction isolated by Sepharose CL-6B chromatography of a breast carcinoma tissue sample extract identified the Mr 76,000 antigen, which was also detected in several breast cancer specimens, in colon adenocarcinomas, and in serous ovarian carcinoma fresh tumor extracts. The Mr 76,000 glycoprotein described here represents a breast cancer-associated antigen previously undescribed, mainly expressed in normal breast and breast tumors.