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C Stähli

Publications and source records attributed to C Stähli.

At least 19 recordsLinked to original sources
PubMed1988

Mucin-like carcinoma-associated antigen defined by three monoclonal antibodies against different epitopes.

Three monoclonal antibodies [MAb], b-8, b-12, and b-15, have previously been shown to react with mammary carcinomas and with a restricted set of cells in normal human tissues [C. Stähli et al., Experientia (Basel), 41: 1377-1381, 1985; H. R. Zenklusen et al., Virchows Arch. Abt. A Pathol. Anat., 413: 3-10, 1988]. They are shown here to recognize the same high molecular weight acid soluble glycoprotein antigen. Lectin binding, biolabeling, and deglycosylation experiments demonstrate that it contains O-linked carbohydrate side chains with sialic acid and hexoses including fucose, galactose, and/or galactosamine but little if any mannose. These properties, typical of mucin-like glycoproteins, agree with the antigen expression on mucin-secreting epithelial surfaces (H. R. Zenklusen et al., Virchows Arch. Abt. A Pathol. Anat., 413:3-10, 1988). The antigen is thus named mucin-like carcinoma-associated antigen (MCA). The three MAb are shown to bind to three different epitopes on MCA. Two of these epitopes (MCA-b-8 and MCA-b-15) are O-linked carbohydrates, and one (MCA-b-15) contains sialic acid. The epitope MCA-b-12 is of peptide nature. Of various two-site sandwich enzyme immunoassays composed of different combinations of the three MAb, the one with MAb b-12 in both positions is selected for a serum assay. Analyses of tumor patients' sera demonstrate that this MCA enzyme immunoassay can be of use as a tumor marker assay for mammary carcinomas. The parameter MCA enzyme immunoassay is shown to differ from other parameters described in the literature.

Antibodies, Monoclonal↗
PubMed1988

The immunohistochemical reactivity of a new anti-epithelial monoclonal antibody (MAb b-12) against breast carcinoma and other normal and neoplastic human tissues.

A mouse monoclonal antibody, MAb b-12, has been described previously (Stähli et al. 1985) which reacts with a Mr 350 kD glycoprotein with mucin-like characteristics (Stähli et al. 1987) expressed in cytoplasm and on the surface of human breast carcinoma cell lines (MCF-7 and ZR-75-1). In the present report the immunohistochemical reactivity of this MAb with normal and malignant human tissues is analyzed. Pre-experiments showed that the epitope b-12 is resistant to formalin treatment allowing the use of tissue processed by standard paraffin embedding methods. 167 normal and 408 neoplastic tissues were tested by indirect immunofluorescence or the avidin-biotin complex method. MAb b-12 stained the apical cytoplasm of secretory epithelia and their secretions including the acinar and ductular epithelia of the breast. It reacted with all breast carcinomas independent of their histological type or stage, frequently with all but in some cases with a fraction of the tumour cells. Some other carcinomas, primarily those of adenomatous differentiation, were also reactive. In these, however, the fraction of positive tumour cells was usually lower. The b-12 epitope is thus a marker for normal and neoplastic epithelia with secretory functions, particularly for breast carcinomas of all histological types and stages, and perhaps a differentiation marker for abortive adenomatous differentiation in solid carcinomas of the gastro-intestinal, uro-genital or respiratory tract.

Antibodies, Monoclonal↗
PubMed1988

Biochemical characterization of a tumor-associated vertebrate lectin, recognized by activated macrophages.

Activated macrophages, that display alpha-linked galactopyranosyl residues on their surface, and affinity adsorbents prepared by the covalent coupling of galactopyranoside to agarose, both adsorb two polypeptides from detergent extracts of all tumor cell lines tested. The larger polypeptide, Mr 100,000 is a cell surface component as judged by its availability to lactoperoxidase catalysed cell surface iodination. This polypeptide was found to be non-covalently associated with a smaller polypeptide, Mr 60,000, present on the inner face of the plasma membrane. Molecules with identical molecular sizes were also found to adsorb to activated macrophages from detergent extracts of chicken embryo cell membranes, suggesting an oncofetal nature for these proteins. Activated macrophages, and affinity adsorbents prepared by the covalent coupling of galactopyranoside to agarose, also bind the plant lectin, isolectin B4, prepared from the seeds of Griffonia simplicifolia. Based on these findings, we put forth the hypothesis that macromolecules of the same specificity, that is affinity to galactopyranosyl residues, must show homologies in their binding sites. We have predicted, therefore, that antisera prepared against the plant lectin, GSI-B4(1), should cross-react with galactopyranosyl-binding vertebrate lectins present on the surface of tumor cells. We were able to generate a number of hybridomas that produce antibodies reactive with both the plant and vertebrate lectins. Inhibition experiments, employing various mono- and disaccharides, suggest that the specificities of these antibodies are for determinants intimately associated with the galactosyl binding site on the lectin molecule. These antibodies were found to have moderate selectivity for tumor cells when tested in an immunohistochemical procedure using fresh-frozen or paraffin embedded sections of human biopsy material.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Identification of the conserved, conformation-dependent cytokeratin epitope recognized by monoclonal antibody (lu-5).

The epitope recognized by the murine monoclonal antibody (mAB lu-5) recently described as a formaldehyde-resistant, "pan-epithelial marker" of great value in tumour diagnosis is located on the surface of cytokeratin filaments. It has been preserved during vertebrate evolution from amphibia to man. As this epitope is not reactive after SDS-polyacrylamide gel electrophoresis (SDS-PAGE), the epitope-bearing protein has been identified by a dot-blot antibody binding assay, using purified proteins in which the epitope is reconstituted. We show that the epitope is present in most cytokeratin polypeptides of both the acidic (type I) and basic (type II) subfamily but does not occur in other cytoskeletal proteins. The location of this widespread epitope is discussed with respect to homologies of amino acid sequences of cytokeratins and their conformations.

Antibodies, Monoclonal↗
PubMed1985

Monoclonal antibodies against antigens on breast cancer cells.

Of 360 mAb obtained in a cell fusion experiment with the spleen cells of a mouse immunized with a mixture of different human breast carcinoma cell lines, 30 mAb were selected which reacted more strongly with tumor cells than with (noncancerous) fibroblasts. These mAb were tested for reactivity with additional types of cancerous and noncancerous tissues. Two mAb showed high tumor selectivity, but the corresponding epitopes on individual tumor cells were heterogeneously expressed. The mAb will be evaluated for in vivo applications.

Animals↗
PubMed1985

Immunohistochemical characterization of an anti-epithelial monoclonal antibody (mAB lu-5).

A mouse monoclonal antibody (mAB lu-5) was prepared using a lung cancer cell line as an antigen. The selected clone produces an IgG with a gamma-1 heavy chain and a kappa-light-chain. Immunohistochemical testing of mAB lu-5 on 117 normal tissue biopsies and 474 tumours revealed reactivity with an intracytoplasmic, formaldehyderesistant antigen present in most epithelial and mesothelial cells, but absent in mesenchymal cells. The antibody can therefore be used as a first order, pan-epithelial marker. It proved also useful for fast tumour diagnosis on frozen sections.

Animals↗
PubMed1985

Monoclonal antibodies reveal structural homogeneity of gamma-aminobutyric acid/benzodiazepine receptors in different brain areas.

Monoclonal antibodies (mAb) against a gamma-aminobutyric acid/benzodiazepine receptor complex (GABAA/BZR) were produced by using spleen cells from a mouse immunized with GABAA/BZR purified from bovine cerebral cortex. The mAb, most of which were of the IgG1 isotype could be divided into four groups (I-IV) specifying different antigenic structures. On immunoblots, group I mAb recognized exclusively the Mr 55,000 beta-subunit, while groups II and IV mAb recognized the Mr 50,000 alpha-subunit of bovine GABAA/BZR. Three of the four groups of mAb (I, III, and IV) crossreacted with both human and rat GABAA/BZR with the same subunit specificity as in bovine brain; the fourth group (II) crossreacted with human but not with the rat receptor. The binding sites for benzodiazepines as well as the high and low affinity GABA sites reside on the same structural complex as shown by immunoprecipitation. Ligand binding to these sites was not inhibited by mAb. Since quantitative immunoprecipitation of GABAA/BZR was achieved with mAb selective for either the alpha- or beta-subunit, both subunits occur in each individual receptor complex. The pattern of immunoblot staining suggests that the smaller alpha-subunit is not a processing product of the larger beta-subunit. Both alpha- and beta-subunits were present in all brain areas and species tested (rat cerebral cortex, cerebellum, and hippocampus; bovine cerebral cortex and cerebellum; human cerebral cortex). This suggests a uniform subunit composition of the receptor throughout the brain in contrast to earlier evidence for a heterogeneous subunit composition based on photoaffinity labeling.

Animals↗
PubMed1984

A rapid and highly sensitive solid-phase enzyme immunoassay specific for human fibronectin using a characterized monoclonal antibody.

A solid-phase enzyme immunoassay (EIA) was developed for the quantitation of human fibronectin in body fluids and cell culture media. In the assay a human fibronectin-specific murine monoclonal IgG1 (f-33) was used as capture antibody and polyclonal rabbit anti-fibronectin as detector antibody. The antibody showed no reactivity to purified monkey, dog, rabbit, horse, sheep, mouse, bovine or chicken fibronectins. The determinant of the monoclonal antibody was mapped to the cell-binding region of the fibronectin molecule. This localization was based on the use of purified fragments of fibronectin, immunoblotting, EIA and inhibition of fibroblast adhesion and spreading by the antibody. The detection limit of the fibronectin assay was 2 ng/ml. The assay was used for the quantitation of fibronectin in human plasma, urine and cerebrospinal fluid specimens and culture media of human cells.

Animals↗
PubMed1984

A GABA/benzodiazepine receptor complex from bovine brain: purification, reconstitution and immunological characterization.

A GABA/benzodiazepine receptor complex was purified from bovine cerebral cortex. The receptor fraction displayed binding sites for benzodiazepines as well as high and low affinity binding sites for GABA which are characteristics of the membrane-bound receptor. Two monoclonal antibodies of which one was directed against the 50 kd and the other against the 55 kd subunit were used for immunoprecipitation studies. Both of them were shown to quantitatively precipitate the entire receptor population. These results indicate that the binding sites for benzodiazepines and GABA (high and low affinity sites) reside on the same receptor complex containing a mixture of 50 kd and 55 kd subunits. Reconstitution of the receptor in phospholipid vesicles was achieved.

Animals↗
PubMed1984

The visualization of neuronal benzodiazepine receptors in the brain by autoradiography and immunohistochemistry.

Recent methodological improvements in receptor autoradiography have enabled the in vitro and in vivo binding of the benzodiazepines in the brain to be visualized and pharmacologically characterized with an anatomical resolution unattainable by biochemical radioligand binding assays. This approach, combined with computerized microdensitometry, can be used not only to map the distribution of benzodiazepine receptors in the brain but also to quantify their regional densities. Furthermore, immunohistochemical studies, using monoclonal antibodies directed against the solubilized and purified GABA/benzodiazepine receptor-ionophore complex, have revealed the distribution of antigenic sites on brain neurons and their processes. The brain regions of intense immunoreactivity are known to contain a high density of GABA-ergic efferents and neuronal-type benzodiazepine receptors. Current trends and prospects in this area of receptor research are briefly reviewed.

Animals↗
PubMed1983

Monoclonal antibody against the N-terminal end of human plasma fibronectin.

Purified human plasma fibronectin was digested with cathepsin G and the degradation products were tested for reactivity towards a monoclonal antibody. In an immunoblotting assay, after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the digestion products, the 85 000-Mr and 72 000-Mr gelatin- and heparin-binding fragments as well as the N-terminal 30 000-Mr heparin-binding fragment reacted with the antibody, whereas the 64 000-Mr gelatin- and heparin-binding fragment did not. In enzyme immunoassay the antibody reacted with intact fibronectin and the 30 000-Mr fragment but not with a 40 000-Mr gelatin-binding fragment. The alignment of the binding domains in these fragments and in the intact molecule [Vartio (1982) Eur. J. Biochem. 123, 223-233] localizes the antigenic determinant to the 21 000 Da N-terminal Staphylococcus aureus-binding region of fibronectin.

Antibodies, Monoclonal↗
PubMed1983

Evidence for preferential proteolytic cleavage of one of the two fibronectin subunits and for immunological localization of a site distinguishing them.

Purified plasma fibronectin was digested sequentially by thrombin and cathepsin G or by cathepsin G alone and the degradation products and their gelatin-binding and heparin-binding fractions were analyzed in NaDodSO4-polyacrylamide gel electrophoresis followed by immunoblotting with a defined monoclonal anti-fibronectin antibody. In early cathepsin G digests, several gelatin-binding fragments were detected: a few large (Mr greater than or equal to 150 000) polypeptides and fragments of Mr = 85 000, 72 000, 64 000 and 40 000. The 85 000-Mr and 64 000-Mr fragments appeared as closely spaced doublets and reacted with the antibody while the 72 000-Mr and 40 000-Mr fragments did not. Therefore the 64 000-Mr fragments are likely to be derived from the 85 000-Mr fragments. Three large fragments that bound to heparin, but not to gelatin were detected: Mr = 145 000, 135 000 and 120 000. Of these only the 135 000-Mr peptide reacted with the antibody. When fibronectin was digested with thrombin, polypeptides of Mr = 180 000-200 000 and a 30 000-Mr NH2-terminal fragment were produced. Cathepsin G added to this mixture further cleaved the fragments to a digestion pattern resembling that obtained from intact fibronectin except that the 85 000-Mr and 64 000-Mr fragments appeared as single bands and the amount of the 72 000-Mr fragment was reduced. The results suggest that thrombin cleaves the 30 000-Mr fragment preferentially from the NH2-terminal end of one of the two subunits of fibronectin and that the 85 000-Mr, 72 000-Mr and 64 000-Mr fragments obtained by the additional cathepsin G digestion were derived from the other chain. The results are consistent with the model that the antigenic determinant resides 72 000-85 000 Da from the NH2-terminus and is cleaved by cathepsin G alternatively at one of its sides. Thus, the components of the 85 000-Mr and 64 000-Mr doublets are derived from different subunits and the region located by the antibody may be responsible for the difference in their migration in the polyacrylamide gel.

Antibodies, Monoclonal↗
PubMed1983

Monoclonal antibodies to thymosin alpha 1.

Sixteen monoclonal antibodies specific for thymosin alpha 1 [Low et al., J. biol. Chem. 254, 981-986 (1979)] obtained from two fusions with the spleens of three mice [Stähli et al., Meth. Enzym. 92, 26-36 (1982b)] all react with an epitope in the C-terminal half of thymosin alpha 1. Human and foetal calf serum contain substances which cross-react with this epitope. A simple procedure to selectively remove the cross-reactive material and a sensitive RIA are described.

Animals↗