PubMed Health⌕ Search

Biomedical subjects

W Dippold

Publications and source records attributed to W Dippold.

At least 55 records · Page 3Linked to original sources
PubMed1988

Antibodies to cell surface ganglioside GD3 perturb inductive epithelial-mesenchymal interactions.

Most epithelial sheets emerge during embryogenesis by a branching and growth of the epithelium. The surrounding mesenchyme is crucial for this process. We report that branching morphogenesis and the formation of a new epithelium from the mesenchyme in the embryonic kidney can be blocked by a monoclonal antibody reacting with a surface glycolipid, disialoganglioside GD3. In contrast, a more than 10-fold excess of antibodies to adhesive glycoproteins (N-CAM, L-CAM, fibronectin) fails to inhibit morphogenesis. Although the anti-GD3 antibody affected epithelial development, the disialoganglioside GD3 was expressed not in the epithelium, but in the mesenchyme surrounding the developing epithelia. The data raise the intriguing possibility that the anti-GD3 antibody inhibits epithelial development by interfering with epithelial-mesenchymal interactions.

Animals↗
PubMed1987

An amplification unit in human melanoma cells showing partial homology with sequences of human papillomavirus type 9 and with nuclear antigen 1 of the Epstein-Barr virus.

By partial homology with the DNA of human papillomavirus type 9 a cellular amplification unit was detected which is amplified in melanoma cells but not in Epstein-Barr virus-transformed B cells of two melanoma patients. A 2.4-kilobase EcoRI fragment of this amplification unit was cloned and designated mel/HPV9. At the chromosomal level we detected mel/HPV9 in homogeneously staining regions or in abnormally banded regions containing different marker chromosomes of both melanoma cell lines. DNA sequence analysis of a part of mel/HPV 9 revealed homology with the third internal repeat array of Epstein-Barr virus nuclear antigen 1.

Antigens, Surface↗
PubMed1987

Modulation of melanoma-associated antigens by monoclonal antibodies as visualized by radioimmunoelectron microscopy and radioantibody binding assay.

There is a wealth of information about monoclonal antibody (MAb) specificity and function on fixed tissues, yet little is known about formation and release of antigen-antibody complexes and their functional behavior in vivo. We analyzed the pathway of radiolabeled MAbs directed against melanoma-associated antigens by radioimmunoelectron microscopy (RIEM) on metabolically active cells of the melanoma cell lines SK-MEL-28, MeWo and Colo 38 at different time intervals. In parallel, binding and release of MAbs were investigated by the radioantibody binding assay (RBA). Both procedures gave essentially concordant results. Preferentially stable binding of immune complexes (ICs) to the cell surface after 30 and 120 min was shown for the MAb L10. Internalization was demonstrated for the MAb M.2.9.4. At the ultrastructural level, direct evidence of this phenomenon was obtained by visualization of radioactivity within the cytoplasm after 120 min. In the RBA this process was indicated by resistance of bound MAbs to acid buffer desorption. RIEM pointed to different transport mechanisms: constitutive internalization by endocytotic vesicles, or receptor-mediated endocytosis by coated vesicles. Shedding was indicated for the MAb R24 by release of the ICs from the cell membrane. It was demonstrated that stable fixation of ICs on the cell surface or modulation by internalization led to high accumulation rates, while shedding of antigen-antibody complexes resulted in a low accumulation of the MAb in tumor cells. Assuming that the potential of MAbs for clinical application is determined by the biological behavior of antigen-antibody complexes, these methods are suitable for demonstration of antigenic modulation by MAbs and eventually enable us to predict the localization, penetration and distribution pattern of individual MAbs in the melanoma patient.

Antibodies, Monoclonal↗
PubMed1987

Liver cell damage caused by monoclonal antibody against an organ-specific membrane antigen in vivo and in vitro.

Monoclonal antibodies have been raised against different antigenic determinants of normal rabbit hepatocytes. One antibody (2D3) recognized a liver-specific 43 kDa protein displayed exclusively on the basolateral portion of the hepatocellular membrane. Purified monoclonal antibodies were injected intravenously into rabbits. Following the injection of antibody 2D3, a dose-dependent increase of liver enzyme activities in sera was observed. Within 8 h, marked morphological alterations of the hepatocytes, including multiple cell necroses, could be demonstrated by light and electron microscopy. When isolated vital rabbit hepatocytes in culture were used as targets, cytotoxic effects of this antibody could also be observed. This indicates that liver cell damage was not due to antibody-dependent cellular cytotoxicity, but was mediated by the antibody itself. Control antibodies did not show these effects. Thus, our results clearly demonstrate that humoral immune reactions against particular liver membrane antigens may play a role in the development of liver diseases, and provide a useful experimental approach for the investigation of their specificity.

Animals↗
PubMed1987

Analysis of liver-specific protein LSP using murine monoclonal antibodies.

We describe twenty murine monoclonal antibodies directed against different antigenic determinants of human and rabbit liver-specific protein LSP. Among them, nine were directed against liver-specific epitopes as judged from immunohistological studies. Immunoelectronmicroscopy revealed that seven of these monoclonals recognized membrane determinants differing in staining of distinct areas of the hepatocellular surface. Eleven antibodies were directed against intracellular structures. Western blot analysis showed that the epitopes detected were displayed on either single or multiple protein bands with apparent molecular weights between 24,000 and 60,000. Further differences were observed with respect to the species specificity and (among the non-organ-specific antibodies) pattern of tissue cross-reactivity. Our results demonstrate the presence of several liver-specific determinants and membrane components within LSP. There are, however, a very much greater number of non-organ-specific epitopes and numerous determinants displayed on intracellular structures. This emphasizes the remarkable heterogeneity of the antigen preparation named LSP and warrants the use of clearly defined antigens in further studies dealing with auto-immune phenomena in liver diseases.

Animals↗
PubMed1986

[Acute fatty liver of pregnancy. A case report of the differential diagnosis of pregnancy-associated liver diseases].

Acute fatty liver of pregnancy (AFLP) is a rare, but often fatal disorder in the third trimester of pregnancy. We report on a patient with AFLP complicated by acute hemorrhagic diathesis, who survived after early diagnosis and adequate treatment. On electronmicroscopy, the characteristic microvesicular fatty deposits in the centrolobular hepatocytes could be demonstrated.

Acute Disease↗
PubMed1985

Biliary adenocarcinoma. Characterisation of three new human tumor cell lines.

Three human cell lines from adenocarcinomas of the extrahepatic biliary tract were established in permanent tissue culture. Mz-ChA-1 and Mz-ChA-2 were cultured from mechanically dissociated gallbladder adenocarcinoma metastases and SK-ChA-1 was grown from malignant ascites of a patient with primary adenocarcinoma of the extrahepatic biliary tree. Cell doubling times in tissue culture are 3-4 days for Mz-ChA-1 and approximately 2 days for Mz-ChA-2 and SK-ChA-1. All three tumour cell lines were successfully transplanted to nude mice, inducing progressive tumour growth. Histologically, nude mouse tumours resembled the original adenocarcinomas. In vitro formation of gland-like structures were regularly seen in Mz-ChA-1 and Mz-ChA-2 but only occasionally in SK-ChA-1. All three cell lines formed contacts through interdigitating processes with desmosomes and junctional complexes. On scanning electron microscopy, an abundance of microvilli was seen at the cell surfaces. Chromosome analyses of all three tumour cell lines showed a wide range of numerical abnormalities and presence of marker chromosomes. Mz-ChA-1 appears to be highly differentiated with cells producing mucus. Mz-ChA-2 synthesizes components of complement C2, C3 and C5, while Mz-ChA-1 and SK-ChA-1 produce only C3 in detectable quantities. In addition, Mz-ChA-2 supernatants are positive for ferritin and alpha 1-fetoprotein, but not CEA; while Mz-ChA-1 and SK-ChA-1 produce only CEA. Supernatants of all three cell lines are positive for N-acetyl neuraminic acid (NANA), phosphohexoisomerase (PHI) and LDH, and negative for alpha 2-macroglobulin, alpha 1-anti-trypsin, gamma-GT, AP, coeruloplasmin, haptoglobin and albumin. A high cloning efficiency renders these new tumour cell lines suitable for continued studies on clonal heterogeneity in malignant tumours. The establishment of these cell lines in tissue culture facilitates further studies on the biology of upper gastrointestinal tract cancer in man.

Adenocarcinoma↗
PubMed1985

Recent advances in the morphology of myositis.

Myositis in man may be divided into infectious and non-infectious forms. The myopathologist more often deals with the latter forms which comprise dermatomyositis/polymyositis, inclusion body myositis, mixed connective tissue disease/collagenoses, and granulomatous myopathies. Modern morphological techniques as enzyme-histochemistry, electron microscopy, immunohistology, and morphometry are of different value in various forms of myositis, but are often indispensable techniques in up-to-date diagnostic work up of a myositis.

Dermatomyositis↗
PubMed1984

A monoclonal antibody directed against an organ-specific liver cell membrane antigen in rabbits.

We generated monoclonal antibodies after immunization of mice with rabbit liver-specific protein (LSP) preparations. One of these antibodies (2D3) showed an organ-specific and species-specific binding pattern as determined by immunohistological and ELISA techniques. Immunoelectron microscopy studies demonstrated that this antibody is bound exclusively to the liver cell membrane except in the region of the bile canaliculi. We further describe a simple ELISA technique for the detection of anti-LSP antibodies. Our study clearly demonstrates the presence of at least 1 organ-specific liver cell membrane antigen in rabbit LSP and shows antigenic differences between areas of the plasma membrane of hepatocytes.

Animals↗
PubMed1984

Target level blocking of T-cell cytotoxicity for human malignant melanoma by monoclonal antibodies.

Cytotoxic T lymphocytes (CTL) for autologous malignant melanoma in culture of a patient AV were induced by restimulation of PBL (peripheral blood leukocytes) with AV melanoma cells in vitro and subcultured in interleukin 2 (IL-2) conditioned media. Monoclonal antibodies detecting six antigenic systems on melanoma cell surfaces were tested for blocking activity on the effector function of subcultured cytolytic T lymphocytes for autologous melanoma cells. The monoclonal antibodies R24 (gamma 3), specific for the GD3 disialoganglioside on melanoma cell surfaces and I24 (gamma M), detecting a similar antigenic determinant, blocked autologous T lymphocytotoxicity for malignant melanoma cells on the target level. The effector function of alloantigen activated cytolytic T lymphocytes generated by coculture of allogeneic PBL with Epstein-Barr virus (EBV) transformed AV B lymphocytes, was blocked by monoclonal antibody R24 when tested against AV melanoma targets, but not when tested against AV B lymphocyte targets. It is concluded that blocking by mAb R24 occurs in this system as a nonspecific effect, unrelated to the specific target antigen recognition by cytotoxic T lymphocytes. Steric hindrance or antibody induced membrane changes may account for the blocking effect of monoclonal antibody R24.

Antibodies, Monoclonal↗
PubMed1984

Induction of DNA polymerase alpha and terminal deoxynucleotidyl transferase in the human lymphoblastoid cell line Molt-4 by the immunomodulator bestatin.

The influence of the immunomodulator bestatin on the expression of terminal deoxynucleotidyl transferase and of DNA polymerase alpha and beta in Molt-4 cells has been studied. Bestatin was found to stimulate cell growth within the range of 0.3-33 microM, while concentrations higher than 300 microM were inhibitory during an incubation period of 48 h. The cell surface bound microsomal leucine aminopeptidase (bestatin receptor) activity decreased gradually during incubation at concentrations of bestatin above 3 microM. This effect was also observed after incubation with amastatin, but not with leupeptin or tunicamycin. Determinations of the activities of DNA synthesizing enzymes from bestatin-treated Molt-4 cells revealed a direct correlation between the decrease of the surface bound microsomal leucine aminopeptidase activity and the increase of the terminal deoxynucleotidyl transferase and DNA polymerase alpha activity; the DNA polymerase beta activity remained unchanged. From these experiments it is hypothesized that bestatin might cause a promoting effect on the differentiation processes of precursor T cells in vivo.

Adjuvants, Immunologic↗
PubMed1983

[Candida meningitis. Case report].

Subacute meningitis caused by Candida albicans was confirmed by culture and immunoserologically in a 19-year-old girl. Combined administration of amphotericin B and flucytosine only slowly affected the course of the disease despite impressive improvement in clinical symptoms. Pleocytosis (1000/mm3) in cerebrospinal fluid persisted. Falling Candida antibody titre in serum and CSF, however, pointed to an improvement in the acute infection. Treatment had to be discontinued after 42 days because of side-effects such as rigor, fever and polyuria with low concentration. Under serial clinical observations with occasional CSF punctures complete cure occurred with normal CSF findings. There was an additional and unusual neurological-otological condition of intermittent inner-ear deafness, left more than right, before treatment. Recording of early auditory evoked potentials pointed to an involvement of the cranial nerves as part of the inflammatory process.

Adolescent↗
PubMed1980

Alloantigen-induced T-cell proliferation: Lyt phenotype of responding cells and blocking of proliferation by Lyt antisera.

Cytotoxic T cells of the mouse express Lyt-1 as well as Lyt-2 and -3 on their surface, and T-cell cytotoxicity can be blocked by Lyt-2 and Lyt-3 (but not Lyt-1) antisera in the absence of added complement [Nakayama, E., Shiku, H., Stockert, E., Oettgen, H. F. & Old, L. J. (1979) Proc. Natl. Acad. Sci. USA 76, 1977-1981]. This analysis has now been extended to the study of the Lyt phenotype of T cells responding to alloantigens, concanavalin A (Con A), and phytohemagglutinin (PHA) and the effect of Lyt antibody on T-cell proliferation and the generation of H-2-specific killer T cells. H-2 (D/K and I), Con A, and PHA stimulation was abolished by pretreating responding cell populations with Lyt-1 antiserum and complement. Pretreatment with Lyt-2 or -3 antiserum and complement did not decrease alloantigen or Con A stimulation but did abolish PHA stimulation. Cytotoxic cells were not generated in H-2 alloantigen-primed cultures pretreated with Lyt-1, -2, or -3 antiserum and complement. When responding cells were cultured with Lyt antiserum in the absence of added complement, Lyt-2 or -3 antiserum (but not Lyt-1 antiserum) blocked alloantigen-induced proliferation and delayed generation of killer cells. Under similar conditions, Con A and PHA stimulation was not blocked by Lyt-1,-2, or -3 antiserum. Evidence from these Lyt elimination and blocking tests and from direct Lyt phenotyping of responding cells leads to the following conclusions. Two populations of Lyt(+) cells are involved: Lyt-1(+)2(-)3(-) and Lyt-1(+)2(+)3(+). Current evidence does not favor the existence of Lyt-1(-)2(+)3(+) cells but indicates that pre-killer and killer cells derive from the Lyt-1(+)2(+)3(+) population and have a Lyt-1(+)2(+)3(+) phenotype. H-2 (D/K and I) and PHA stimulation ordinarily activate the Lyt-1(+)2(+)3(+) population, whereas Con A and I region or Mls locus antigens activate the Lyt-1(+)2(-)3(-) population. However, when Lyt-1(+)2(+)3(+) cells are eliminated or blocked by Lyt-2 or -3 antiserum, H-2 alloantigen stimulation leads to proliferation of the Lyt-1(+)2(-)3(-) population. Blocking of H-2-induced proliferation by Lyt-2 or -3 antiserum adds further support to the possibility that molecules bearing Lyt-2 and -3 determinants are involved in T-cell recognition.

Animals↗