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G Riethmüller

Publications and source records attributed to G Riethmüller.

At least 181 records · Page 10Linked to original sources
PubMed1987

Tumor progression in human malignant melanoma: five stages defined by their antigenic phenotypes.

The antigenic profile of melanocytic cells in the course of local and systemic tumor progression of human malignant melanoma was investigated by the reactivity of a panel of monoclonal antibodies (MAbs) in frozen sections of histologically defined melanocytic lesions. Specific antigenic phenotypes made it possible to distinguish 5 groups of lesions which could be ranked in relation to each other due to the sequential acquisition or loss of progression markers. On this basis, a scheme of antigenic changes which accompany the stepwise transformation of normal skin melanocytes into highly malignant metastatic melanoma cells is proposed. The steps of tumor progression identified solely by phenotyping with MAbs were in complete concordance with the concept of melanoma progression derived from histological, statistical and clinical analyses. Furthermore, our finding that the expression of gp89 as well as HLA-DR antigens can be induced by interferon-gamma in vitro provides evidence that immune interferon may play a role in the regulation of genes leading to phenotypic changes in progressing melanoma cells.

Animals↗
PubMed1987

The cellular receptor (CD4) of the human immunodeficiency virus is expressed on neurons and glial cells in human brain.

The expression of the CD4 antigen in normal human brain was investigated in parallel by immunohistochemical and Northern blot analyses. With anti-CD4 antibodies detecting different epitopes of the molecule, CD4+ neurons were defined in the cerebellum, thalamus, and pons. CD4+ glial cells were identified in the thalamus and pons. CD4-specific mRNA was detected in all three subareas and in the hippocampus, while other subareas were negative. The CD4+ cells were negative with anti-T cell antibodies (anti-CD2 and anti-CD8), as well as with antimonocyte antibodies (M-M 522 and M-M 42).

Antibodies, Monoclonal↗
PubMed1987

Discrimination between benign and malignant cells of melanocytic lineage by two novel antigens, a glycoprotein with a molecular weight of 113,000 and a protein with a molecular weight of 76,000.

The present study describes two novel antigens, a glycoprotein with a molecular weight of 113,000 and a protein with a molecular weight of 76,000, which are associated with the transformed phenotype of melanocytes. The monoclonal antibodies (MoAb) MUC18 and MUC54, raised against human malignant melanoma, were selected for differential reactivity with normal and neoplastic cells of melanocyte lineage. The antigen defined by MoAb MUC18 is a membrane bound monomeric sialylated glycoprotein with an apparent molecular weight of 113,000. In contrast to the broad reactivity with melanomas, isolated nevus nests were stained in only 1 of 55 nevi investigated. No staining of MoAb MUC18 was observed in a large variety of surgically removed normal and tumor tissues except for smooth muscle cells of the blood vessel wall and hair follicles. MoAb MUC54 immunoprecipitated a cytoplasmic monomeric protein with an apparent molecular weight of 76,000. By immunoperoxidase staining, the antigen was demonstrated on a large number of melanomas and in addition on 1 of 36 nevocellular, 3 of 4 Spitz, and 5 of 14 dysplastic nevi. The Mr 76,000 protein was found in a number of epithelial tissues and various types of neoplasms. Both antibodies presented in this study define structural changes in the antigenic profile of melanocytes occurring during carcinogenesis.

Antibodies, Monoclonal↗
PubMed1987

Micrometastatic cancer cells in bone marrow: in vitro detection with anti-cytokeratin and in vivo labeling with anti-17-1A monoclonal antibodies.

The detection of early micrometastasis or disseminated single tumor cells poses a problem for conventional diagnosis procedures. Using a panel of monoclonal antibodies against cytokeratin and the 17-1A epithelial antigen we identified immunocytochemically tumor cells in bone marrow of patients with breast cancer (n = 155) and colorectal cancer (n = 57) at the time of surgery of the primary tumor. Monoclonal antibody CK2, recognizing the human cytokeratin component 18 in simple epithelia, appeared to be the most suitable reagent because of its negative reaction with bone marrow samples of the noncarcinoma patients (n = 75). Its specificity was further demonstrated in a double-marker staining procedure using an anti-leukocyte common antigen monoclonal antibody (T200) as counterstain. A comparative analysis showed that immunocytology was clearly superior to conventional cytology (n = 212) and histology (n = 39). In 9.5-20.5% of patients without distant metastasis, tumor cells could be detected in bone marrow. We found a significant correlation between tumor cells in bone marrow and conventional risk factors, such as distant metastasis or lymph node involvement. In a first approach toward immunotherapy we demonstrated in 3 patients that infused monoclonal antibody 17-1A can label single tumor cells in bone marrow in vivo. We then used this approach to follow up 7 patients undergoing 17-1A therapy in an adjuvant clinical trial.

Antibodies, Monoclonal↗
PubMed1987

Monocyte phenotype and function in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related disorders.

The CD4 molecule, which is known to play an important role in the susceptibility of T lymphocytes to infection by the human immunodeficiency virus (HIV), is also expressed in small amounts on the surface of monocytes. Since monocytes can also be infected by the virus, we investigated peripheral blood monocytes of patients with the acquired immunodeficiency syndrome (AIDS), AIDS-related complex (ARC), and HIV seropositive and seronegative haemophiliacs without symptoms for the expression of the CD4 molecule and for other functionally important surface molecules such as CD11 (C3bi receptor), transferrin receptor, Fc receptor, and the three major histocompatibility complex (MHC) class II antigens HLA-DP, HLA-DR, and HLA-DQ. With immunofluorescence staining and flow cytometry no difference was found between patients and controls for the expression of the CD4 molecule and for the other antigens as assessed by the percentage of positive staining and the specific fluorescence intensity in a double marker analysis. The percentage of CD4+ monocytes was found to be 59.2 +/- 14.4% for 16 patients with AIDS and 52.9 +/- 12.8% for 12 healthy controls. Similar to our results on phenotype, we found no significant difference with respect to the production of tumour necrosis factor (TNF), in that monocytes of AIDS and ARC patients showed an increase in TNF secretion after stimulation with LPS comparable to controls.

AIDS-Related Complex↗
PubMed1987

Immunology of human immunodeficiency virus infection and the acquired immunodeficiency syndrome. An update.

Recent advances in the understanding of the pathogenesis of infection with human immunodeficiency virus (HIV) stems from the demonstration that the membrane glycoprotein, CD4, is the cellular receptor for HIV. This glycoprotein is found mainly on the surface of a major subpopulation of T lymphocytes and also on macrophages, natural killer cells, some B lymphocytes, and neuronal cells. Cells infected with HIV may be destroyed or have their normal function impaired. Host immune responses to HIV are poor and are not sustained. Neutralizing antibody often is not produced, or HIV may escape from normal immunosuppressive mechanisms through the process of rapid antigenic variation. Factors and markers that may be important in the outcome or that may predict progression of HIV infection are genetic (Gc type), environmental (nutritional status or intercurrent sexually transmitted diseases sustained by the host), and immunologic (rate of decline in number and impairment of function of CD4 lymphocytes and of decline in antibody titers to HIV core protein, p24). A recombinant vaccine will probably be developed for testing in future clinical trials.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[Attempts to produce human monoclonal antibodies to melanoma using the cervical lymph nodes].

Due to their specificity, constant properties and virtually unlimited supply monoclonal antibodies have given an important stimulus to almost every field of biomedical research within the last 10 years. The generation of mouse monoclonal antibodies includes immunisation of mice followed by fusion of mice spleen cells with a murine myeloma cell line. With this procedure hybridomas secreting monoclonal antibodies of a predefined specificity can be obtained. For three major reasons we worked on the establishment of human hybridomas secreting specific antibodies: human antibodies are less immunogenic when used for diagnostic or therapeutic purposes, only human monoclonal antibodies allow the analyses of the human B cell repertoire, there is evidence that human monoclonal antibodies recognise epitopes different from those seen by murine monoclonal antibodies. Therefore, we set out to generate human B cell hybridomas by cell fusion using the human lymphoblastoid B cell line Wi-L2-729 HF2 and lymphocytes from melanoma patients. The lymphocytes were isolated from tumour-draining cervical lymph nodes, stimulated with pokeweed mitogens plus the autologous tumour cells in an enriched tissue culture medium and fused in the presence of polyethylene glycol. Supernatants of hybridomas were screened in a single cell immunosorbent assay with either autologous melanoma cells or established melanoma cell lines fixed to the bottom of Terasaki plates or on cytospin preparations of these cells using the immunoperoxidase staining procedure. We could demonstrate that the tumour draining lymph nodes of these melanoma patients contained B lymphocytes capable of producing antibodies reacting with the tumour cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1986

Transferrin receptors on tumor and bone marrow cells: lack of involvement as target structure for natural killer cells.

Two different experimental approaches based on the specificity of monoclonal antibodies (mAbs) have been taken to verify the hypothesis that the transferrin receptor (TfR) on proliferating cells serves as a common target structure for natural killer (NK) cells. Thus, by the lysostrip technique the TfR was removed from the surface of K562 and Molt4 tumor cells by incubation with two different anti-TfR mAbs. The effect of removal of the TfR was controlled by uptake of radiolabeled transferrin, and by binding of non-cross-reacting monoclonal anti-TfR receptor antibodies. Though the modulation of TfR on the membrane of viable cells was nearly complete, the cells remained fully susceptible to NK lysis. The second approach consisted in removal of TfR-bearing cells from bone marrow cell suspensions by an indirect rosetting technique. Using mAbs bound to ox erythrocytes the rosetted TfR-bearing cells could be removed from bone marrow cell suspension by density centrifugation with an efficiency of greater than 99%. It could be shown that both fractions, TfR+ and TfR- cells, could be lysed to the same degree by NK cells. Thus, the evidence obtained speaks against a role of TfR as a recognition structure for NK cells.

Antibodies, Monoclonal↗
PubMed1986

The epithelial cell surface antigen 17-1A, a target for antibody-mediated tumor therapy: its biochemical nature, tissue distribution and recognition by different monoclonal antibodies.

The antigen defined by MAb 17-1A, raised against colorectal cancer cells and currently used in immunotherapy trials, is a 37 kDa protein containing N-linked glycans as demonstrated by inhibition of glycosylation with tunicamycin. The 17-1A antigen (17-1A Ag) is broadly distributed in normal epithelial tissues and is also found in various types of carcinoma. Quantitative differences in expression between normal and malignant tissues were only apparent in gastric carcinomas. After immunizing mice with fresh colon carcinoma tissue, 4 MAbs were obtained that showed the same tissue reaction pattern as MAb 17-1A and recognized the 17-1A Ag as judged from precipitation and immunoblotting experiments. MAbs M72 and M74 reacted with an anti-idiotypic serum directed against the original MAb 17-1A and were able to block 17-1A binding. In contrast, M77 and M79 are directed against a different epitope. This makes them potentially interesting for passive immunotherapy in regimens involving a combination of MAbs.

Antibodies, Monoclonal↗
PubMed1986

Direct monoclonal antibody rosetting. An effective method for weak antigen detection and large scale separation of human mononuclear cells.

A direct monoclonal antibody rosetting technique is described which serves as a simple, reliable, and very sensitive method for the detection of surface antigens on human leukocytes. In this technique the discriminative monoclonal anti-leukocyte antibodies are directly coupled to ox erythrocytes (oxE) by use of CrCl3. The procedure can be applied to the effective separation of mononuclear cell subsets. By choosing a gradient of appropriate density labeled cells are either isolated in high purity or quantitatively eliminated. This technique proved to be particularly suitable for the large scale purification of autologous or allogeneic bone marrow transplants where either leukemic cells or T cells have to be completely eliminated without damaging sensitive stem cells.

Animals↗
PubMed1986

Cytolytic T cell clones derived from liver tissue of patients with chronic hepatitis B.

To study the role of cell-mediated immunity in chronic hepatitis B (cHB) we have cloned T cells from liver biopsies of 14 patients with cHB. As a first step, T cell lines were established from lymphocytes infiltrating the liver by culturing the biopsied specimens with autologous feeder cells and interleukin 2 (IL2). Fifty-eight clones obtained by limiting dilution showed phenotypic stability over periods of 2-26 weeks. Of the 58 clones 50 were of the "cytotoxic/suppressor" T cell subset (CD8) as defined by the monoclonal antibody T811. Only 8 of 58 clones were of the "helper/inducer" phenotype (CD4) as defined by the monoclonal antibody T151. Functional studies on 9 clones (7 of CD8+ phenotype, 2 of CD4+ phenotype) revealed high cytotoxic activity of all of these clones in a lectin-dependent cell-mediated cytotoxicity assay reflecting the killing capacity of cytotoxic T lymphocytes. All 9 clones lacked significant natural killer activity, while two additional CD8+ clones that also expressed the VEP13 antigen showed significant natural killer activity. For none of the clones tested could killer cell activity (ADCC) be demonstrated. The studies demonstrate that the clonal expansion of T lymphocytes from liver biopsies of patients with cHB in the absence of detectable antigen is possible. The propagation of in vivo activated cytolytic T lymphocytes points to an active role of these cells in the pathogenesis of this disease.

Adult↗
PubMed1986

Detection of both isotypes of complement C4, C4A and C4B, in normal human glomeruli.

Monoclonal antibodies reactive against the complement C4A and C4B isotypic components were used in an immunoperoxidase technique for the histological study of normal human renal tissue. Prominent staining with both antibodies was seen in the mesangial areas of all normal kidney sections investigated. Occasional staining of arteriolar walls of the same tissues, however, was also observed. In contrast, no mesangial staining was seen using monoclonal antibodies reactive against other 'early' complement components, such as C1q and C3. Specificity of the glomerular staining with the anti-C4 reagents was demonstrated in two patients possessing only the C4A serum component but lacking genetically the C4B locus products. As would be predicted, glomerular staining with the anti-C4A reagent, but not anti-C4B, was clearly demonstrable. It is concluded that both isotypes of complement C4 are present in normal human glomeruli and thus might be operative for normal mesangial function.

Antibodies, Monoclonal↗
PubMed1986

Complete sequence of HLA-B27 cDNA identified through the characterization of structural markers unique to the HLA-A, -B, and -C allelic series.

Antigen HLA-B27 is a high-risk genetic factor with respect to a group of rheumatoid disorders, especially ankylosing spondylitis. A cDNA library was constructed from an autozygous B-cell line expressing HLA-B27, HLA-Cw1, and the previously cloned HLA-A2 antigen. Clones detected with an HLA probe were isolated and sorted into homology groups by differential hybridization and restriction maps. Nucleotide sequencing allowed the unambiguous assignment of cDNAs to HLA-A, -B, and -C loci. The HLA-B27 mRNA has the structural features and the codon variability typical of an HLA class I transcript but it specifies two uncommon amino acid replacements: a cysteine in position 67 and a serine in position 131. The latter substitution may have functional consequences, because it occurs in a conserved region and at a position invariably occupied by a species-specific arginine in humans and lysine in mice. The availability of the complete sequence of HLA-B27 and of the partial sequence of HLA-Cw1 allows the recognition of locus-specific sequence markers, particularly, but not exclusively, in the transmembrane and cytoplasmic domains.

Base Sequence↗
PubMed1986

Protection of mice against tetanus toxin by combination of two human monoclonal antibodies recognizing distinct epitopes on the toxin molecule.

Human B-lymphocytes were fused with the human lymphoblastoid B-cell line WI-L2-729 HF2. Hybridoma frequencies were in the range of 10(-5) when the mononuclear cells were (a) prestimulated with pokeweed mitogen (PWM), (b) fused with polyethyleneglycol (PEG), and (c) selected in a hypoxanthine-azaserine (HAza) containing medium. To generate monoclonal antibodies (MAb) specific for tetanus toxin (TToxin) human spleen cells were precultured with PWM plus tetanus toxoid (TToxoid) in two separate fusions. Two hybridomas were selected based on high binding activity using an enzyme-linked immunosorbent assay (ELISA) for TToxoid. Both hybridomas, cloned twice and designated anti-TT1 and anti-TT2, exhibited a near tetraploid karyotype and showed stable production of antibody (0.15 micrograms/ml) over several months. Using ELISA for fragments of TToxin and the immunoblotting technique, the two IgG1 monoclonal antibodies were found to bind to the heavy chain portion of the B-fragment (anti-TT1) and on the C-fragment (anti-TT2) of the toxin. When tested in an ELISA with TToxin the combination of anti-TT1 and anti-TT2 showed higher binding activity than either reagent alone. In an in vivo neutralization assay mice were completely protected against TToxin by the combination of the two antibodies while either antibody alone resulted only in a delay of death of the mice. These findings demonstrate that a cocktail of appropriate human monoclonal antibodies can be far superior to a single reagent when used in a therapeutic setting.

Animals↗
PubMed1986

Biochemical and epitope analysis of the 17-1A membrane antigen.

The antigen recognized by the monoclonal anti-colon carcinoma antibody 17-1A was found to be a 37 kD glycoprotein in three human colon carcinoma cell lines. The 17-1A antigen (17-1A Ag) contains asparagine-linked carbohydrates as determined by inhibition of glycosylation with tunicamycin. After reduction of 17-1A precipitates with 2-mercaptoethanol two bands of 33 and 40 kD were obtained from the cell lines DLD-1 and HT-29, but only one band from cell line WiDr. Four new MAbs generated against fresh colon carcinoma tissue were shown to be directed against the 17-1A Ag by immunoprecipitation and Western blotting. Two of these MAbs appear to define a novel epitope on the 17-1A Ag as judged from cross-blocking experiments and idiotype expression. Immunohistochemical analysis revealed that the 17-1A Ag is distinctly expressed on a variety of normal and malignant epithelial tissues.

Antigen-Antibody Complex↗