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Biomedical subjects

G Riethmüller

Publications and source records attributed to G Riethmüller.

At least 235 records · Page 13Linked to original sources
PubMed1981

Surface antigens of human melanoma cells defined by monoclonal antibodies. I. Biochemical characterization of two antigens found on cell lines and fresh tumors of diverse tissue origin.

Monoclonal antibodies were produced against melanoma cell lines derived from patients presently disease free. Based on tissue distribution of binding, the antibodies obtained could be used to classify melanoma surface antigens into groupings similar to those obtained from studies of autologous and xenogeneic antibodies. Three antibodies (21.43, 15.75 and 15.95) reacted with the immunizing tumor but not with peripheral blood lymphocytes or a lymphoblastoid cell line derived from the tumor donor. When tested on a broader cell panel, antibody 21.43 reacted only with melanoma lines, while antibodies 15.75 and 15.95 reacted with carcinoma cell lines as well as with the majority of melanoma cell lines. Antibody 15.95 precipitated a 49000 dalton glycoprotein from both melanoma and carcinoma cells. Antibody 15.75 precipitated a 74000 dalton glycoprotein from the surface of melanoma and carcinoma cell lines which is also found on freshly isolated tumor cells from melanoma and carcinoma metastases in vivo.

Animals↗
PubMed1981

A subset of human cells isolated and characterized by monoclonal antibodies.

Monoclonal antibodies were induced against leukemic T cells from a patient with chronic lymphocytic leukemia exhibiting natural killer (NK) activity. Two antibodies, termed T811 and M522, reacted by indirect immunofluorescence with distinct sub-populations of normal human mononuclear blood cells. The antibody T811 defines a surface antigen which is restricted to a subset of the T cell lineage. The antigen recognized by the second antibody, M522, is expressed on monocytes and polymorphonuclear leukocytes and, in addition, on 9-17% of nonadherent peripheral blood leukocytes (NAL). It is shown that the total NK activity of NAL is confined to the subset of cells expressing the M522-defined antigen. Moreover, the portion of NK cytotoxicity associated with T lymphocytes is mediated by a subpopulation which is characterized by the simultaneous expression of the T811- and the M522-defined antigens. This population comprises about 4% of NAL and could be isolated to a purity of greater than 85%.

Animals↗
PubMed1981

Natural killer cell activity during treatment with fibroblast interferon.

Short- and long-term effects on natural cytotoxicity (NC) of i.v. administration of human fibroblast interferon (IFN--beta) was studied in patients with HBsAg positive chronic active hepatitis. Short-term kinetics demonstrated after a transient fall of NC a severalfold increase of NK activity after 24 hours. Long-term kinetics of NC revealed following features: The highest relative increase was seen during the initial phase of IFN--beta application. In all patients monitored so far the enhanced NK activity could be maintained during 2 to 4 weeks of therapy. Over a period of several weeks a gradual decrease of augmented NK activity was observed in spite of continued application of high doses of IFN--beta. These findings indicate that in-vivo administration of IFN--beta results in an augmentation of natural cytotoxicity in man. Prolonged treatment with IFN--beta seems to "exhaust" the NK cell system.

Adult↗
PubMed1981

Human T cell differentiation antigens characterizing a cytotoxic/suppressor T cell subset.

Monoclonal antibodies were raised against the leukemic T cells from a patient with chronic lymphocytic leukemia. Two antibodies, termed T411 and T811, were obtained which were reactive by indirect immunofluorescence only with cells of the T cell lineage. The T411 antibody recognized a polypeptide chain of 100,000 dalton apparent molecular weight which was present on the surface of 94 +/- 4% of peripheral blood T lymphocytes, but only on 20 +/- 8% of thymus cells. The antibody T811 reacted with a surface molecule composed of 2 poly-peptide chains of 32,000 and 34,000 dalton apparent molecular weight, which was expressed only on 25 +/- 10% of blood T lymphocytes and on 90 +/- 4% of thymus cells. Functional analysis of the T811+ and T811- T cell subsets isolated by rosetting with anti-mouse Ig coated ox erythrocytes revealed that both subpopulations were able to mount a proliferative response to allo-antigens, whereas allo-antigen induced cytotoxic cells and their precursors were only found in the T811+ subset. The pokeweed mitogen induced in vitro differentiation of B lymphocytes into immunoglobulin secreting cells was dependent on the presence of the T811- subset, whereas the T811+ T cells efficiently suppressed this differentiation.

Animals↗
PubMed1981

Natural and antibody-dependent cellular cytotoxicity in tumour-adherent T lymphocytes: expression of Fc receptors and of a human T-subgroup-specific antigen.

Adherence of human lymphocytes to allogeneic tumour cell monolayers was found to depend on the presence of monocytes. Adherent lymphocytes could be separated from tumour cells by treatment with lidocaine followed by nylon wool passage. Tumour-adherent cells (70% E-RFC, 45% Fc gamma-R, 23% Fc mu-R, 5% monocytes) exhibited enriched natural killer (NK) activity not only against the tumour cell line used for isolation but also against seven other targets. When T cells were isolated subsequently as E-rosettes by density gradient centrifugation through Percoll, the enrichment in cytotoxicity was even more pronounced. Tumour-adherent T cells were severalfold enriched in both NK and antibody-dependent cell-mediated cytotoxicity (ADCC) activity. However, this enrichment was not paralleled by a concomitant increase in the number of T gamma cells (tumour-adherent T cells: 17% T gamma, 40% T mu ; tumour-nonadherent T cells: 12% T gamma, 60% T mu). Marked differences could be observed by staining with a monoclonal antibody that was raised against human leukaemic T gamma cells of high NK and ADCC activity. This antibody (T 8-11) stained 60% of tumour-adherent T cells, 20% of nonadherent T cells and 29% of T-cell controls. These results indicate that the spontaneous cytotoxic activity of human T cells resides within a small population, most of which are characterized by a specific surface antigen but not by conventional Fc gamma receptors.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1980

Efficient separation of human T lymphocytes from venous blood using PVP-coated colloidal silica particles (percoll).

In a comparative study, human peripheral T lymphocytes were separated as E rosettes by density centrifugation through various gradient media. Sheep red blood cells (SRBC) were removed by dissociation of the E rosettes at 37 degrees C with subsequent centrifugation on a similar density gradient prewarmed to 37 degrees C. In particular, gradients made of Ficoll Urovison were compared with Percoll gradients with regard to both separation steps. Using Percoll gradients, a maximal T cell recovery of 75% was obtained, whereas Ficoll separation yielded only 46%. T lymphocytes separated with Percoll exhibited equal viability compared to Ficoll isolated cells and consisted of 98% EAET-RFC. No inhibition of cellular function by Percoll treatment was detected, whereas Ficoll treatment led to an impaired mitogenic response. An inherent mitogenicity of Percoll was not observed. The method described results in considerably shortened centrifugation times due to the low viscosity of the Percoll medium and simultaneously seems to be less harmful to the rather fragile rosettes. Reproducibility was found to depend on careful control of density and osmolarity of the Percoll medium.

Cell Separation↗
PubMed1979

Hairy cell leukaemia: surface markers and functional capacities of the leukaemic cells analysed in eight patients.

In eight patients with hairy cell leukaemia (HCL) peripheral blood cells and in two patients also spleen cells were analysed for surface markers and functional capacities. Only cells containing the tartrate resistant isoenzyme 5 of the acid phosphatase were considered. Hairy cells (HC) of all patients were found to adhere spontaneously to glass and plastic surfaces and to spread after adherence like monocytes. They ingested latex particles of more than 1 micron diameter, but, in contrast to monocytes, did not phagocytose erythrocytes sensitized either by IgM or by IgG antibodies. HC of all patients bore Fc-receptors with a high binding affinity for aggregated IgG. Using 125 I-labelled F(ab')2-fragments of monospecific antibodies in autoradiography, only one light chain type was detected on HC of individual patients. In four patients mu- and delta-chains were simultaneously expressed on HC, whereas in two patients only gamma-chains and in one case only mu-chains were observed on HC. One patient showed a combination of gamma- and delta-chains on his HC. A great variation in density of surface immunoglobulings of HC was observed within individual patients. After removal by capping, surface immunoglobulin reappeared on HC during cell culture, but more slowly than on normal B-lymphocytes. As shown in two patients by internal labelling, HC secreted immunoglobulin light chains, but no heavy chains. On the basis of these findings the classification of HC as belonging to the B-cell lineage, rather than to the monocytic lineage, seems to be justified.

Adult↗
PubMed1977

Procoagulant activity of activated monocytes.

Endotoxin-stimulated monocytes develop a very high tissue-factor-like activity as compared to an equivalent number of monocytes in a preparation of monocyte-enriched mononuclear blood cells obtained by Ficoll-Urovision density gradient centrifugation which is not exposed to endotoxin. In monocytes which were obtained by plastic adherence from the monocyte-enriched mononuclear blood cells, the tissue factor activity was as high as in the endotoxin-stimulated monocytes.

Bacterial Toxins↗
PubMed1976

[Hairy cell leukemia. Characterization of the leukemic cell: surface immunoglobulins, Fc-receptors and stimulation by mitogens (author's transl)].

In four patients with hairy cell leukemia the expression of surface immunoglobulins and Fc-receptors on the leukemic cells as well as the stimulation of the leukemic cells by various T- and B-cell mitogens was studied. Using a combined cytochemical radioautographic method the tartrate resistant isoenzyme of the acid phosphatase and immunological markers could be demonstrated simultaneously on single cells. Surface immunoglobulins were detected by 125I-labelled (Fab')2-fragments of monospecific anti-heavy-chain-antibodies. In two patients only mu- and delta-determinants were found on the isoenzyme-positive hairy cells; in one patient 86% and in the other 44% of these cells carried both heavy chains on the same cell. Another patient showed both gamma- and delta-chains on the isoenzyme-positive cells and the fourth patient gamma-chains only. When the hairy cells of one patient were cultured in vitro in human serum-free medium for 14 days, mu- and delta-determinants were found just as on freshly isolated cells suggesting that hairy cells synthesize immunoglobulins. By indirect immunofluorescence the surface-Ig on hairy cells was shown to be capped very rapidly at room temperature. The concentrated surface-Ig was found over that cytoplasmic area where most of the ingested latex particles were located. In addition, using 125I-labelled aggregated human IgG (M.W. 5-15 X 10(6)), Fc-receptors were found on virtually all of the isoenzyme-containing hairy cells in all four patients. Furthermore, a distinct, low-degree stimulation of the isoenzyme-positive hairy cells could be demonstrated when the cells were cultured in the presence of pokeweed mitogen or Lima-bean lectin (B- and T-cell-mitogens), whereas no stimulation was observed by phytohemagglutinin and concanavalin A (T-cell-mitogens). In three patients studied, isoenzyme-positive hairy cells were negative with regard to rosette formation with sheep erythrocytes.

Acid Phosphatase↗
PubMed1976

[Hairy cell leukaemia. I. Clinical features, cytochemistry, phagocytosis, establishment of permanent growing cell lines (author's transl)].

In seven patients the diagnosis of hair cell leukaemia (leukaemic reticuloendotheliosis) was confirmed cytochemically and histologically. Splenectomy, in six patients, apparently favourably influenced the course. Isoenzyme 5 of the acid phosphatase was demonstrated in the hairy cells of all patients. Reaction of alpha-naphthylacetate esterase was moderately positive in the hairy cells. Phagocytosis of latex and India-ink particles was demonstrated especially in tartrate-resistant cells of one patient. In two patients eight permanently growing cell lines were demonstrated from leucocytes and defined cytochemically. Capacity for phagocytosis of hairy cells and positive reaction of alpha-naphthylacetate esterase in the hairy cells suggest properties of monocytes. But it is not possible definitively to classify the hairy cells among B-cells or monocytes.

Acid Phosphatase↗
PubMed1976

[Fc receptors and surface immunoglobulins in cells of hairy cell leukemia].

Using 125I-labelled aggregated IgG in a quantitative assay a strong expression of Fc-receptors was found on the leukemic cells of a patient with hairy cell leukemia. The Fc-receptor activity on these cells was much higher than that on monocytes and B-lymphocytes from normal blood. Surface immunoglobulins were detected by radioautography using radioactively labelled (Fab')2-fragments of monospecific antibodies directed against immunoglobulin heavy chains. Prior to radioautography the cells were stained for the tartrate resistant acid phosphatase. It was found that all cells containing this enzyme bore sigma-chains on their surface. On more than 90% of these cells a simultaneous expression of mu-chains was detected. gamma-Chains could only be demonstrated on cells which were negative for the tartrate resistant acid phosphatase; part of these cells, however, were hairy cells by morphological criteria.

Acid Phosphatase↗
PubMed1976

Cell-mediated cytotoxicity for melanoma tumor cells: detection by a (3H) proline release assay.

An in vitro lymphocyte-mediated cytotoxicity assay using [3H]proline-labeled target cells is described. The assay, modified from an original procedure of Bean et al., assesses the release of [3-H]proline by filtering the total culture fluid containing both trypsinized tumor cells and effector cells. Filtration is performed with a semiautomatic harvesting device using low suction pressure and large-diameter glass filters. Pretreatment of filters with whole serum diminishes adsorption of cell-free radioactive material considerably and thus increases the sensitivity of the assay. Nearly 100% of the radioactivity could be recovered with this harvesting device. The technique allowed the detection of cytolytic activities of lymphocytes after 6 h of incubation. Lymphocytes from patients with primary malignant melanoma showed a significantly higher cytolytic reactivity (P less than 0.001) than normal donors' lymphocytes against three different melanoma cell lines. In a series of parallel experiments on 36 patients and 18 normal donors, this modification of the [3H]proline test was compared with three different assays: the conventional microcytotoxicity test of Takasugi and Klein, the original [3H]proline microcytotoxicity test of Bean et al., and the viability count of tumor cells.

Cell Line↗