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Biomedical subjects

G Garotta

Publications and source records attributed to G Garotta.

At least 91 records · Page 5Linked to original sources
PubMed1987

In vitro studies in nickel allergy: diagnostic value of a dual parameter analysis.

A comparison was made between the diagnostic value of assaying nickel-induced lymphocyte proliferation (lymphocyte transformation test, LTT) and migration inhibition factor (MIF) production in nickel contact sensitivity. Although lymphocyte proliferation was significantly increased in the group of patients with skin test reactivity to nickel, positive LTT were also frequently found in skin test-negative subjects: in 63% of subjects with and in 30% of subjects without a history of metal allergy. This would limit the value of the LTT as an in vitro correlate of skin test reactivity. However, in certain patients positive lymphocyte transformation may reveal nickel sensitization at a time of undetectable skin reactivity. Data obtained with the macrophage migration inhibition test (MMIT) showed a good correlation with nickel patch test reactions. Accurate determination of MIF became feasible by using cells from the human monocytoid cell line U937 as target cells in a microdroplet agarose assay. Using this MMIT, positive reactions occurred in 13% of the healthy controls and false-negative reactions were found in 26% of patients with positive skin test reactivity to nickel. As LTT and MMIT data appeared to be only weakly correlated in the individuals tested, a dual parameter analysis was performed. An excellent correlation [p = 1.8 (10(-8]] was found between skin test and in vitro reactivity for individuals with matching in vitro results (60% of all individuals tested). In those individuals with discordant in vitro data, skin testing will remain indispensable for diagnosing nickel allergy.

Cell Line↗
PubMed1986

Functional antagonism between type I and type II interferons on human macrophages.

A three-day treatment with IFN-gamma enhanced up to 300% the capacity of human monocytes and macrophages to produce H2O2 during the respiratory burst. IFN-alpha or -beta (type I IFNs), which did not by themselves influence the burst, were found to antagonize the enhancing effect of IFN-gamma (type II IFN). The antagonism was concentration-dependent and required the presence of type I IFNs during the whole period of IFN-gamma pretreatment. These results suggest that the host defense function of mononuclear phagocytes may be controlled by the relative local concentrations of type I and type II IFNs.

Humans↗
PubMed1986

Identity between human interferon-gamma and "macrophage-activating factor" produced by human T lymphocytes.

Human peripheral blood monocytes purified by counterflow elutriation were activated in vitro by human natural or recombinant interferon-gamma (IFN-gamma) as shown by enhanced killing of Listeria monocytogenes and increased production of H2O2 in response to phorbol myristate acetate. Half-maximal stimulation for macrophage activation (MAF) was observed with 10-20 antiviral U/ml of purified recombinant IFN-gamma. These MAF activities were found to correlate with the antiviral activity dependent on IFN-gamma under several experimental conditions. Both activities were recovered together from supernatants of concanavalin A-stimulated peripheral blood mononuclear cells and in the media of a large number of T cell clones of different specificities. The parallelism between the two activities was also observed upon fractionation of culture media from producing cells and upon treatment of such preparations with low pH and high temperature. Finally, three antibodies with different specificities were found to abrogate the MAF and antiviral activities from lymphocyte culture supernatant. These results indicate that MAF released by stimulated lymphocytes is identical to IFN-gamma.

Antiviral Agents↗
PubMed1985

A sensitive and quantitative microassay for the detection of mycoplasma contamination: inhibition of IL-2 dependent cell line proliferation.

A simple, rapid and sensitive microassay for mycoplasma detection in cell culture is reported. The assay is based on the fact that culture supernatants from contaminated cells inhibit [3H]thymidine incorporation by an IL-2 dependent mouse cytotoxic T cell line (CTLL). The mechanism of inhibition is related to the production by several mycoplasma strains of a pyrimidine-specific nucleoside phosphorylase which can degrade the radiolabelled thymidine used for the measurement of DNA synthesis. These strains were the commonest contaminants in cultures of 24 cell lines from 5 different sources. To establish the sensitivity of the test to detect mycoplasmas we have also used the inhibition assay to monitor the clearance of mycoplasma from 2 contaminated cell lines.

Cell Division↗
PubMed1985

Isolation and characterization of Ni-specific T cell clones from patients with Ni-contact dermatitis.

Ni-specific T lymphocyte clones (TLC) were isolated from two patients with Ni-contact dermatitis. All of the isolated TLC required both histocompatible antigen-presenting cells (APC) and Ni for induction of proliferation. By using a panel of HLA-typed Epstein Barr virus-transformed B cells (EBV-B cells) as APC and monoclonal anti-DR antibody, the clones were shown to recognize Ni in the context of HLA class II determinants. All of the clones that were isolated are OKT3+, OKT4+, OKT8-. In the presence of Ni, they polyclonally activate autologous B cells, and in the presence of Ni and autologous EBV-B cells, they produce IL 2 and very high levels of IFN-gamma. The Ni-specific clones should be helpful in the identification of the Ni-induced antigen which is recognized by T cells.

Antigen-Presenting Cells↗
PubMed1981

Modulation of expression of HLA components at the cell surface induced by anti-beta 2m reagents.

Antibodies against lymphocytes surface components are able to rearrange profoundly the topography of the cell membrane with a differential modulation of surface antigens. Of particular interest is the effect of anti-beta 2m reagents, which are able to suppress completely the reactivity of epitopes carried by the two chains of the ABC dimers, while th expressivity of other antigens, such as DR, is significantly increased. These results have been obtained with immunoradiobinding under a variety of conditions, thus confirming the validity of the "bb" (beta 2m blanketing) test.

Animals↗
PubMed1980

Quantitative analysis of cell surface HLA structures by means of monoclonal antibodies.

Quantitative data on the binding of murine monoclonal antibodies ot whole human lymphoblastoid lines and peripheral blood lymphocytes (PBL) are reported. Antibodies reacting with beta 2m or a common part of the HLA heavy chains and nonpolymorphic determinants of the DR dimer were used. The equilibrium constant (K) of the reaction and the total number of antigenic determinants was graphically estimated. For the above-mentioned antibodies, K ranged between 5 X 10(8) and 4 C 10(9) l/mole at 0 degrees C and progressively decreased with the increasing temperature. T cells expressed less HLA and beta 2M determinants than the B cells. The number of determinants per surface unit is higher on the B cell from PBL than on E.B. virus-transformed cell lines and is generally very low, suggesting that the complement-dependent cytotoxic activity is a phenomenon depending on membrane fluidity. A portion of beta 2m seems not to be bound to the HLA heavy chains on B cells as well as on T line surface, as already shown for Molt 4 line.

Antibodies↗
PubMed1979

Separation of human cells bearing HLA-DR antigens using a monoclonal antibody rosetting method.

A technique is described for enriching, from human blood, cells bearing HLA-DR antigens. The method depends on the use of monoclonal mouse antibody which reacts with HLA-DR structures. Cells to which this antibody has bound can be separated after rosetting with bovine erythrocytes coated with anti-mouse immunoglobulin. The cells thus enriched may be used for HLA-DR typing by standard cytotoxicity methods with allogeneic sera.

Antibodies, Anti-Idiotypic↗
PubMed1978

Different colony stimulating activity by tumoral ascitic fluid and conditioned media.

The effects of intraperitoneal Ehrlich ascites tumor (ET) growth on the kinetics of hemopoietic stem cells in the host bone marrow were studied using the spleen colony and the soft agar culture techniques. There is a decrease in spleen colony forming capacity of bone marrow of ET bearing mice, whereas in vitro assays of the committed macrophage granulocyte precursors, by the soft agar method, show that in the same circumstances a high yield of granulopoietic colonies can still be obtained. A shift of the CFU-c/CFU-s ratio from 15 to 36 thus occurs. Moreover, ascitic fluid from tumoral mice displays strong activity as CSF on normal mouse marrow, twice as strong as the standard mouse embryo CSF. When conditioned medium from cultures of ET cells (ET-CM) is tested, the pattern of agar colonies obtained is different from the previously obtained pattern of growth kinetics; furthermore many colonies are composed of undifferentiated cells. The hypothesis is suggested that among the variety of known CSF's, the ET-CM represents a unique factor, capable of inducing proliferation of marrow CFU-c, but only limited differentiation.

Animals↗
PubMed1976

T-cell precursors in mice bearing the Ehrlich ascites tumors.

Mice bearing Ehrlich ascites tumors and challenged with sheep erythrocytes produced fewer plaque-forming cells than did normal mice. At the same time the immunosuppression developed, the number of T lymphocytes in the thymus and spleen were reduced significantly. In the spleen, the number of B lymphocytes remained constant during carcinogenesis, whereas that of the macrophages increased significantly, as compared to the controls. In this paper, we demonstrated that the mechanism responsible for thymus and spleen depletion of theta antigen-bearing cells had to be ascribed to fewer T-lymphocyte precursors in the bone marrow of mice with cancer. The reduction of T-lymphocyte precursors was probably caused by the same "soluble factor(s)" produced by Ehrlich ascites tumor cells, which also interfered with the proliferation of myelopoietic stem cells in the bone marrow of mice with this neoplasm, as we previously reported. By performing several reconstitution experiments of lethally X-irradiated hosts, we determined that the immunodepression by Ehrlich ascites tumor cells was readily reversible, and the alteration of the T:B lymphocyte ratio in the spleen had a minor function, if any, in the pathogenesis of the immunosuppression.

Animals↗
PubMedDate not supplied

Differential cytokine production in stimulated blood cultures from intensive care patients with bacterial infections.

Mice infected with bacteria develop an interferon-gamma (IFN-gamma) dependent hypersensitivity to lipopolysaccharide (LPS) and other bacterial components. The broader aim of this study is to find out whether such hypersensitivity also occurs in patients suffering from bacterial infections. The capacity of stimulated peripheral blood cells from infected, intensive-care patients to produce cytokines (IFN-gamma, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6)) was compared to that of healthy donors. Culturing of the cells was carried out preferentially in whole blood diluted 1:3. Whole blood cultures (WBC) were stimulated with lipopolysaccharide (LPS), whole killed Salmonella typhimurium and Staphylococcus aureus and concanavalin A (ConA), and the cytokine production was determined. Two main findings emerged from this study: The IFN-gamma production by WBC of patients was, compared to healthy donors, markedly suppressed, regardless of stimulus used. Further, patients' WBC exhibited a suppressed TNF-alpha production after stimulation with LPS. Surprisingly, following stimulation with bacteria (S. typhimurium and S. aureus) an elevated TNF-alpha and IL-6 response was obtained. Thus, in severely infected patients the cytokine responses of peripheral blood cells to LPS may be suppressed, while the response to other bacterial components is enhanced.

Adolescent↗