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Biomedical subjects

D Zagury

Publications and source records attributed to D Zagury.

At least 91 records · Page 5Linked to original sources
PubMed1983

Human normal CTL clones: generation and properties.

This study reports the production of clones of human killer T cells grown in the presence of TCGF4 following sensitization in MLC against (1) allogeneic cells, (2) autologous Bebv+ lymphocytes, or (3) autologous lymphoma cells. Sensitization against the tumor cells required the addition of macrophages. The expression of the cytotoxic activity of the cloned T lymphocytes required re-stimulation with the specific stimulator cells. The cytotoxic activity seemed to be MHC-restricted, since (1) cloned allosensitized CTL lysed their corresponding allogeneic targets, but did not lyse autologous Bebv+ cell or K562 cells; (2) cloned CTL sensitized against autologous Bebv+ cells lysed their autologous targets but not allogeneic Bebv+ targets or K562 cells; and (3) cloned CTL sensitized against autologous Burkitt lymphoma cells lysed their corresponding lymphoma targets or autologous Bebv+ targets but did not lyse allogeneic lymphoma cells or Bebv+ cells from the same allogeneic lymphoma cells or Bebv+ cells from the same allogeneic donors. The cloned CTL were homogeneous in expressing the OK T8 molecules and in being negative for T4, T10 or M1. At any given time, 25-45% of the cloned cells manifested lytic activity. The ultrastructural properties and cell surface OK T markers were different from those of cloned human NK cells. Emphasis is focused on the differences between the structural, functional and culture characteristics of CTL clones produced by direct isolation of MLC responder cells forming conjugates with specific target cells and those of clones from transformed T-cell lines or from T hybridomas.

Antigens, Surface↗
PubMed1983

Diminished interleukin-2 activity production in cancer patients bearing solid tumors and its relationship with natural killer cells.

Interleukin-2 (IL-2) activity production by stimulated peripheral blood lymphocytes (PBL) from solid tumor bearing cancer patients was lower than in normal subjects. Natural-killer (NK) cell activity in the PBL of cancer patients was very significantly correlated to IL-2 activity production (P less than 0.001). These results might suggest a central role for IL-2 in the immune dysfunctions in cancer patients, and the possible use of IL-2 as an immunological response modifier in these patients.

Adult↗
PubMed1983

Interferon effect on cytolytic T lymphocytes in a single cycle assay.

In this study we analyse cell-mediated cytotoxicity by the use of 51chromium release and the killer cell enumeration assay. The latter enabled us to estimate cell-mediated cytotoxicity in a single cycle, which confirms the protective effect of interferon (IFN) after target cell treatment. This anti-cytolytic resistance is detected best by microassociation when effector and target cells are separately treated with IFN and associated thereafter. We suggest that, in inflammatory areas, enhanced cytotoxic activity of the IFN-treated effector cells is only operative before the establishment of protection in the targets, which is somewhat slower and appears in about 18 hr. Resistance of the targets could be at least partly attributed to the incapacity of effector cells to bind to them.

Animals↗
PubMed1982

[Polyenzymatic activation of cellular hydrolases induced by interferon; its role in cytolysis and other cellular manifestations induced by interferon].

Interferon (IFN) treatment of human effector T cells activates CMC directed against K562 targets. An increase of the activity of the different hydrolytic enzymes tested (hexosaminidase and acid-phosphatase) measured in the effector cell population parallels cytolysis activation. IFN and IFN inducers (PIC) treatment of cultured murine L-929 cells generate molecular mediated cytolysis. An increase of hydrolytic enzyme activity (hexosaminidase; B-glucuronidase, acid and alkalin phosphatases) precedes cell lysis. Thus, in both cytolytic systems, IFN induced a polyenzymatic activation of hydrolases. This activation is similar to coordinate enzyme induction discovered by Hosli [16] in pathological and experimental instances, when absorbed substrates cannot be hydrolyzed by lack of specific enzymes. Activation of hydrolytic enzymes induced by IFN which determines its enhancing effect on CMC and on fibroblast autolysis [17] could speculatively explain other effects of IFN such as antiviral action, diminution of cell protein synthesis, inhibition of cell division or molecular alterations of cell surface.

Alkaline Phosphatase↗
PubMed1982

Direct analysis of individual killer T cells: susceptibility of target cells to lysis and secretion of hydrolytic enzymes by CTL.

Direct identification, enumeration and biological characterization of cytolytic T lymphocytes (CTL) complementing the chromium release test had allowed us to propose a mechanism for T-cell mediated cytotoxicity (T-CMC). One CTL without accessory cells is able to lyse a specific target. Binding which allows cell contact (E-T doublets), should activate effector CTLs and render target cells susceptible to lysis. Secretion of hydrolytic enzymes localized at the CTL-target junction accounts for the lethal hit given by CTLs to susceptible targets. This hypothesis that the resulting cell lesion is identified with an alteration of the lipid bilayer membrane had been confirmed by single killer cell study. Furthermore, we have proposed that phospholipase enzymes are involved in the membrane alterations, since susceptible targets bound to effector cells (conjugates) were lysed in a much higher yield in the presence of phospholipase. Membrane cell lesion determined by hydrolytic enzyme (phospholipase) could represent a basic general mechanism for other cellular or molecular mediated processes.

Animals↗
PubMed1982

A general method for the cytochemical and ultrastructural studies of human lymphocyte subsets defined by monoclonal antibodies.

After incubation with monoclonal mouse antisera raised against membrane differentiation antigens, subsets of human lymphocytes can be detected by means of latex microspheres or ox erythrocytes coated with anti-mouse Ig antibodies. Optimal conditions are described using a panel of monoclonal antisera (Ortho Pharmaceuticals and New England Nuclear). The method is as sensitive as the complement-mediated microcytotoxicity assay, is rapid, easy to perform and permits exhaustive light and electron microscopic studies of lymphocytes bound to the carrier particles. The advantages of the simultaneous analysis of cytological features and monoclonal antibody-defined surface markers in normal and pathological individual lymphocytes are discussed with regard to lymphoid cell maturation and neoplastic lymphocyte classification.

Animals↗
PubMed1981

Production of human T-lymphocyte clones. I. monoclonal culture and functional cytotoxic maturation.

Well-defined clones of human T-lymphocytes were produced and monoclonal T-cell cultures were maintained for long periods of time. Single T-lymphocytes were isolated with the help of a micropipette from PBL cultures prior to any cellular stimulation (MLC), collected separately at the bottom of a 200 microliter tissue culture microwell under the control of stereomicroscopic observation, and cultured with irradiated lymphoid cells in the presence of TCGF. After 12 days, 20-50% of the seeded wells exhibited clones of 3 x 104-105 T-lymphocytes, which were transferred to larger tissue culture wells (2 ml, LINBRO) for long-term culture. Recloning of the growing cloned cells under the same conditions as the primary culture was carried out successfully. In the preliminary cytotoxic assays performed in 11 clones (a) a marked activity directed against lectin-coated targets was observed in may clones; (b) an important NK-like activity was exhibited by the clone 45B9 (65% of the tested cells lysed K562 cell targets); (c) 2 clones did not demonstrate cytotoxic activity against either PHA-coated L-1210 cells or K562 cell targets. These results could be explained hypothetically by the difference of functional maturation of T-cells within each clone.

Cell Differentiation↗
PubMed1981

Polyenzymatic activation of cellular hydrolases induced by interferon; its role in cell lysis and other interferon--related phenomena.

Treatment of human cultured T cells by interferon (IFN), which enhances cell-mediated cytotoxicity directed against human K562 cell targets (NK-like activity) induces an activation of cell hydrolases. Treatment of mouse cultured L929 cells by IFN and double strand RNA enhancing cell autolysis induces first an activation of tested hydrolases (hexosaminidase, beta-glucuronidase, acid and alkaline phosphatases). Polyenzymatic activation of hydrolases induced by IFN is similar to coordinate enzymatic induction described by Hosli which occurs by lack of specific enzyme when non-digestible substrates are absorbed by cells. It is hypothesized that the polyenzymatic activation which accounts for cell lysis is a general defense mechanism which might also explain other actions related to IFN such as antiviral effect, inhibition of cell division, diminution of protein synthesis and cell surface alteration.

Animals↗
PubMed1980

[Long-term production and culture of clones of human T-lymphocytes].

Culture of blood T lymphocytes collected from normal individuals and cancer patients were carried out in presence of T cell growth factor (TCGF); these cultures presented cytotoxic activity directed against different targets (lectin activated cells, autologous cancer cells, antibody coated cells and K 562). In order to study separately the different effector subpopulations, isolation of single cultured cells were performed with the help of a micropipette under microscope and monoclonal cultures were carried out in presence of TCGF. In the preliminary cytotoxic assays performed in the clones: (1) a marked activity directed against lectin targets was observed in many clones and (2) an important N K activity was exhibited by the clone 45 B9 (65% of the tested cells lysed human lymphoma K 562 cells).

Clone Cells↗
PubMed1980

Evidence for cytotoxic functions in well-defined human T cell clones.

Long-term cultures of T lymphocytes from PBL of normal individuals and cancer patients grown in presence of TCGF exhibited cytotoxic activity directed against a variety of targets. In order to separate the subpopulations responsible for the different cytotoxic activities, cultured T lymphocyte cloning was performed. Production of T cell clones were obtained at a high yield by direct isolation and culture of single T cells. Preliminary analysis of cell-mediated cytotoxicity showed that 8 out of 11 clones were cytotoxic against both PHA pretreated L1210 and K562 target cells. In addition, within a clone, only a percentage of cells expressed the cytotoxic function. We suggested that this finding is due to the different stage of maturation of the cloned cells and this hypothesis correlate with their morphology, which is not identical for all the cells within a clone.

Animals↗
PubMed1979

[Identification of cytotoxic cells responsible for lysis of target cells pretreated with concanavalin A in spleen populations of pregnant mice with suppressive activity].

During an alloimmunization, killer cells which lyse target cells only in the presence of a lectin are generated. That these cells, as well as suppressive cells, share immunocytological properties with specific killer cells, leads to the hypothesis that these cells may be concerned with the mechanism of immunosuppression. Two experimental results presented in this paper are consistent with this hypothesis: 1) Spleens from H-2k mice pregnant by H-2d males which bear a high suppressive activity also contain a relatively large number of killer cells having the ability to lyse Concanavalin A treated target cells and 2) supernatants of suppressive systems generated through an MLC block the cytolysis of specific target cells by the bound killer cells.

Animals↗
PubMed1979

[Cytolysis through cells dependent on immunization against cellular antigens: identification and enumeration of cytotoxic cells].

In this report we show how to identify and enumerate alloantigen-dependent killer cells. Individual effector cells are associated by micromanipulation to target cells and the doublets are incubated at 37 degrees C. Killers are identified by the lysis of the associated target. Killer cells can be subdivided into two subpopulations: cell responsible for the lysis of the specific target cells which bear the immunizing H-2 antigens and cells which kill only lectin pretreated targets.

Animals↗
PubMed1979

[Is the process of localized lysosomal exocytosis responsible for the cytolytic action of killer T-lymphocytes?].

In this paper, we formulate the hypothesis that in the process of target cell lysis a lysosomal enzyme regurgitation, performed by killer cells at the level of the target effector junction, accounts for the target lesion which precedes the lysis (lethal hit). This process of exocytosis, similar to the one described previously in polymorphonuclear neutrophils is supported by cytological studies performed directly on identified killers isolated by micromanipulation. Light and electron microscopy observations confirm a previous report which describes the effector cells rich in lysosomal bodies. In addition, when a killer cell is associated with a target cell to form a conjugate, lysosomes are concentrated near the cell junction and, after incubation at 37 degrees C, acid phosphatases may be detected at the junction. Lysosomal enzyme exocytosis explains why target lysis needs an effector target binding to occur and also the other conditions required for any exocytosis process such as Ca++ in the medium, integrity of the microtubular apparatus, a low level of cyclic AMP and energy dependancy.

Acid Phosphatase↗
PubMed1979

Anti-peroxidase antibody-secreting hybrid lines. I. Identification, cloning and cell characterization.

Anti-peroxidase antibody (Ab)-secreting hybrids have been produced by fusion of peroxidase (PO)-immunized mouse lymph node cells and immunoglobulin (Ig)-secreting P3-X63-Ag8 (X63) myeloma cells. Identification of Ab-secreting hybrids can be performed as early as day 5 after cell fusion by the hemolytic plaque assay. Immediately after identification, hybrids were directly isolated, by means of a micropipette, into Terasaki microchambers containing nutrient medium and a thymocyte filler layer. The yield of secreting hybrids is improved by using this procedure. All the cells of the PO 772 C2 clone show the same ultrastructural pattern and immunocytological properties; they are proplasmocytes, as are the parental X63 cells; they present intracisternae Ab and show no Ig or Fc receptors at the cell surface. Over 90% of viable PO 772 C2 cells form specific plaques. Isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis show that the cells of this clone secrete Ab; the secreted Ig are formed with chi and gamma 1 chains from the parental X63 cells and specific L and H chains from the lymphoid parent. These biological investigations demonstrate the relative stability of the PO 772 C2 clone secreting anti-peroxidase antibody.

Animals↗
PubMed1979

[Cell mediated cytolysis: identification, enumeration and characterization of killer cells].

Killer cells responsible of the cell mediated cytolysis are identified by a microtechnique: effector cells are individually associated to target cells and incubated at 37 degrees C; killers are identified by their associated target lysis. Thus killer cells are enumerated in the effector cell suspensions. Furthermore, isolated killer can be characterized and their lethal action studied.

Animals↗
PubMed1979

Subpopulations of Ig-secreting cells induced by peroxidase immunization: discrimination according to antibody storage and secretion.

Mice were injected in their hind footpads with peroxidase (PO) emulsified in Freund's complete adjuvant. The development of cells secreting anti-peroxidase antibody (Ab) and cells secreting immunoglobulins (Ig) were detected in the draining popliteal lymph nodes in the subsequent 35 days, using local haemolysis plaque assay with sheep red cell blood cells coated with either PO or anti-mouse Ig antibody. Plaque-forming cells (PFC) were isolated from the centre of plaques by micromanipulation and after appropriate treatment, were examined by electron microscopy for their intracellular Ab content and in corporation of [3H]-thymidine. Four subpopulations of Ig secreting cells were distinguished: (1) cells secreting Ig without Ab function and not containing intracellular Ab detectable between days 5 and 20; (2) cells secreting Ig without Ab function but containing Ab appearing on day 6 and present throughout the immune response; (3) cells secreting Ab and containing Ab; (4) cells secreting Ab, but without detectable intracellular Ab. These last subpopulations appeared on day 7 and were found in all subsequent assays. The analysis of the kinetics of these subpopulations suggest that cells secreting Ig without Ab function might be precursors of Ab secreting cells.

Animals↗