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Biomedical subjects

D Santoli

Publications and source records attributed to D Santoli.

At least 73 records · Page 4Linked to original sources
PubMed1986

A suppressor lymphokine produced by human T leukemia cell lines. Partial characterization and spectrum of activity against normal and malignant hemopoietic cells.

Human T leukemia cell lines spontaneously release into their medium a suppressor lymphokine, T leukemia-derived suppressor lymphokine (TLSL), able to inhibit proliferation, DNA synthesis, and colony formation in a variety of malignant hemopoietic cell lines, as well as in normal myelomonocytic progenitor cells from bone marrow and peripheral blood. Titration curves indicated that the inhibitory activity in the crude supernatant preparations ranged from 10(-3)-10(-9): the supernatants from CCRF/CEM, HUT-78, and MOLT-4 cell lines were the most active, those from HPB-ALL, JM, and CCRF/HSB2 displayed an intermediate activity, and the Jurkat supernatant was the least active. Target cell lines of B cell origin (Burkitt lymphomas) were more sensitive than granulocytic, monocytic, erythroid, and T cell lines. Partial purification by ammonium sulfate precipitation and column chromatography demonstrated that TLSL is a protein with an Mr of 88,000, as determined by gel filtration. A high Mr form (greater than 300,000) was produced in serum-free medium by one of the most active producer cell lines (CCRF/CEM), and appeared to be an aggregate of the 88,000 Mr form. Neither the partially purified fractions obtained nor the crude supernatant preparations displayed antiviral activity or contained interleukin 2. Unlike lymphotoxin and tumor necrosis factor, TLSL is cytostatic: maximal inhibition of proliferation was observed 4-5 d after addition of crude supernatant to the target cells, and was not accompanied by a significant loss in cell viability. The antiproliferative capacity of TLSL was manifested both in suspension and methylcellulose cultures. Treated target cells accumulated either in the G1 or in the S phase of the cell cycle. The effect of TLSL on the target cells is irreversible: even brief (1 h) incubation of sensitive cells with TLSL resulted in inhibition of proliferation measured 5 d later. Although TLSL is produced by leukemic T cell lines, this lymphokine inhibits proliferation of normal peripheral blood T cells in response to mitogens or alloantigens: T lymphocyte activation was inhibited by all of the T cell supernatants tested. In contrast, when T cell lines were used as targets, no inhibition of proliferation was detected with two exceptions: the low producer Jurkat cell line was sensitive to all the T cell-derived supernatants, and the intermediate producer CCRF/HSB2 cell line was sensitive only to the three most active supernatants, CCRF/CEM, MOLT-4, and HUT-78. The possible significance of TLSL and its relationship with other suppressor lymphokines previously described in other systems is discussed.

Cell Cycle↗
PubMed1985

Generation of natural killer-like activity in mixed lymphocyte-tumor cell cultures. II. Correlation between expression of HLA-DR antigens on the activated T cells and their cytotoxic capability.

In this study, we investigated the role of DR antigens in human mixed lymphocyte reactions (MLR) at the responder cell level. Upon stimulation by allogeneic lymphocytes or leukemic cell lines, a large proportion of T cells underwent blastogenesis and began expressing DR antigens. Analysis by a fluorescence-activated cell sorter revealed that both subpopulations of large activated T cell blasts and of small T lymphocytes became DR+ by synthesis and/or uptake. Depletion of DR+ responder cells from 6-day-old MLRs by treatment with anti-DR monoclonal antibodies (mAbs) plus complement (C) reduced but did not completely abrogate the natural killer (NK)-like activity of the responder lymphocytes, suggesting that the MLR-induced cytotoxic cells include both DR+ and Dr- populations. The expression of NK-like activity by the responder cells was also greatly reduced upon addition of anti-DR mAbs (without C) at the start of the mixed cultures. This effect was observed regardless of the presence of DR antigens on the stimulator cells, indicating that the anti-DR mAbs can interact with the antigens present on both the stimulator and responder populations. These data show that during an MLR, the continued presence of DR antigens on the responding population is essential for the expression and maintenance of the proliferative and cytotoxic capabilities of these cells.

Antibodies, Monoclonal↗
PubMed1985

Generation of natural killer-like activity in mixed lymphocyte-tumor cell cultures. I. Role of HLA-DR antigens as stimulatory molecules.

A number of human lymphoid and non-lymphoid leukemic cell lines differing for expression of HLA-DR antigens were analyzed for the ability to induce natural killer(NK)-like activity and proliferation in lymphocytes from healthy donors. The ability to elicit the generation of NK-like activity in the responder lymphocytes varied greatly depending upon the type of antimitotic treatment (gamma-irradiation versus mitomycin C) received by the tumor cells prior to the start of the mixed cultures. By contrast, the induction of T-cell proliferation was positively correlated with the presence of DR molecules on the tumor cell lines. Nevertheless, DR- leukemic cells pretreated with the appropriate antimitotic agent did induce a proliferative response in the mixed cultures. T lymphocytes cultured without stimulator cells in spent medium containing high levels of cell-free DR antigens failed to undergo blastogenesis and proliferation, indicating that DR antigens can function as stimulatory molecules only when they are cell-associated.

Cell Line↗
PubMed1984

Phenotypic and functional characterization of T cell clones derived from the cerebrospinal fluid of multiple sclerosis patients.

We describe here T cell cultures and clones established from the cerebrospinal fluid (CSF) of three patients with multiple sclerosis (MS) and one chronic meningitis patient with pleocytosis. Most of the cultures were activated with phytohemagglutinin (PHA) before growth in mitogen-free interleukin 2 (IL 2), and were never restimulated. Some of the clones obtained have been propagated for over 1 yr and are strictly IL 2-dependent. Immunofluorescence analysis performed with various monoclonal antibodies revealed that the CSF-derived lines had the characteristics of activated T cells with a stable expression of either suppressor/cytotoxic or helper/inducer surface antigens. Most of the clones established had a predominantly suppressor phenotype (OKT8+), except for the clones derived from one MS patient, which expressed only the helper phenotype (anti-Leu-3a+). Consistent with these data, the CSF-derived cultures displayed a variety of immunoregulatory functions, such as the ability to lyse nonspecific and PHA-stimulated target cells, to produce IL 2 upon mitogenic activation, and to modulate polyclonally induced Ig responses. The availability of long-term CSF T cell cultures derived from MS patients at various disease stages might provide a useful tool in investigating the factor(s) involved in the etio-pathogenesis of the disease.

Adolescent↗
PubMed1983

Induction of proliferation and NK activity in human lymphocytes by mature myelomonocytic cells: evidence for an HLA-DR-independent MLR stimulatory ability of terminally differentiated nonlymphoid leukemic cell lines and of normal peripheral blood granulocytes.

Three human myeloid leukemic cell lines (HL60, KG1, and ML3) and one histiocytic lymphoma line (U937) were induced to differentiate terminally to mature myelomonocytic cells with either 12-O-tetradecanoylphorbol-13-acetate (TPA) or lymphocyte-conditioned medium (LCM), which is known to contain differentiation-inducing factors. HL60 cells were also forced to differentiate along the myeloid series with retinoic acid (RA) or dimethyl sulfoxide (DMSO). The striking morphologic changes and the expression of differentiated markers on the induced cells (whether macrophage- or granulocyte-like) were always associated with an acquired or dramatically increased ability to stimulate proliferation and natural killer cell (NK) activity in human lymphocytes. Like HL60 cells after granulocytic differentiation, granulocytes freshly separated from the peripheral blood of healthy donors were also strong inducers of mixed lymphocyte reaction (MLR) responses. Analysis of the expression of HLA-DR antigens on the surface of undifferentiated and mature cells with two monoclonal antibodies directed against HLA-DR monomorphic determinants, indicated that 1) upon differentiation induced with RA, DMSO, and TPA the cells never acquired surface DR antigens, and 2) normal peripheral blood granulocytes lacked these antigens. In contrast, treatment with LCM always resulted in the expression of high levels of DR antigens on the differentiated macrophage-like cells. Taken together, these findings indicate that all mature myelomonocytic cells, either freshly separated from peripheral blood or obtained after forced in vitro differentiation of leukemic cells, express MLR stimulatory antigens that appear to be unrelated to DR determinants. The possibilities discussed are that such antigens are associated with other molecules encoded by the D region or with new surface structures unrelated to Ia but dependent on the stage of differentiation.

Cell Differentiation↗
PubMed1981

Cytotoxic activity and interferon production by lymphocytes from patients with multiple sclerosis.

Peripheral blood lymphocytes from MS patients and from healthy control donors were compared for their ability to mediate spontaneous and antibody-dependent cell-mediated cytotoxicity. They were also compared for their ability to respond to infection with various strains of measles and sSPE viruses with interferon production and enhanced NK activity. Neither SLMC nor ADCC against several different target cells was found to be impaired in the MS population. Furthermore, no defect was detected in the response of patients' lymphocytes to virus challenge in vitro in terms of both activation of NK cells and interferon production. Enhanced NK activity was also induced by an exogenous interferon preparation and by Poly I:C to the same extent in patients and controls.

Adult↗
PubMed1981

Antagonistic effects of interferons on the cytotoxicity mediated by natural killer cells.

Human interferons (IFs) can induce a several-fold increase in the natural cytotoxicity of human lymphocytes on target cell lines. IFs increase the efficiency of cytotoxicity and the number of natural killer (NK) cells. In mixed cultures of lymphocytes and other tumor-derived or virus-infected cells, endogenous IF is produced, which mediates 70-90% of the observed cytotoxicity. The effect of IF on target cells is antagonistic to its effect on lymphocytes: the susceptibility to lysis of cells treated with IF decreases. Whereas normal fibroblasts are protected by IF, virus-infected cells and most tumor-derived cells are not. The protective effect is specific for NK cells cytotoxicity: IF-treated target cells are lysed to the same extent as the untreated controls by antibody-dependent killer cells, by phytohemagglutinin-stimulated lymphocytes, by cytotoxic T lymphocytes, and by antibodies and complement. NK cells bind to IF-treated fibroblasts, but are unable to lyse them. The cytotoxic ability of NK cells is inactivated after interaction with normal fibroblasts, but not with IF-treated fibroblasts. Unlabeled, normal fibroblasts but not IF-treated fibroblasts compete for the cytotoxicity mediated by NK cells in 51Cr-labeled target fibroblasts. IF, by stimulating very efficient, nonspecific cytotoxic cells, and by protecting normal cells from lysis, might render the NK cell system an inducible defense mechanism against virus-infected and tumor cells.

Cell Line↗
PubMed1979

Human promyelocytic leukemia cells in culture differentiate into macrophage-like cells when treated with a phorbol diester.

When suspension cultures of human promyelocytic leukemia cells (line HL60) were treated with 12-O-tetradecanoylphorbol 13-acetate (TPA; 1.6-160 nM), more than 80% of the cells adhered to the plastic substrate within 24 hr. Within the same time period the immature azurophilic granulations typical of HL60 promyelocytic cells disappeared and the nuclear chromatin became more condensed, but the nucleolus was retained. The attached cells stopped dividing and synthesizing DNA. The phenomenon was irreversible and independent of the continuous presence of TPA. Approximately 60% of the untreated cells and of TPA-treated cells bore surface Fc receptors for IgG. Under the experimental conditions used, about 10% of the TPA-treated cells were also able to phagocytize IgG-coated erythrocytes and more than 80% were able to phagocytize latex beads, but untreated controls were unable to do so. Cellular levels of NADase, acid phosphatase, and non-specific esterase were markedly increased after treatment with TPA, whereas little or no increase was seen after treatment with dimethyl sulfoxide (Me2SO), a drug that induces myeloid differentiation of HL60 cells. Peroxidase activity was lower in TPA-treated and Me2SO-treated cells than in HL60 cells. More lysozyme was found in the medium of TPA-treated cells than in the medium of untreated or Me2SO-treated cells. These data indicate that, after treatment with TPA, human promyelocytic leukemia cells can differentiate into cells that have several characteristics of macrophages.

Cell Adhesion↗
PubMed1979

Human T-lymphocyte subpopulations: alterations in systemic lupus erythematosus.

Sharply reduced proportions of T cells with Fc receptors for IgG (TG cells) were observed in blood samples from patients with systemic lupus erythematosus (SLE), mainly with active disease. This T-cell subset has previously been shown to be a suppressor in the pokeweed mitogen (PWM)-dependent B-cell differentiation. In contrast, the percentages of T cells with Fc receptors for IgM (TM cells), which have been shown to help immunoglobulin production, were not different from those of normals. TG cells present in the circulation of SLE patients were analysed for their functional capacities in antibody-dependent cell-mediated cytotoxicity and in the suppression of a PWM-induced B-cell differentiation. In both these assays TG cells from SLE patients had normal effector cell activity. This suggests that thr than a qualitative type.

Adolescent↗
PubMed1978

Anti-viral activity induced by culturing lymphocytes with tumor-derived or virus-transformed cells. Identification of the anti-viral activity as interferon and characterization of the human effector lymphocyte subpopulation.

A viral inhibitor(s) is released in the supernate of mixed cultures containing human or mouse lymphocytes and cells from certain lines. The inhibitor is active against a variety of unrelated viruses and is a protein that is not toxic for cells. It does not inactivate viruses directly, but inhibits viral replication through an intracellular mechanism that involves synthesis by the cells of both RNA and protein. These characteristics identify the inhibitor as an interferon. The anti-viral activity is contained in at least two molecular species, of approximately 25,000 and 45,000 daltons, respectively. In addition to the anti-viral activity, the supernates of the mixed cultures display an anti-cellular activity, the inhibition of DNA synthesis and of cell multiplication. The anti-viral and the anti-cellular activities are positively correlated in supernates from various cultures and in partially purified preparations. The human cell population responsible for interferon production is composed mainly of Fc-receptor positive, surface immunoglobulin negative, non-T-cell lymphocytes. The ability of certain cell lines to induce interferon seems to be preferentially associated with tumor origin or with in vitro transformation by certain viruses (Epstein-Barr virus, murine sarcoma virus).

Animals↗
PubMed1978

Anti-viral activity induced by culturing lymphocytes with tumor-derived or virus-transformed cells. Enhancement of human natural killer cell activity by interferon and antagonistic inhibition of susceptibility of target cells to lysis.

Interferon, induced in lymphocytes either with viruses or cell lines, increases severalfold the natural cytotoxicity of human lymphocytes on target cell lines. Cell separation experiments support the hypothesis that interferon enhances the activity of natural killer cells rather than generating a new population of effector cells. In mixed culture of lymphocytes and cell lines in which endogenous interferon is produced, interferon mediates an enhancement of cytotoxicity that represents up to 70-90% of the observed cytotoxicity. The effect of interferon on target cells is antagonistic to the effect on the lymphocytes: the susceptibility to cell-mediated lysis of various cells upon pretreatment with interferon is decreased and in some cases almost completely suppressed. Interferon renders target cells resistant to natural killer cells acting by an intracellular mechanism which requires RNA and protein synthesis. While normal fibroblasts are protected, virus-infected cells and most tumor cells usually are not protected by interferon. Interferon by stimulating very efficient nonspecific cytotoxic cells and by protecting at the same time normal cells from lysis, might render the natural killer cell system an inducible selective defense mechanism against tumor and virus-infected cells.

Animals↗
PubMed1978

Cell-mediated cytotoxicity against virus-infected target cells in humans. II. Interferon induction and activation of natural killer cells.

The mechanisms by which human lymphocytes lyse virus-infected allogeneic fibroblast cultures were analyzed with particular consideration of the role of anti-viral antibodies and interferon. Human cells infected with viruses were able to induce high levels of interferon upon contact with human lymphocytes. Interferon, whether produced by lymphocytes after direct infection with virus or induced upon exposure of lymphocytes to virus-infected fibroblasts, appeared to be responsible for enhancing the cytotoxic efficiency of the natural killer cell against the infected target. Activation of cytotoxic lymphocytes occurred as early as 6 hr after addition of interferon and increased up to 24 hr. Antibody-dependent cell-mediated cytotoxicity (Ab-CMC) could be easily induced by sensitization of infected target cells with antiviral antibodies and could be detected at 4 hr from the beginning of the cytotoxic test, before the effect of interferon on the natural killer cell was evident. However, the antibody-dependent effector cell was inactive after 4 hr of incubation. F(ab')2 fragments of rabbit anti-human IgG completely inhibited Ab-CMC but did not at all affect the spontaneous cytotoxic activity of the effector cells against virus-infected target.

Cytotoxicity, Immunologic↗
PubMed1978

Imbalances in T cell subpopulations in multiple sclerosis patients.

Abnormal proportions of a distinct T cell subpopulation able to bind IgG immune complexes (T.G cells) were found in peripheral blood samples from patients with MS. About 50% of the patients examined had an overabundance of T.G cells. The possible role of these cells in the pathogenesis of MS is considered.

Blood Cell Count↗