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Biomedical subjects

G F Burns

Publications and source records attributed to G F Burns.

At least 55 records · Page 3Linked to original sources
PubMed1989

Regulation of expression of a human intercellular adhesion molecule (ICAM-1) during lymphohematopoietic differentiation.

The intercellular adhesion molecule (ICAM-1) is a cell-surface molecule which binds to leukocyte function antigen-1 (LFA-1) and regulates both leukocyte adhesion to endothelial cells and immune functions requiring cell-cell contact. Membrane expression of ICAM-1 is highly regulated on all hematopoietic lineages. Cell membrane antigen is significantly expressed on a small subset of bone marrow (BM) progenitors but is weak or absent on all cell lineages once they enter the circulation. However, strong expression on tissue macrophages and germinal center B cells suggested that activated cells may show upregulated expression. When B cells, T cells, macrophages, or granulocytes were activated in vitro by suitable mitogens, ICAM-1 expression was induced in all cases. Parallel studies of hematopoietic tumors demonstrated a heterogeneity of expression which correlated with expression on their normal cellular counterparts. In particular, a striking correlation between expression on B-cell tumors and corresponding stages of B-cell differentiation was noted. The widely varying expression of ICAM-1 contrasts with LFA-1 which, while variable, is nevertheless significantly positive at all stages of differentiation. This suggests that the major regulation of homotypic adhesion mediated by the LFA-1/ICAM-1 linkage occurs through control of ICAM-1 expression. In keeping with this notion, ICAM-1 expression was also correlated with the "adhesiveness" of B-lymphoid tumors. Large solitary lymphoma masses showed intense expression of ICAM-1. Conversely, chronic lymphocytic leukemia (CLL) cells and lymphoma cells from tumors exhibiting diffuse, widespread lymph node disease showed weak expression. These observations are discussed in relation to the role of ICAM-1 in regulation of lymphoid recirculation and the biology of lymphoid tumors.

Animals↗
PubMed1989

Human interleukin 4 regulates the phenotype of lymphocytes generated during mixed lymphocyte culture and inhibits the IL-2-induced development of LAK function in normal and leukaemic cells.

This study examined the immunoregulatory role of recombinant interleukin 4 (IL-4), also known as B-cell stimulating factor 1, on the generation of cytotoxic effector cells from normal and leukaemic human blood mononuclear cells. When tested on cells from normal individuals, the addition of IL-4 to mixed lymphocyte cultures led to a dose-dependent proliferation of T-helper cells (CD3, 4 positive) with a concomitant decrease in phenotypic and functional cytotoxic T cells and natural killer (NK) cells. IL-4 also inhibited the interleukin-2 (IL-2)-induced generation of lymphokine-activated killer (LAK) activity when added at the beginning of mixed lymphocyte culture. When tested on mature leukaemic NK cells, IL-4 also inhibited the ability of IL-2 to induce LAK function using a short-term culture system. These results show that IL-4 acts on both normal and leukaemic cells and suggests that it acts at more than one level during the development of LAK function.

Antigens, Differentiation↗
PubMed1989

TGF beta down-regulates TLiSA1 expression and inhibits the differentiation of precursor lymphocytes into CTL and LAK cells.

This study analysed the regulatory effects of transforming growth factor beta (TGF beta) on the expression of a 70,000 MW cell surface activation antigen, TLiSA1, involved in the differentiation of cytotoxic T lymphocytes (CTL) and lymphokine-activated killer (LAK) cells from their precursor(s), and also examined the role of TGF beta in the generation of these functional cells. TGF beta was shown to suppress the expression of TLiSA1 and to inhibit, in a dose-dependent manner, the generation of both CTL and LAK cells when present from the beginning of mixed lymphocyte culture; the same inhibitory effect upon the development of cytotoxic effector cells was observed with a monoclonal antibody and with monospecific rabbit antibodies against the TLiSA1 protein. Antibody to TGF beta reversed the inhibitory effect of the cytokine on differentiation and on TLiSA1 expression. Exogenous IL-2 or, to a lesser extent, tumour necrosis factor alpha (TNF alpha) added to mixed lymphocyte cultures (MLC) augmented both TLiSA1 antigen expression and cytotoxic function by the resulting blast cells; the co-addition of TGF beta inhibited both of these cytokine-mediated effects. Similarly, it was shown that phytohaemagglutini (PHA)-induced lymphoblasts up-regulate their surface expression of TLiSA1 and exhibit increased LAK activity in response to IL-2, and TGF beta inhibited both of these events; this IL-2-induced increase in LAK cell function was also inhibited by antibodies to TLiSA1. It is suggested that TLiSA1 antigen expression is intimately linked to the differentiation of cytotoxic effector cells and that such differentiation may be a distinct process from IL-2-induced proliferation, although both events can be regulated by TGF-beta.

Antigens, Surface↗
PubMed1988

Evidence for interactions between monocytes and natural killer cells in the regulation of in vitro hemopoiesis.

The role of accessory cells in modulation of in vitro hemopoiesis was studied using C-mediated lysis with mAb of differing specificities. One such antibody, 25E11, which bound to all NK cells and a subset of monocytes, consistently led to enhancement of in vitro hemopoiesis when 25E11+ cells were depleted by complement or the FACS. In cultures maximally stimulated by erythropoietin and human placental conditioned medium, depletion of 25E11+ cells from beta-thalassemic PBMC resulted in up to a fourfold enhancement of multi-potential and pure erythroid colonies and a twofold enhancement of non-erythroid colonies when compared with C-only treated cells. This enhancement of in vitro hemopoiesis was also observed with cells from normal bone marrow, cord blood, and peripheral blood. The enhancement of in vitro hemopoiesis was abrogated by removal of either adherent cells or monocytes using Leu M3 antibody and C lysis. The data presented herein suggest that NK cells and a subset of monocytes may exert a negative regulatory control on both granulopoiesis and erythropoiesis. Consequently, the number of progenitor and multipotential cells in cultures of unfractionated cell populations may be greatly underestimated.

Adult↗
PubMed1988

Intercellular adhesion molecule 1 (ICAM-1) has a central role in cell-cell contact-mediated immune mechanisms.

The role of intercellular adhesion molecule 1 (ICAM-1) in immune function was probed by using the Wehi-CAM-1 (W-CAM-1) monoclonal antibody. This antibody blocks aggregation of cell lines mediated by the ICAM-1 molecule and is here shown to block homotypic binding of purified populations of activated T and B lymphocytes (blasts) and also aggregation of mixed T- and B-cell blasts. We also demonstrate that W-CAM-1 inhibited T-cell adhesion to normal human endothelial cells, the first step in lymphocyte egress into the tissues. In tests of immune function, W-CAM-1 had a modest inhibitory effect on T- and B-cell activation by potent mitogens and no effect on the response of activated lymphocytes to lymphokines. By contrast, activation induced by cell-cell contact (mixed lymphocyte reaction, T-cell-mediated B-cell activation) was significantly inhibited. Moreover, the antibody was shown to block elements of both effector arms of the immune system (cytotoxic cell function and immunoglobulin production). These findings show that the ICAM-1 molecule is a central component of the mechanism of lymphocyte-endothelial cell adhesion. The studies of lymphoid function demonstrate a pivotal role for this molecule in both the T-cell/T-cell and T-cell/B-cell interactions, which underpin the regulation of the immune response, and in the mechanism of cell-mediated cytotoxicity.

Antibodies, Monoclonal↗
PubMed1988

Synergism between membrane gangliosides and Arg-Gly-Asp-directed glycoprotein receptors in attachment to matrix proteins by melanoma cells.

The identification of specific cell surface glycoprotein receptors for Arg-Gly-Asp-containing extracellular matrix proteins such as fibronectin has focused attention on the role of gangliosides in this process. Is their involvement dependent or independent of the protein receptors? In attachment assays with cells from a human melanoma cell line, titration experiments with an antibody (Mel 3) with specificity for the disialogangliosides GD2 and GD3, used together with a synthetic peptide containing the cell binding sequence Arg-Gly-Asp, show that their joint effect is synergistic. Both the Mel 3 antibody and the synthetic peptide individually cause rapid detachment of melanoma cells from fibronectin substrate but, when used together, much smaller concentrations of both are required to achieve the same effect. The Mel 3 antibody was not nonspecifically reducing receptor binding to the Arg-Gly-Asp sequence since, in binding assays with radiolabeled peptide performed with cells in suspension, very little peptide is bound by the melanoma cells under these conditions but addition of Mel 3, an antibody of IgM isotype, causes a two- to threefold increase in specific binding. The simplest interpretation of these data is that the Mel 3 antibody is causing sufficient clustering of membrane gangliosides in local areas and producing a favorably charged environment to facilitate peptide binding by specific glycoprotein receptors.

Antibodies, Monoclonal↗
PubMed1988

Synovial fluid neutrophils of patients with rheumatoid arthritis have membrane antigen changes that reflect activation.

The level of expression of surface antigens was studied on neutrophils from paired samples of blood and synovial fluid of patients with rheumatoid arthritis (RA). By measuring the immunofluorescence of labelled monoclonal antibodies it was shown that on joint neutrophils there was an increase in expression of complement receptor 3 (CR3) and granulocyte functional antigens 1 and 2 compared with blood neutrophils, whereas the expression of GpIIb-IIIa was reduced. The pattern of expression was the same as that seen with in vitro activation and strongly suggest that activation is occurring within the joint.

Antigens, Surface↗
PubMed1988

Activated killer cell lymphoma: an erythrophagocytic syndrome simulating histiocytic medullary histiocytosis.

We report a detailed analysis of a lymphoma-induced erythrophagocytic syndrome mimicking histiocytic medullary reticulosis. Phenotypic analysis of cell surface molecules demonstrated a T cell-like phenotype. However, more extensive analysis showed that this phenotype was not typical of any element of the normal T cell lineage. The markers were consistent with a subset of natural killer cells, the lymphokine-activated killer (LAK) cell. The lymphoma cells, like normal LAK cells, were shown to be capable of non-specific cytotoxicity. Moreover, consistent with the reported regulatory effects of certain non-specific killer cells on hemopoiesis, the lymphoma cells were able to suppress in-vitro hemopoiesis, especially maturation of erythroid precursors, although a soluble factor could not be directly demonstrated. Both of these activities were blocked by a monoclonal antibody (9.IC3) which inhibits NK cell function. These findings imply that this tumour is a neoplastic counterpart of the cell identifiable in vitro as an LAK cell.

Antibodies, Monoclonal↗
PubMed1988

Recombinant human granulocyte-macrophage colony-stimulating factor (rH GM-CSF) regulates f Met-Leu-Phe receptors on human neutrophils.

The regulation of mature human neutrophil function by recombinant human granulocyte-macrophage colony-stimulating factor (rH GM-CSF) was studied. Preincubation of neutrophils with this CSF did not stimulate superoxide anion directly but enhanced the subsequent release of superoxide anion in response to stimulation with the bacterial product formylmethionylleucyl-phenylalanine (f Met-Leu-Phe). Enhanced superoxide anion production was evident by 5 min and reached a plateau at 30 min. In contrast, neutrophils preincubated with rH GM-CSF exhibited reduced chemotaxis under agarose in response to a gradient of f Met-Leu-Phe. The inhibition of neutrophil migration was dependent on the dose of rH GM-CSF and exhibited a time-course similar to the effect on superoxide production. Binding studies of f Met-Leu-[3H]Phe to purified human neutrophils revealed heterogeneous binding to unstimulated cells. Two affinity components were identified. The high-affinity component consisted of approximately 2000 sites/cell and had an average Kd of 4 +/- 2 nM (n = 6). The low-affinity component consisted of approximately 40,000 sites/cell and had an average Kd of 220 +/- 130 nM (n = 6). rH GM-CSF caused conversion to a linear Scatchard plot showing no significant change in total binding sites but a single Kd of 30 +/- 10 nM. These data indicate that rH GM-CSF may influence neutrophil responses to f Met-Leu-Phe by regulating the affinity of f Met-Leu-Phe receptors.

Chemotaxis, Leukocyte↗
PubMed1988

Enhancement of in vitro beta-thalassemic and normal hematopoiesis by a noncytotoxic monoclonal antibody, 9.1C3: evidence for negative regulation of hematopoiesis by monocytes and natural killer cells.

The enhancement of in vitro human hematopoiesis by the addition of a noncytotoxic monoclonal antibody, 9.1C3, is described. Enhancement of all aspects of in vitro hematopoiesis was observed on addition of 9.1C3 antibody to cultures of mononuclear cells from normal bone marrow, cord blood, and peripheral blood from beta-thalassemia major patients. In cultures with no exogenous colony-stimulating factor (CSF), the addition of 9.1C3 resulted in a two- to eightfold increase in nonerythroid colony formation. Similarly, for cultures maximally stimulated with CSF, the addition of 9.1C3 antibody resulted in a one- to fourfold increase in colony formation. These effects were abrogated by the removal of either adherent, Leu-M3+ or Leu-7+ cells. Colony-forming cells were shown to be present among the 9.1C3-negative cells when mononuclear cells were sorted by flow cytometry. Media conditioned in the presence of 9.1C3 and mononuclear cells were able to enhance colony formation in vitro for normal nonadherent bone marrow cells beyond that achieved with supramaximal amounts of human placental-conditioned medium and erythropoietin. The data suggest that natural killer cells interact with monocytes to exert a negative regulatory control on in vitro granulopoiesis and erythropoiesis. Consequently, the number of progenitor and multipotential cells in cultures of unfractionated cell populations may be greatly underestimated.

Adjuvants, Immunologic↗
PubMed1987

Monoclonal antibody Leo Mel 3, which inhibits killing of human melanoma cells by anomalous killer cells, binds to a sugar sequence in GD2 (II3(NeuAc)2-GgOse3Cer) and several other gangliosides.

Human anomalous killer (AK) cells lyse freshly isolated human melanoma cells which are insensitive to human natural killer cell-mediated lysis. Monoclonal antibody Leo Mel 3, an IgM (k), produced by a hybridoma obtained from a mouse immunized with human melanoma cells, binds to melanoma cells and inhibits their conjugate formation with AK cells as well as their AK cell-mediated lysis. Other IgM antibodies from the same fusion that bind melanoma cells do not inhibit (Werkmeister, J. A., Triglia, T., Andrews, P., and Burns, G. F. (1985) J. Immunol. 135, 689-695). Leo Mel 3 binds several different gangliosides from melanoma cells, as determined by immunostaining thin layer chromatograms. Binding is abolished by treatment of the gangliosides with neuraminidase. In solid-phase radioimmunoassay, Leo Mel 3 binds strongly to ganglioside GD2 and less strongly to gangliosides GT3, GD3, and GQ1b. It does not bind to other gangliosides including GM1, GM2, GM3, GD1a, GD1b, and GT1b. Thus, the epitope recognized by antibody Leo Mel 3 is found in the sugar sequence of ganglioside GD2, GalNAc beta 1-4[NeuAc alpha 2-8NeuAc alpha 2-3]Gal beta 1-4Glc beta 1 .... This sequence may contain a target in melanoma cells recognized by AK cells.

Antibodies, Monoclonal↗
PubMed1987

Fluctuations in the expression of a glycolipid antigen associated with differentiation of melanoma cells monitored by a monoclonal antibody, Leo Mel 3.

A monoclonal antibody, Leo Mel 3, raised against a melanoma cell line (LiBr), binds to a carbohydrate determinant of cell surface gangliosides, the simplest of which is GD3. This monoclonal antibody was screened for by its capacity to block the recognition and lysis of the melanoma cells by cytotoxic T-lymphocytes with anomalous killer cell function, illustrating a novel approach for identifying monoclonal antibody to biologically relevant tumor-associated antigens. Leo Mel 3 reacted selectively with melanoma cells by indirect immunofluorescent and immunoperoxidase staining; it reacted with tissue from all primary and metastatic melanoma tested, and it bound to cells from all but one of six cultured melanoma cell lines. Leo Mel 3 did not react with a variety of carcinomas, lymphomas, leukemias, and other neuroectodermal tumors, nor with adult or fetal tissues, except fetal liver. Very weak staining of cutaneous basal melanocytes was noted in a minority of skin sections, and 50 to 80% of melanocytes in four of seven benign nevi showed weak to moderate reactivity. The antibody was relatively specific for human adherent melanoma cells, since it did not bind to the adherent murine B16 melanoma line nor to a nonadherent human melanoma cell line (PMC-22). Expression of the Leo Mel 3-defined antigen was unrelated to changes in cell cycle. When cells from an adherent melanoma cell line were detached and maintained briefly in suspension culture, the cells became markedly less reactive with Leo Mel 3 and, after readherence to plastic, they rapidly reexpressed higher levels of the ganglioside antigen; since Leo Mel 3 prevented attachment and growth of melanoma cells in vitro, a functional role for the ganglioside is suggested in cell adhesion and metastasis. Differentiation of melanoma cells with dimethyl sulfoxide, retinoic acid, and theophylline resulted in a marked and selective increase in the amount of Leo Mel 3-defined antigen, together with an increase in the target cell binding ability of these cells, assessed by cold target competition assays using anomalous killer cells.

Antibodies, Monoclonal↗
PubMed1987

Stimulation of proliferation, differentiation, and function of human cells by primate interleukin 3.

Cloned gibbon interleukin 3 (gIL-3) was found to stimulate the proliferation and differentiation of human bone marrow cells to produce day-14 granulocyte, macrophage, granulocyte-macrophage, and eosinophil colonies in semisolid agar. In the presence of normal human plasma, gIL-3 stimulated megakaryocytes. In methylcellulose cultures, it stimulated erythroid colonies in the presence, but not in the absence, of erythropoietin. When mature human leukocytes were used, gIL-3 stimulated the function of purified mature eosinophils as measured by the capacity to kill antibody-coated target cells, to produce superoxide anions, and to phagocytize opsonized yeast particles in a manner similar to recombinant human granulocyte-macrophage colony-stimulating factor. In contrast, gIL-3 did not significantly stimulate any of the neutrophil functions tested, whereas human recombinant granulocyte-macrophage colony-stimulating factor was active in these assays. Among cytokines that are active on human hematopoietic cells, gIL-3 thus has a distinct set of functions and may predict the range of actions of the human molecule.

Animals↗
PubMed1986

The IIb-IIIa glycoprotein complex that mediates platelet aggregation is directly implicated in leukocyte adhesion.

Evidence is presented that the IIb-IIIa glycoprotein complex, which functions as the receptor for fibrinogen on platelets and is central to platelet aggregation, is expressed on the surface of leukocytes where it may function as a receptor for fibronectin. F(ab')2 fragments of a monoclonal antibody, 25E11, raised against activated large granular lymphocytes, inhibited killing by natural killer cells, blocked the binding of fibronectin-coated particles by monocytes, and stimulated neutrophils to exhibit increased antibody-dependent killing. Immunoprecipitation studies of leukocytes and platelets, and the ability of 25E11 to inhibit platelet aggregation, identified the antigen as an epitope on the IIb-IIIa complex. This glycoprotein thus constitutes the first example of a receptor mediating both platelet aggregation and leukocyte adhesion.

Adult↗
PubMed1986

Interferon: a cytotoxic T lymphocyte differentiation signal.

Human T cell clones which were able to proliferate in response to specific stimuli but could not kill even in the presence of lectins were found to acquire the specific lytic function when interferon alpha or gamma was added on day 1 of the 7-day restimulation culture. These results demonstrate that interferon may act as a cytotoxic T lymphocyte differentiation signal. This signal can be blocked by the monoclonal antibody LeoA1 which recognizes a 70-kDa cell surface structure, involved in cytotoxic T lymphocyte differentiation.

Antibodies, Monoclonal↗
PubMed1986

Allospecific proliferative human T-cell clones acquire the cytotoxic effector function after three months in culture, in IL-2 conditioned medium.

Allostimulated T lymphocytes were cloned by micromanipulation and expanded in IL-2 conditioned medium. Three T3+,T4+,T8-, clones called BJ1, BJ4, and BJ37, were extensively studied. The BJ1 cells were able to proliferate and kill the specific target. The BJ4 and BJ37 cells were able to proliferate with the specific restimulator but could not kill even in lectin-dependent cell-mediated cytotoxic assay; however, they acquired the specific cytolytic activity in the 6-day culture when fresh irradiated autologous peripheral blood mononuclear cells as feeder cells were added to the specific irradiated Epstein-Barr virus transformed cell line, in the presence of recombinant IL-2. This observation strongly suggested that the culture conditions could be involved in the differentiation of proliferative clones into cytotoxic T lymphocyte (CTL) clones, by the lymphokines, either present in the IL-2 conditioned medium or secreted by the mixed allogeneic irradiated feeder cells. Moreover, it was shown that the acquisition of the cytolytic function could be blocked by the monoclonal antibody LeoA1, previously described and which recognized the TLiSA1 structure involved in the CTL differentiation.

Antibodies, Monoclonal↗
PubMed1986

Cloned human cytotoxic T lymphocytes develop anomalous killer cell function.

Mixed lymphocyte cultures were set up between blood mononuclear cells and irradiated autologous or allogeneic B lymphoblasts infected with Epstein-Barr virus. The resulting cytotoxic effector cells were cloned and tested for activity against the stimulating B lymphoblast, K562 and melanoma targets. Specific clones which killed only the stimulating B lymphoblasts (cytotoxic T lymphocytes; CTL) were re-cloned and the subclones tested for cytolysis of B lymphoblasts and melanoma cells. Of seven primary CTL clones generated in allogeneic culture, 308 subclones developed the ability to kill melanoma cells and none retained specific CTL function. In the autologous system, 180 subclones were derived from three specific primary clones: of these, 13 (7%) retained specific function, 29 (16%) were able to kill both B lymphoblasts and melanoma cells, and 93 (52%) killed only the melanoma target. Testing of random clones demonstrated that whereas both B lymphoblast killing (CTL function) and melanoma cell killing (anomalous killer; AK function) were blocked by a monoclonal antibody to LFA-1, only CTL function was blocked by anti-T3 or anti-T8 antibodies. The factor(s) causing the progression of CTL to AK cells are discussed. These data thus demonstrate that the majority of CTL are capable of mediating AK cell function and are thus potentially suitable for passive immunotherapy.

Antigens↗