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Biomedical subjects

M K Gately

Publications and source records attributed to M K Gately.

At least 91 records · Page 5Linked to original sources
PubMed1988

Characterization of a factor(s) which synergizes with recombinant interleukin 2 in promoting allogeneic human cytolytic T-lymphocyte responses in vitro.

Supernatants from PHA-activated human peripheral blood mononuclear cells, depleted of virtually all IL-2 activity by an anti-rIL-2 immunoadsorbent column, contain a factor(s) which synergizes with rIL-2 in facilitating the generation of allogeneic human CTL responses in vitro. This factor, provisionally termed CTL maturation factor (TcMF), did not appear to promote CTL responses in the absence of rIL-2. Furthermore, it acted later than IL-2 in facilitating CTL responses and could not be replaced by recombinant IFN-gamma. In this report we show that rIFN-alpha, rIL-1 alpha, and rIL-1 beta likewise lack TcMF activity. The TcMF activity in lymphokine-containing culture supernatants could be eliminated by trypsin or pronase but not by neuraminidase or RNase. Gel filtration revealed two peaks of TcMF activity, one at 12,000 to 25,000 Da and the other at 45,000 to 65,000 Da. Isoelectrofocusing demonstrated substantial charge heterogeneity. The majority of TcMF activity was recovered between pI 4.0 and pI 5.5 with a minor component at pI 6.5, corresponding to the areas in which IL-1 activity was also found. However, TcMF activity could be separated from IL-1 by reverse-phase HPLC. Moreover, TcMF recovered following reverse-phase HPLC was also found to be depleted of IL-4 activity. These studies suggest that TcMF activity is mediated by a protein(s) distinct from IL-1, IL-2, IL-4, and interferon-alpha or-gamma.

Biological Products↗
PubMed1988

Human interleukin-2 anti-idiotypes.

We describe the generation of a monoclonal anti-idiotypic (anti-id) antibody directed against affinity purified rabbit antibodies (id) to recombinant human IL-2. This monoclonal antibody, 6A12, has the ability to inhibit the neutralization of IL-2 activity by the id, suggesting that it may bind at or near the IL-2 neutralizing site on the id. 6A12 exhibits IL-2 agonist activity on PHA-activated human T cells. The purified IgG of 6A12 is also shown to bind to a purified soluble recombinant p55 subunit of the IL-2 receptor. Furthermore, purified 6A12 shows inhibition of IL-2 activity in an IL-2 dependent mouse T cell line (CTLL) and this inhibition can be reversed by excess IL-2. These results suggest that although 6A12 may not be an exact 'internal image' of the receptor binding site of IL-2, it may bind to at least the P55 subunit of the ligand binding site on the high affinity IL-2 receptor complex.

Animals↗
PubMed1988

Toxicity of human recombinant interleukin-2 in the mouse is mediated by interleukin-activated lymphocytes. Separation of efficacy and toxicity by selective lymphocyte subset depletion.

Human recombinant interleukin-2 (rIL-2) was administered to normal and tumor-bearing BDF mice for 1 to 3 weeks, and the hematologic, clinical chemistry, gross and histopathologic findings were evaluated. Vascular leak syndrome (pulmonary edema, pleural effusion, ascites), hepatocyte necrosis, elevated hepatic serum transaminases, hypoalbuminemia, tissue and peripheral eosinophilia, thrombocytopenia, and prerenal azotemia were the detrimental effects of rIL-2 treatment. Vascular leak syndrome and hepatocyte necrosis were causally associated with vascular-oriented lymphocytic infiltration of pulmonary and hepatic parenchyma. Pleural effusions contained up to 99,000 cells/mm3, most of which were large granular lymphocytes. Antiserum to the glycolipid asialo GM1 (ganglio-n-tetrosylceramide), given simultaneously with rIL-2, prevented overt toxicity of rIL-2 (mortality, vascular leak syndrome, and hepatic damage) and substantially reduced infiltration of pulmonary and hepatic vasculature by asialo GM1+ lymphocytes. Asialo GM1 antiserum did not inhibit lymphoid hyperplasia, tissue infiltration by Lyt 2+ lymphocytes, tissue and peripheral eosinophilia, or thrombocytopenia in rIL-2 treated mice. Additionally, asialo GM1 antisera prevented toxicity, but not anti-tumor efficacy, of high dose rIL-2 therapy in BDF mice bearing the colon 38 adenocarcinoma. These results suggest that, in BDF mice and with this tumor model, vascular leak syndrome and hepatocyte necrosis are mediated by an endogenous subset of rIL-2-stimulated lymphocytes which are asialo GM positive, that mechanisms of toxicity and efficacy associated with high dose rIL-2 therapy are not necessarily the same, and that these mechanisms can be therapeutically separated.

Adenocarcinoma↗
PubMed1986

Synergy between recombinant interleukin 2 (rIL 2) and IL 2-depleted lymphokine-containing supernatants in facilitating allogeneic human cytolytic T lymphocyte responses in vitro.

Supernatants from human mixed leukocyte cultures or lectin-depleted supernatants from cultures of PHA-activated human peripheral blood leukocytes were depleted of IL 2 by passage over an anti-human rIL2 immunoadsorbent column. The column eluates were concentrated, dialyzed, and tested for their ability to synergize with human rIL 2 in facilitating human cytolytic T lymphocyte (CTL) responses to allogeneic, uv-irradiated HT144 melanoma cells in vitro. CTL were generated in the presence of 1 X 10(-4) M hydrocortisone sodium succinate in order to minimize the generation of nonspecific lymphokine-activated killer (LAK) cells. IL 2-depleted lymphokine-containing supernatant (LKS), alone or in the presence of less than or equal to U/ml rIL 2 did not stimulate significant CTL responses. Recombinant IL 2 at greater than 2 U/ml stimulated weak CTL responses in the absence of LKS. However, strong synergistic CTL responses were observed when both IL 2-depleted LKS and greater than 2 U/ml rIL 2 were added to the cultures. CTL generated in these cultures could be distinguished from nonspecific LAK cells on the basis of their i) specificity, ii) T3 phenotype, and iii) kinetics of generation. Nevertheless, rIL 2 and IL 2-depleted LKS were sometimes observed to synergize in facilitating the generation of nonspecific LAK cells as well as the generation of specific CTL. When the times at which rIL 2 and IL 2-depleted LKS were added to the cultures were varied, IL 2 was found to be required early in CTL responses, whereas the synergistic factor(s) in LKS seemed to act later. Recombinant human interferon-gamma was unable to replace LKS in synergizing with rIL 2 to elicit CTL responses. In summary, these experiments suggest that LKS contains a late-acting factor(s), antigenically distinct from IL 2, which synergizes with IL 2 in facilitating human CTL responses.

Biological Products↗
PubMed1986

Ultrastructural features of the lymphocyte-stimulated halos produced by human glioma-derived cells in vitro.

Many glioma-derived cell lines have the capability of escaping cell-mediated immune attack. One mechanism of escape is the secretion of a hyaluronidase-sensitive mucopolysaccharide coat by these cells. This coat prevents contact and tumor cell killing by specific cytolytic allogeneic lymphocytes. The production of the coat by the tumor cells is stimulated by a macromolecular factor released by peripheral blood mononuclear (PBMC) cells in culture. We have examined the morphologic and ultrastructural features of this extracellular matrix. Three coat-producing lines were studied. Under phase contrast light microscopy, the coat is a clear pericellular 'halo'. To stain this zone, ruthenium red and Alcian Blue 8 G stains, which bind to acid mucopolysaccharides (to a large extent, hyaluronic acid), were used. The two stains produced similar results. With light microscopy, a weblike pattern of stain was evident throughout the halo region. With transmission electron microscopy, staining was found along the plasma membrane of the glioma cells and their microvilli, stretching in long, branching filaments from these surfaces and, in some instances, from one microvillus to the next. Since mucopolysaccharide matrices have a large aqueous component, it was necessary to determine whether dehydration alters the stain pattern. Therefore, undehydrated ruthenium red stained specimens from each culture were embedded in Quetal 651 (Ted Pella, Inc., Tustin, CA), a water soluble plastic. No morphologic differences were noted between the hydrated and dehydrated specimens. This study indicates that numerous long microvilli and a secreted mucopolysaccharide matrix are important structural elements of the lymphocyte-stimulated tumor cell halo in vitro. The mechanism by which the PBMC factor stimulates coat formation and the importance of the coat in in vivo tumor defenses remain to be elucidated.

Brain Neoplasms↗
PubMed1985

p215 and p24: two membrane-associated proteins expressed on cloned cytolytic T-cells but not on cloned helper T-cells.

Cloned lines of murine alloreactive cytolytic and helper T cells were derived from secondary mixed leukocyte cultures. Cells from three TC lines and four TH lines were internally labeled with 35S-methionine and then disrupted by hypotonic lysis. Low density (plasma membrane-enriched) and high density (endoplasmic reticulum-enriched) membrane fractions were isolated from each cloned cell line and analyzed by SDS-PAGE under reducing conditions. Two proteins were identified which were associated with membrane fractions from each of the TC lines but none of the TH lines. One of these, p215, migrated as a broad band with an apparent molecular weight of 200-220 kD. The other, p24, migrated as a sharp band or closely spaced doublet with an apparent molecular weight of 24 kD. Immunoprecipitation studies using monoclonal antibodies to T200, LFA-1, Thy 1, and Lyt 2 revealed that p215 was a variant of T200 found on TC lines but not on TH lines. Treatment of solubilized membrane proteins from TH lines with anti-T200 precipitated a 180-195 kD protein band seen on each of the TH lines but none of the TC. In contrast, p24 was not precipitated by any of these monoclonal antibodies. It appears that p24 represents a previously unidentified protein which is unique to TC and thus deserving of further study as to its functional significance.

Animals↗
PubMed1985

Comparison of membrane-associated proteins of murine cytolytic and helper cloned T-cell lines: identification of a protein, p24, prominent in membrane fractions from cytolytic but not helper T-cells.

It has recently been reported that liposomes containing membrane components from cytolytic T-cell (TC) clones could transfer lytic activity to noncytolytic T- and B-cell lines, strongly suggesting that TC possess membrane-associated molecules which noncytolytic lymphocytes lack and which play a critical role in the lytic mechanism. It was thus of interest to compare the membrane-associated proteins from TC-lines to those of noncytolytic helper T-cell (TH) lines to determine whether any membrane-associated proteins unique to TC could be identified. Cells from three TC-lines and four TH-lines were internally labelled with [35S]methionine and then disrupted by hypotonic lysis. Low-density (plasma membrane enriched) and high-density (endoplasmic reticulum enriched) membrane fractions were isolated from each cloned cell line and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Two proteins were identified which were prominent in the membrane fractions from each of the three TC-lines but not in the membrane fractions from any of the four TH-lines. One of these, p215, migrated as a broad band with an apparent mol. wt of 215,000. The other, p24, migrated as a sharp band, or tightly spaced doublet, with an apparent mol. wt of 24,000. Immunoprecipitation studies using monoclonal antibodies to T200, LFA-1, Thy 1 and Lyt 2 suggested that p215 was a variant of T200 found on TC-lines but not on TH-lines. Treatment of solubilized membrane proteins from TH-lines with anti-T200 precipitated a 185-kD protein seen on each of the TH-lines but on none of the TC-lines. In contrast, p24 was not precipitated by any of these monoclonal antibodies. It therefore appears that p24 represents a previously unidentified protein which is strongly expressed by TC but not by TH and is thus deserving of further study as to its functional significance.

Animals↗
PubMed1984

Differential effects of positive and negative proliferative stimuli on murine cytolytic and helper T-cell clones.

Studies were performed to determine whether substances could be identified which exhibited differential regulatory effects--either positive or negative--on the growth of murine alloreactive cytolytic (Tc) and helper (Th) cloned T-cell lines. The following lines of evidence suggested that Tc and Th proliferate in response to the same growth factor (GF). (1) When GF-containing fluids from cultures of phorbol myristic acetate (PMA)-activated EL4 thymoma were fractionated by a variety of biochemical techniques. Tc and Th eluted together. (2) Absorption of GF-containing supernatants with either cloned Tc or cloned Th depleted GF activity for each to a similar extent, and GF eluted from either Tc or Th to which it had adsorbed supported the proliferation of Tc and Th equally well. (3) Lectin-depleted supernatants from cultures of concanavalin A (Con A)-activated Th stimulated the proliferation of Th as well as Tc. (4) Recombinant human interleukin (IL-2) supported the growth of Tc and Th with equal efficiency. On the other hand, the following observations indicated that Tc and Th differed in their responses to inhibitors of GF-driven proliferation. (1) Con A at greater than or equal to 0.3 micrograms/ml inhibited the GF-driven proliferation of each of three Th lines but not either of two Tc lines. To the contrary, Con A enhanced GF-dependent proliferation of Tc. (2) Like Con A, allogeneic splenocytes selectively depressed GF-driven proliferation of Th but not Tc. (3) A substance generated during the acid elution of GF from cells, possibly a modified fetal calf serum component, greatly reduced the GF-driven proliferation of Tc but not Th. These results suggest that differential control of the proliferation of Tc and Th in cellular immune responses may be achieved via negative regulatory signals and raise the possibility that substances which can selectively depress the proliferation of specific T-cell subsets might be found which would be of therapeutic value.

Animals↗
PubMed1984

Hydrocortisone suppresses the generation of nonspecific "anomalous" killers but not specific cytolytic T lymphocytes in human mixed lymphocyte-tumor cultures.

Interpretation of results with the use of effector populations generated in human mixed lymphocyte tumor cultures (MLTC) has in many cases been clouded by the presence of two distinct cytolytic effectors: specific cytolytic T lymphocytes (CTL) and nonspecific anomalous killers (AK). The addition of 5 to 50 X 10(-6) M hydrocortisone sodium succinate (HC) to "three-cell" allogeneic human MLTC containing responder lymphocytes, irradiated allogeneic glioma cells, and irradiated third-party stimulator lymphocytes consistently reduced the generation of AK by greater than 90% while having little or no effect on the generation of CTL specific for antigens present on the glioma cells. HC was similarly effective in blocking the generation of AK when added to cultures of responder cells incubated with lymphokine-containing supernatants from mixed lymphocyte cultures. Kinetic experiments indicated that HC both decreased the initial rate of appearance of AK activity and subsequently caused the AK response to decline more rapidly. HC had only a small inhibitory effect on the lytic action of AK generated in its absence. The ability of HC to suppress strongly the generation of nonspecific but not specific cytolytic effectors suggests that nonspecific AK are not polyclonally activated CTL or CTL at an early stage of differentiation, but rather represent a distinct cytolytic effector system. The inclusion of HC in human MLTC may provide a useful tool for distinguishing between lysis due to the generation of specific CTL and lysis due to the generation of nonspecific AK.

Antibodies, Monoclonal↗
PubMed1984

In vitro studies on the cell-mediated immune response to human brain tumors. II. Leukocyte-induced coats of glycosaminoglycan increase the resistance of glioma cells to cellular immune attack.

We have examined the ability of cultured human glioma cells to elicit allogeneic cytolytic lymphocyte responses in vitro in order to delineate properties of glioma cells that may contribute to their ability to escape cellular immune attack. When glioma cells were cultured together with allogeneic peripheral blood mononuclear cells (PBMC) in mixed lymphocyte-tumor cultures (MLTC), it was observed that cells from eight of 12 glioma lines were surrounded by clear pericellular "halos," which appeared to impede contact between PBMC and the glioma cells. Enzymatic, histochemical, and immunochemical studies indicated that these halos represented glycosaminoglycan (GAG) coats that contained hyaluronic acid (HA) as a major constituent. Electron microscopic studies demonstrated the presence of many thin microvillous processes spanning the width of the halos. The presence of GAG coats around glioma cells in MLTC reduced the generation of cytolytic T lymphocytes specific for antigens on the glioma cells. Likewise, these cell coats decreased the lysis of glioma cells by cytolytic lymphocytes, once generated. The production of thick coats of GAG by glioma cells was induced by interaction of glioma cells with a nondialyzable factor produced by PBMC in culture. This factor did not cause glioma cells to release increased amounts of HA into the medium, but rather increased the production of HA that remained associated with the glioma cell surface. The formation of thick, protective GAG coats by glioma cells as a result of their interaction with the PBMC-derived factor constitutes a nonspecific suppressor mechanism that may contribute to the ability of this class of human solid tumors to evade cellular immune attack.

Brain Neoplasms↗
PubMed1983

Lymphoid cell-glioma cell interaction enhances cell coat production by human gliomas: novel suppressor mechanism.

Certain human glioma lines produce mucopolysaccharide coats that impair the generation of cytolytic lymphocytes in response to these lines in vitro. Coat production is substantially enhanced by the interaction of glioma cells with a macromolecular factor released by human peripheral blood mononuclear cells in culture. This interaction thus constitutes an unusual mechanism by which inflammatory cells may nonspecifically suppress the cellular immune response to at least one class of solid tumors in humans.

Animals↗
PubMed1982

Mechanisms by which human gliomas may escape cellular immune attack.

Whereas substantial evidence indicates that the majority of glioma patients make humoral immune responses to their own tumours, the evidence that glioma patients make significant cellular immune responses is more tenuous and controversial. In order to study those properties of human gliomas that might contribute to their ability to escape cell-mediated immune attack, we have examined the ability of cultured human glioma cells to elicit allogeneic cytolytic lymphocyte responses in vitro. Five of ten glioma lines were unable to elicit allogeneic cytolytic lymphocyte responses in mixed lymphocyte-tumour cultures, despite the presence of serologically detectable alloantigens on the surface of the glioma cells. Analysis of the reasons why certain glioma lines failed to stimulate cytolytic lymphocyte responses revealed three distinct mechanisms by which human gliomas may escape cellular immune attack: 1. a defect in immunogenicity which can be overcome by "help" from an allogeneic mixed lymphocyte reaction, 2. the secretion of a protective mucopolysaccharide coat, and 3. the production of macromolecular immunosuppressive substance(s). The implications of these findings for the immunotherapy of human gliomas are discussed.

Adult↗
PubMed1982

In vitro studies on the cell-mediated immune response to human brain tumors. I. Requirement for third-party stimulator lymphocytes in the induction of cell-mediated cytotoxic responses to allogeneic cultured gliomas.

For study of those properties of human gliomas that might contribute to their ability to escape cell-mediated immune attack, cultured human glioma cells were examined for their ability to elicit allogeneic cytolytic lymphocyte responses in vitro. Of 9 glioma lines, 5 were unable to elicit allogeneic cytolytic lymphocyte responses in mixed lymphocyte--tumor cultures although the concentration of stimulating glioma cells was varied over a fortyfold range. However, lymphocytes specifically cytolytic for 4 of the nonstimulatory lines could be generated if irradiated, third-party stimulator lymphocytes were added to cultures containing responder lymphocytes and glioma cells. The specific cytolytic lymphocytes produced in these cultures were inactivated by treatment with the monoclonal anti-T-cell antibody OKT3 plus complement and were thus identified as T-cells. However, nonspecific, non-T-lytic effectors were also generated. The results of these experiments demonstrated that certain cultured gliomas possessed a defect in immunogenicity that can be overcome by "help" from an allogeneic mixed lymphocyte reaction. The possible nature of this help and the potential implications of these results for the immunotherapy of human gliomas are discussed.

Astrocytoma↗
PubMed1981

T11: a new protein marker on activated murine T lymphocytes.

Murine lymphocytes were activated in vitro in mixed lymphocyte cultures (MLC) or by the addition of the mitogens concanavalin A (Con A), phytohemagglutinin (PHA), or E. coli lipopolysaccharide (LPS). Activated lymphocytes were internally labeled with 35S-methionine and then disrupted by hypotonic lysis. A plasma membrane-enriched fraction was isolated from each cell population, and the 35S-labeled proteins in this fraction were examined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). An intensely labeled band, the position of which indicated an apparent m.w. of 11,000, was observed when plasma membrane-enriched fractions from MLC- and Con A-activated cells were subjected to SDS-PAGE. In contrast, plasma membrane-enriched fractions from normal spleen cells, LPS-activated cells, PHA-activated cells, and EL4, RDM4, and P815 tumor cells possessed little or none of this protein, which we have designated T11. T11 was not found in the soluble cytoplasmic protein from MLC-activated cells. Hence the presence of T11 in the plasma membrane-enriched fraction from these cells cannot be attributed to contamination by cytoplasmic protein. Removal of T cells from populations of MLC-activated cells by treatment with monoclonal anti-Thy 1 and complement removed T11. These results suggest that T11 may represent a new protein marker on a subclass of activated T lymphocytes.

Animals↗