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Biomedical subjects

L P Svedersky

Publications and source records attributed to L P Svedersky.

13 recordsLinked to original sources
PubMed1987

Safety issues related to the use of recombinant DNA-derived cell culture products. I. Cellular components.

Anti-thymocyte serum (ATS) treated newborn rats were used to assess the tumorigenic potential of mammalian cell and mammalian cell culture derived substances. Injection of as much as 100 micrograms of Chinese hamster ovary (CHO) DNA, an amount in excess of 10(8) fold more than might be present in one dose of a typical final product derived from mammalian cell cultures, failed to initiate a tumor in immunosuppressed animals. In addition, injection of 10 micrograms of activated oncogene cloned from a human bladder carcinoma was also insufficient to initiate a tumor in immunosuppressed animals. Injection of some but not all CHO cell lines did result in tumor growth which upon isoenzyme analysis was verified to be of hamster origin. Of importance was the finding that recombinant tissue plasminogen activator (rt-PA) and hepatitis B surface antigen (HBsAg) vaccine failed to induce tumors in either normal or immunosuppressed rats. The results suggest that the presence of minute quantities of CHO derived nucleic acid fragments in these final products have no discernable tumorigenic potential.

Animals↗
PubMed1986

Natural killer-sensitive targets stimulate production of TNF-alpha but not TNF-beta (lymphotoxin) by highly purified human peripheral blood large granular lymphocytes.

Highly purified populations of large granular lymphocytes (LGL) have been shown to mediate natural killer (NK) cell activity. The mechanism of target cell killing by NK cells is as yet undefined; however, it has been postulated that such killing may involve soluble cytotoxic factors produced and secreted by NK cells. The data presented show that NK-sensitive, but not NK-resistant, tumor cell lines induce highly purified populations of human LGL to produce factors with cytotoxic and/or cytostatic activities. We have identified one of these factors as tumor necrosis factor-alpha (TNF-alpha), and have shown that production of this factor is enhanced by recombinant human interferon-gamma (rHuIFN-gamma). We have also examined the role of TNF-alpha in the cytotoxic function of NK cells. The data show that although highly purified LGL populations produce low levels of TNF-alpha, the cytotoxic/cytostatic activity of this lymphokine on tumor target cells does not correlate with the cytotoxic activity of highly purified populations of LGL on tumor target cells. Furthermore, NK cell-mediated cytotoxicity is not reliably inhibited by antibodies directed against various epitopes of recombinant human TNF-alpha and/or recombinant TNF-beta (lymphotoxin) or rHuIFN-gamma. These data show that although TNF-alpha is produced by highly purified NK-containing LGL cell populations, this factor does not appear to be responsible for NK cell cytotoxicity against classical NK target cells such as Molt-4 or K562. We suggest that NK function can be attributed to a combination of factors rather than to a single factor alone, and that at least two major phenomena are involved in LGL function: the rapid cytotoxic events which lead to the cell lysis measured in classical in vitro NK assays such as against K562; and the release of factors such as TNF-alpha with cytotoxic/cytostatic activities which would inhibit the growth of invading tumor cells in vivo.

Animals↗
PubMed1985

In vivo augmentation of natural killer activity by combined treatment with recombinant gamma interferon and interleukin-2.

The in vivo regulation of natural killer (NK) cell function by recombinant murine gamma interferon (rMuIFN-gamma) and recombinant human interleukin-2 (rHuIL-2) was investigated. Peritoneal exudate-derived natural killer (PE-NK) cells of mice treated with rMuIFN-gamma or rHuIL-2 exhibited significantly enhanced cytolytic activities against YAC-1 target cells. Compared with animals receiving treatment with either rMuIFN-gamma or rHuIL-2 alone, the sequential treatment of mice with both agents resulted in a significantly greater enhancement of PE-NK cell function, especially when rMuIFN-gamma was administered 24 h before treatment with rHuIL-2. The cytolytic activities were significantly diminished after pretreatment of effector cells with anti-Qa-5 antiserum and complement but not with anti-Lyt-3.2 antiserum. These data constitute the first evidence demonstrating the association between IFN-gamma and IL-2 in the regulation of NK cell function in vivo, reinforce the potential benefit of combined treatment with biological response modifiers, and show that the schedule of administration may be a critical requirement for optimal benefits of combined lymphokine treatment in vivo.

Animals↗
PubMed1985

Interferon-gamma enhances induction of lymphotoxin in recombinant interleukin 2-stimulated peripheral blood mononuclear cells.

Human peripheral blood mononuclear cells (PBMC) were induced by recombinant human interleukin 2 (rIL 2) to secrete lymphotoxin (LT) and interferon-gamma (IFN-gamma). Induction of both LT and IFN-gamma by rIL 2 is regulated at the transcriptional level. Treatment of PBMC with rIL 2 in combination with recombinant human IFN-gamma (rIFN-gamma) resulted in an earlier appearance of LT mRNA and an augmented production of LT than did rIL 2 treatment alone. IFN-gamma alone had no effect on production of either LT or its mRNA. PBMC cultured in the presence of rIL 2 plus anti-rIFN-gamma resulted in decreased LT production. Only a 15-min incubation of PBMC with rIL 2 is needed to stimulate LT production, whereas 3 hr is necessary for IFN-gamma production. These results suggest that rIL 2, in addition to being a T cell growth factor, may exhibit other activities through induction of LT and IFN-gamma.

Animals↗
PubMed1985

Activation of human polymorphonuclear neutrophil functions by interferon-gamma and tumor necrosis factors.

Recombinant human interferon-gamma (rHuIFN-gamma) and natural human tumor necrosis factor beta (nHuTNF-beta) (previously called lymphotoxin), purified to homogeneity, were used to assess their effects on certain functions of human polymorphonuclear neutrophils (PMN) in vitro. The treatment of PMN with 100 U of either rHuIFN-gamma or nHuTNF-beta for 20 min significantly increased their ability to phagocytize 1.5-microns latex beads as detected by flow cytometry. Preparations of recombinant human TNF-beta (rHuTNF-beta) showed activities similar to those of its natural counterpart in activating phagocytosis. In addition, a significant enhancement in PMN-mediated antibody-dependent cellular cytotoxicity was observed after treatment for 2 hr with IFN gamma and both TNF-alpha and TNF-beta. The enhancement by treatment with a combination of rHuIFN-gamma and nHuTNF-beta exceeded the enhancement caused by either agent alone. We also show that although lipopolysaccharide (LPS) is a potent stimulator of PMN function, polymyxin B can block LPS-induced but not lymphokine-induced activation. These data demonstrate new activities for both TNF-alpha and TNF-beta in augmenting the phagocytic and cytotoxic activities of PMN.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1985

Effect of interleukin 2, interferon-gamma, and mitogens on the production of tumor necrosis factors alpha and beta.

Human peripheral blood mononuclear cells (PBMC) were induced by recombinant interleukin 2 and mitogens to secrete two distinct cytotoxic polypeptides, tumor necrosis factor-alpha (TNF-alpha) and tumor necrosis factor-beta (TNF-beta), previously called lymphotoxin. Treatment of PBMC with recombinant human interleukin 2 (rIL 2) or mitogens in combination with recombinant human interferon-gamma (rIFN-gamma) resulted in augmented production of both TNF-alpha and TNF-beta. rIFN-gamma alone had no effect on production of either cytotoxic polypeptide. TNF-alpha was produced within 2 to 3 hr after induction and was the major cytotoxin produced by PBMC during the first 48 hr of culture, after which time TNF-beta became the predominant species. TNF-beta was first secreted into the media after 8 hr of induction. Enhanced levels of both TNF-alpha and TNF-beta were seen when the PBMC were separated into adherent and nonadherent cells. Both TNF-alpha and TNF-beta were induced in different tumor cell lines of hematopoietic origin. The results demonstrate that the production of TNF-alpha and TNF-beta can be enhanced by two lymphokines, IL 2 and IFN-gamma.

Animals↗
PubMed1985

Interferon gamma: more than a MAF.

The precise immunoregulatory activities of particular lymphokines have been difficult to define due to the presence of contaminating molecules in the purified natural preparations under study. Thus, the application of recombinant DNA technologies to lymphokine research has been instrumental in elucidating the biologic properties of many of these factors. In particular, with the availability of recombinant gamma interferon (rIFN-gamma) a variety of immuno-regulatory functions, including natural killer activation, enhancement of lymphokine production, macrophage activation, and cell surface Ia expression, have been clearly shown to be mediated by this lymphokine. Recently we have compared the properties of macrophage activating factor (MAF) to those of natural and rIFN-gamma. This article reviews our evidence suggesting that IFN-gamma is a major MAF. In addition, we present evidence for another activity of IFN-gamma, namely, its ability to regulate the growth of certain interleukin 2 (IL-2)-dependent cytotoxic T cell lines.

Animals↗
PubMed1984

Biological and antigenic similarities of murine interferon-gamma and macrophage-activating factor.

Murine peritoneal exudate cells (PEC) treated with murine recombinant interferon-gamma (IFN-gamma) (greater than 99% estimated purity), or concanavalin A-stimulated spleen cell supernatants developed tumoricidal properties (macrophage activation factor [MAF] activity). MAF activity was found to occur with treatments of 10 U/ml IFN-gamma, and at levels as low as 1 U/ml IFN-gamma if a second signal (5 ng/ml endotoxin) was present in the MAF assay. Endotoxin (lipopolysaccharide [LPS]) alone at these levels failed to induce MAF; induction of MAF was observed at 1,000-fold greater levels. The ability of IFN-gamma to stimulate murine PEC was species specific. Various sources of materials that displayed MAF activity, including supernatants from interleukin 2-dependent cloned cytotoxic murine T lymphocyte lines that did not display detectable antiviral activity, were neutralized by antibody raised and affinity purified against recombinant IFN-gamma. Thus, IFN-gamma, although never detectable by antiviral assays, appears to be present in many lymphokine preparations and has potent macrophage activation capability.

Animals↗
PubMed1984

Augmentation of human natural cell-mediated cytotoxicity by recombinant human interleukin 2.

Human peripheral blood mononuclear cells (PBMC) demonstrated increased natural cell-mediated cytotoxicity (NCMC) activity after only 5 min of exposure to purified recombinant human IL 2 or interferon (IFN)-gamma. The mechanism of NCMC augmentation by treatment with IL 2 is not entirely dependent on IFN-gamma production because: a) IL 2 was found to augment NCMC activity at levels which did not induce detectable IFN-gamma; b) IL 2 required only 5 min of exposure to PBMC to augment NCMC activity, whereas 3 hr of contact were required to demonstrate detectable IFN-gamma levels; c) the levels of NCMC enhancement by treatment with IL 2 exceeded the amount of NCMC enhancement that could be due to IFN alone; d) anti-recombinant IFN-gamma, which totally eliminated the augmentation of NCMC enhancement by IFN-gamma, only partially reduced the augmentation of NCMC activity by IL 2; and e) combination treatment of PBMC with IL 2 and IFN-gamma resulted in a synergistic enhancement of NCMC. The results strongly support the conclusion that augmentation of NCMC by IL 2 and IFN-gamma involve overlapping mechanisms.

Cytotoxicity, Immunologic↗
PubMed1982

Induction and augmentation of mitogen-induced immune interferon production in human peripheral blood lymphocytes by N alpha-desacetylthymosin alpha 1.

Treatment of human peripheral blood lymphocytes with cloned N alpha-desacetylthymosin alpha 1 induced interferon production. The kinetics is similar to that of mitogen-induced interferon induction. N alpha-desacetylthymosin alpha 1, in combination with mitogen, augments the amount of interferon produced. This interferon is immune interferon (IFN-gamma) as determined by sensitivity to pH 2, lack of neutralization by antibodies to IFN-alpha or IFN-beta and absence of activity of MDBK cells. Although the mechanism of induction of IFN-gamma by N alpha-desacetylthymosin alpha 1 is unclear, this compound is not mitogenic at concentrations causing IFN-gamma production. These results indicate that thymic factors may also participate in the regulation of IFN-gamma-production.

Cells, Cultured↗
PubMed1979

Immune suppression by cultured lymphocyte supernates of tumor-bearing hosts.

A nonspecific immunosuppressive factor produced by lymphocytes of tumor-bearing hosts has been demonstrated. A modified Jerne plaque was used to quantify IgM antibody production of sheep erythrocyte-immune Swiss mouse lymphocytes (IL). Significant suppression of IgM antibody production was found when IL were treated with cultured lymphocyte supernates of 4198 fibrosarcoma-bearing mice. The suppressive activity was found to be significant six days prior to any visible tumor development, and, through the use of glass and nylon wool columns, appears to be produced by T cells. Similar immunosuppressive activity was found in 22 cancer patients tested as above, compared either to 16 patients who previously had had solid tumors but are now without clinical disease or to 19 normal controls.

Aged↗