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E F Wheelock

Publications and source records attributed to E F Wheelock.

At least 19 recordsLinked to original sources
PubMed1994

Characterization and purification of a macrophage-triggering factor produced in Mycoplasma arginini-infected L5178Y cell cultures.

The supernatant of Mycoplasma arginini-infected murine L5178Y T lymphoma cell cultures (SN-L51) synergizes with small concentrations of IFN-gamma to activate murine peritoneal, thioglycollate-elicited macrophages (M phi) to exhibit cytostatic activity against tumor cells. Treatment of M phi with IFN-gamma and SN-L51 sequentially, but not in the reverse order, activates M phi, which indicates that SN-L51 contains a M phi-triggering factor (MTF). MTF activity could be inhibited by small concentrations of prostaglandin E2, but not by polymyxin B. M phi activated by IFN-gamma plus MTF produce cytostatic effects on tumor cells through a nitric oxide-dependent pathway. MTF activity in SN-L51 is associated with infection of L5178Y cells by M. arginini. Mycoplasma-free L5178Y cells do not produce MTF activity, infection of these L5178Y cells with M. arginini generates the activity, and supernatants of pure M. arginini cultures contain MTF activity. MTF activity is thermostable and resistant to acid, dilute alkali, proteases, and nucleases. MTF was partially purified by ammonium sulfate precipitation, chromatography, electrophoresis, and electroelution. On 12.5% SDS-urea gels, MTF activity migrated with a molecular mass of 2.5 to 4 kDa. MTF activity and the silver staining of this band was resistant to proteinase K; however, Coomassie staining of this band was abolished by proteinase K. The combined data suggest that MTF is either a stable peptide or a peptide linked to lipid or carbohydrate.

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PubMed1990

Maintenance and cure of the L5178Y murine tumor-dormant state by interleukin 2: dependence of interleukin 2 on induced interferon-gamma and on tumor necrosis factor for its antitumor effects.

We reported previously that treatment of peritoneal cell (PC) cultures prepared from mice which harbor L5178Y lymphoma cells in a tumor-dormant state in their peritoneal cavity with interleukin 2 (HuIL-2) stimulated antitumor cytotoxic activity in both the nonadherent and adherent populations derived from such cultures. We report here that HuIL-2 induced the production of murine gamma interferon (MuIFN-gamma) in these PC cultures and required Lyt-1-, Lyt-2-, and L3T4-expressing lymphocytes to do so. HuIL-2 required and synergized with this induced MuIFN-gamma to stimulate cytotoxic activity in the nonadherent PC and the MuIFN-gamma itself stimulated cytotoxic activity in the adherent PC. Cyclosporin A prevented both the induction of MuIFN-gamma and the development of antitumor cytotoxic activity in HuIL-2-treated PC cultures. An addback of exogenous MuIFN-gamma to HuIL-2-cyclosporin A-treated PC cultures and to the nonadherent subpopulation of such cultures, at a concentration which itself produced no antitumor effect, permitted HuIL-2 to induce its antitumor effect. We previously reported that MuIFN-gamma requires the action of murine tumor necrosis factor (MuTNF) to induce cytotoxic activity in PC cultures from tumor-dormant mice. We report here that HuIL-2 also requires the action of (MuTNF) to stimulate antitumor cytotoxic activity in PC cultures from tumor-dormant mice. These results indicate that HuIL-2 induces MuIFN-gamma and requires and synergizes with this MuIFN-gamma and with (MuTNF) to stimulate antitumor cytotoxic activity in PC cultures from tumor-dormant mice.

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PubMed1990

Maintenance and cure of the L5178Y murine tumor-dormant state by interleukin 2: in vivo and in vitro effects.

We studied the antitumor effects of recombinant human interleukin 2 (HuIL-2) in DBA/2 mice which harbor L5178Y lymphoma cells in a tumor-dormant state in the peritoneal cavity and in peritoneal cell (PC) cultures prepared from such mice. Intraperitoneal injection of 10,000 to 100,000 units of HuIL-2/day for 10 days eliminated tumor cells from 30-45% of the mice, whereas no mice became tumor-free in the phosphate-buffered saline-treated control group. In vitro, as little as 10 units/well HuIL-2 failed to stimulate cytotoxic activity in PC from normal mice. HuIL-2 directly stimulated antitumor cytotoxic activity in nonadherent but not in adherent PC cultures from tumor-dormant mice; however, treatment of whole PC from tumor-dormant mice with HuIL-2 resulted in the development of antitumor cytotoxic activity in the adherent PC population which were derived from such cultures. This suggests that the HuIL-2-treated nonadherent PC contributed to the cytotoxic activation of the adherent PC. Flow cytometric analysis of the PC from tumor-dormant mice revealed a polyclonal expansion of T-lymphocytes. Lyt-1+, Lyt-2+, and L3T4+ lymphocytes were all required for HuIL-2 to induce antitumor cytotoxic activity.

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PubMed1989

Immune regulation of the L5178Y murine tumor-dormant state: induction of cell- and soluble factor-mediated inhibition of tumor cell growth by tumor necrosis factor and gamma-interferon.

Small concentrations of recombinant murine tumor necrosis factor (rMuTNF) synergized with recombinant murine gamma-interferon (rMuIFN-gamma) to inhibit tumor cell growth in peritoneal cell (PC) cultures from tumor-dormant mice. A soluble inhibitor of tumor cell growth was produced in the rMuTNF-treated PC cultures, but there was no synergistic enhancement of production of this inhibitor by the addition of rMuIFN-gamma. Treatment of both plastic-adherent PC and nonadherent PC cultures which contained L5178Y cells with rMuTNF + rMuIFN-gamma resulted in inhibition of tumor cell growth. However, in the absence of L5178Y cells, rMuTNF + rMuIFN-gamma induced antitumor cytotoxic activity in the plastic-adherent but not in the plastic nonadherent PC. These results indicate that the antitumor activity of rMuTNF + rMuIFN-gamma in PC from tumor-dormant mice involves both cell- and soluble factor-mediated mechanisms.

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PubMed1987

Interferon-gamma synergizes with tumor necrosis factor and with interleukin 1 and requires the presence of both monokines to induce antitumor cytotoxic activity in macrophages.

Small concentrations of recombinant murine interferon-gamma (MuIFN-gamma), recombinant human interleukin 1 (HuIL-1), and recombinant murine tumor necrosis factor (MuTNF), added separately to cultures of thioglycolate-elicited peritoneal macrophages, produced no cytotoxic activity against L5178Y cells, a tumor cell line which is resistant to the direct toxic effects of these cytokines, either alone or in combination. However, small concentrations of MuIFN-gamma when combined with small concentrations of either HuIL-1 or MuTNF activated these macrophages to produce cytotoxic effects against L5178Y cells; small concentrations of HuIL-1 and MuTNF in combination had no macrophage activating activity. Specific antibody to MuTNF blocked the macrophage-activating synergistic effects of MuIFN-gamma + HuIL-1, and specific antibody to HuIL-1 blocked the macrophage-activating activity of MuIFN-gamma + MuTNF, indicating that MuTNF was induced in macrophage cultures treated with MuIFN-gamma + HuIL-1, and that murine IL-1 was induced in macrophage cultures treated with MuIFN-gamma + MuTNF. These results indicate that all three cytokines are required for induction of antitumor cytotoxic activation of macrophages. Experiments with a concentration of MuIFN-gamma which alone could activate macrophages revealed that both MuTNF and murine IL-1 were required for this activation. The demonstration that small concentrations of these three cytokines can act synergistically, but not separately, to activate macrophages indicates the importance of cytokine combinations in immunoregulation and in anti-tumor cell-mediated immune responses.

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PubMed1987

Immune regulation of the L5178Y murine tumor-dormant state. II. Interferon-gamma requires tumor necrosis factor to restrain tumor cell growth in peritoneal cell cultures from tumor-dormant mice.

L5178Y lymphoma cells are restrained from progressive growth in peritoneal cell ("in vitro tumor-regressor" PC) cultures prepared from many DBA/2 mice which harbor the tumor cells in the peritoneal cavity in a tumor-dormant state. Treatment of these PC cultures with 'antibodies to murine interferon-gamma (MuIFN-gamma) and murine tumor necrosis factor (MuTNF) but not with antibody to interleukin 2 (IL-2) receptors eliminated the restraint on tumor cell growth and permitted their progressive proliferation. L5178Y cells were found to be resistant to the direct toxic effects of large concentrations (3,000 U/ml) of MuIFN-gamma and of MuTNF, either alone or in combination. Treatment of PC cultures from tumor-dormant mice, in which tumor cells grew progressively ("in vitro tumor-progressor"), but not PC cultures from normal mice, with exogenous MuIFN-gamma resulted in a marked inhibition of tumor cell growth. The MuIFN-gamma-induced cytotoxic activity was cell-mediated since no soluble tumor-cytotoxic factors could be detected in the cultures. MuIFN-gamma induced cytotoxic activity in plastic-adherent peritoneal cell (AD-PC) cultures, but induced no cytotoxic activity in nonadherent-PC cultures unless small numbers (2%) of AD-PC were present, and inclusion of antibody to MuTNF in these mixed PC cultures blocked the development of cytotoxic activity. Antibody to MuTNF also blocked the development of cytotoxic activity in cultures of MuIFN-gamma-treated whole PC and AD-PC from tumor-dormant mice. These results indicate that MuIFN-gamma and MuTNF are both important in restraining tumor cell growth in PC cultures from tumor-dormant mice, and that MuIFN-gamma requires the presence of MuTNF to induce cytotoxic activity in these cultures.

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PubMed1986

Immune regulation of the L5178Y murine tumor-dormant state. I. In vivo and in vitro effects of prostaglandin E2 and indomethacin on tumor cell growth.

Immunization and intraperitoneal challenge of DBA/2 mice with L5178Y lymphoma cells results in the suppression and maintenance of the L5178Y cells in a tumor-dormant state in the peritoneal cavity for many months. Cell-mediated immune responses involving lymphocytes and macrophages are involved in maintenance of the tumor-dormant state. Macrophages that have increased immunosuppressive activity and that produce increased amounts of PGE2 appear in the peritoneal cavity of tumor-dormant mice before the breakdown of the tumor-dormant state and formation of ascitic tumors. We report here that the tumor-dormant state can be terminated with formation of ascitic tumors by treatment of tumor-dormant mice with PGE2. Treatment with indomethacin results in inhibition of tumor cell growth and elimination of all recoverable tumor cells. Cultures of peritoneal cells (PC) from mice harboring L5178Y cells in a tumor-dormant state were used to analyze the PGE2 and indomethacin effects. Tumor cells did not grow out in the high-cell density PC cultures prepared from many tumor-dormant mice, but addition of PGE2 to these cultures resulted in tumor cell growth. The tumor cell growth that did occur in the PC cultures from some tumor-dormant mice was associated with PGE2 production by the associated host cells, and the addition of indomethacin to these cultures inhibited both PGE2 synthesis and tumor cell growth. Removal of plastic-adherent cells from the PC cultures eliminated the restraint on tumor cell growth. These experiments suggest that L5178Y tumor cells are maintained in a tumor-dormant state by host peritoneal cells, which are under PGE2 regulation.

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PubMed1986

Rapidly reversible resistance to immune lysis of L5178Y lymphoma cells in a tumor-dormant state in DBA/2 mice.

L5178Y cells in a tumor-dormant state in DBA/2 mice escape lysis by cytolytic T-lymphocytes and activated macrophages. In the present report these tumor cells were found to be less susceptible to lysis by anti-H-2, anti-Thy 1.2, and anti-AKR antibodies plus complement than was the same tumor cell population removed from tumor-dormant mice and allowed to proliferate in a nonimmune environment in vivo or in vitro. This rapidly reversible resistance to immune lysis may be due to arrest of the tumor cells in the cell cycle during the tumor-dormant state.

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PubMed1986

A radiosensitive T-lymphocyte associated with resistance of DBA/2 mice harboring Friend leukemia virus-dormant infections to transplantable Friend leukemia virus-erythroleukemia cells.

The immunobiology of Friend erythroleukemia virus (FLV) has been the focal point of much research into immunological control of leukemia. We have been studying a murine model in which a rapidly fatal FLV infection of DBA/2 mice is suppressed to a dormant state by treatment with statolon, a double stranded RNA extract of Mycoplasma stoloniferum. We report here that mice with FLV-dormant infections resist the accumulation of transplanted FLV-transformed erythroleukemia cells (FLC-745) and that FLC-745 cells persist in the spleen for a prolonged period. Winn assays revealed that the spleen of FLV-dormant mice contain radiosensitive T-lymphocytes with anti-FLC-745 cell activity. Whole body irradiation of FLV-dormant mice abrogated their resistance to transplanted FLC-745 cells and confirmed the radiosensitivity of the protective immune response.

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PubMed1984

Phenotypic shifts in the L5178Y lymphoma population during progression of the tumor-dormant state in DBA/2 mice.

We evaluated the phenotypic changes that take place in the L5178Y tumor cell population during the establishment, maintenance, and termination of the L5178Y tumor-dormant state in DBA/2 mice. Since there is considerable variation among DBA/2 mice in the course of the L5178Y tumor-dormant state, analysis of these phenotypic changes required prospective studies on individual mice. Therefore, we developed a partial peritoneal lavage technique which could be performed repeatedly on an individual mouse without killing the mouse and without terminating the tumor-dormant state. The partial peritoneal lavage technique provided cell samples that were quantitatively representative of the entire peritoneal cell contents without altering the relative proportions or total number of host peritoneal cell subpopulations. Tumor cell clones were isolated from the uncloned L5178Y cell inoculum that was used to initiate the tumor-dormant state, and from the partial peritoneal lavage performed on individual mice at regular intervals throughout the tumor-dormant state until each mouse developed an ascitic tumor. We found that the uncloned L5178Y cell population is heterogeneous, with the majority of the cells [approximately 80% of the clonal populations ("original" phenotype)] able to compete as well as the uncloned L5178Y cell population for immune cytolytic T-lymphocyte activity, and a smaller percentage [approximately 20% of the clones ("emergent" phenotype)] competing significantly less but similar to the tumor cell population which grows out as an ascitic tumor at the termination of the tumor-dormant state. However, both "original" and "emergent" phenotypes encompass a range of subpopulations which have the respective characteristics. There was a progressive enrichment in the tumor cell population for "emergent"-phenotype cells as mice progressed through the tumor-dormant state. In the 30-day period prior to tumor emergence, only "emergent"-phenotype cell clones were isolated. These data indicate that, during the course of the tumor-dormant state, there is continual selection by immune cytolytic T-lymphocytes for "emergent"-phenotype cells, which preexist in the L5178Y cell population used to initiate the tumor-dormant state, and that the progressive enrichment of "emergent"-phenotype cells in the peritoneal cavity is associated with and may be responsible for termination of the tumor-dormant state.

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PubMed1984

Characterization of L5178Y cell phenotypes isolated during progression of the tumor-dormant state in DBA2 mice.

During the course of the L5178Y tumor-dormant state in DBA/2 mice, there is continual selection of a tumor cell subpopulation ("emergent" phenotype) from the uncloned original L5178Y population used to initiate the tumor-dormant state. In vivo and in vitro experiments show that the emergent-phenotype tumor cells are less capable than "original"-phenotype cells, which constitute the majority of the L5178Y cell inoculum, of restimulating cytolytic T-lymphocyte (CTL) activity in tumor-dormant mice and are less susceptible to lysis by those CTL. Both original- and emergent-phenotype tumor cells are capable of eliciting an immune CTL response in naive mice, but again emergent-phenotype cells are poorly lysed by this response. As a consequence of these characteristics, emergent-phenotype cells rapidly form ascitic tumors when used as a challenge in L5178Y cell-immunized mice and cannot establish a tumor-dormant state. Results presented here and in previous publications indicate that CTLs are the major host cells involved in the selection of emergent-phenotype L5178Y cells during the course of the tumor-dormant state. Heterogeneity of the tumor cell challenge inoculum is important in establishing the L5178Y tumor-dormant state. The state, once established, is maintained by an immune CTL response which is continuously being restimulated by the strongly immunogenic original-phenotype L5178Y cells. The tumor-dormant state terminates when the less immunogenic and more immunoresistant emergent-phenotype tumor cells predominate and escape the waning immune response.

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PubMed1983

Cytotoxic T lymphocytes in DBA/2 mice harboring L5178Y cells in a tumor-dormant state.

Previous experiments have demonstrated a temporal relationship between the decline of cytotoxic T lymphocyte (CTL) activity in the peritoneal cavity of DBA/2 mice harboring L5178Y cells in a tumor-dormant state and the appearance of ascitic tumors. Some tumor-dormant mice remain clinically normal for many weeks after the decline of CTL activity, and this activity can be rapidly restimulated by an IP inoculation of irradiated L5178Y cells. We report here that the peritoneal cells from many tumor-dormant mice can be stimulated to cytolytic activity in vitro when cultured for 4 days either with or without the addition of irradiated L5178Y cells. Peritoneal cell populations which cannot be stimulated in vitro can suppress the generation of CTL in those populations which can be stimulated. The tumor-dormant state may terminate when suppressor cells in the peritoneal cavity of tumor-dormant mice inhibit the generation of CTL activity and permit tumor cells to produce an ascitic tumor.

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PubMed1983

Enhanced suppressor macrophage activity associated with termination of the L5178Y cell tumor-dormant state in DBA/2 mice.

Both cytolytic T-lymphocytes and cytolytic macrophages have been implicated in the long-term maintenance of L5178Y cells in a tumor-dormant state in DBA/2 mice. Eventually, however, the tumor-dormant state terminates, and all mice develop ascitic tumors. In an evaluation of the mechanisms involved in termination of the tumor-dormant state, we detected in the peritoneal cavity of many tumor-dormant mice macrophages with increased capacity to suppress the in vitro generation of a secondary anti-L5178Y cell cytolytic T-lymphocyte response. The incidence of macrophage-mediated immunosuppressive activity in individual tumor-dormant mice was related directly to the number of tumor cells in the peritoneal cavity of those mice. Furthermore, in tumor-dormant mice harboring fewer than 5 X 10(4) L5178Y cells, the detection of macrophage-mediated immunosuppressive activity was a prognostic indicator of termination of the tumor-dormant state and development of an ascitic tumor. These data suggest that peritoneal macrophage-mediated immunosuppressive activity, through inhibition of cytolytic T-lymphocyte generation in vivo, contributes to the termination of the tumor-dormant state and development of ascitic tumors.

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PubMed1983

Elimination of L5178Y cells from tumor-dormant DBA/2 mice by specific active immunotherapy.

Cytolytic T-lymphocytes (CTL) can be repeatedly stimulated in L5178Y cell tumor-dormant DBA/2 mice by the i.p. inoculation of 2 X 10(6) X-irradiated L5178Y cells. The restimulated CTL activity has the same kinetics of generation and decline and the same target cell specificity as does the CTL response generated during establishment of the L5178Y cell tumor dormant state. No increase in adherent cell-mediated cytolytic activity or cytolytic or cytophilic anti-L5178Y antibody can be detected after inoculation of irradiated L5178Y cells. The repeated stimulation of CTL activity in tumor-dormant DBA/2 mice results in the elimination of L5178Y cells from a significant number of tumor-dormant mice.

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PubMed1982

Establishment and control of the L5178Y-cell tumor dormant state in DBA/2 mice.

The L5178Y-cell tumor dormant state in DBA/2 mice is an excellent model for assessing immunologically mediated tumor-growth restraint mechanisms associated with establishment and control of a tumor dormant state. It has enabled us to relate components of the host's tumor suppressive immune system to the stage of tumor dormancy and the magnitude of the tumor burden. A strong CTL response has been associated with establishment of the tumor dormant state and can be reelicited in vivo or in vitro, after its initial decline, by reexposure to tumor antigen. This reelicitation is mediated via immunologic stimulation of memory CTL. Combined cultures of NAD T-lineage lymphocytes and macrophages from tumor dormant mice produce considerable cytolytic activity where little or no activity can be detected in the individual populations. Based on the similar pattern of tumor target cell specificity of the two responses, it is likely that memory CTL contribute to this synergistic cytolytic activity. The synergistic cytolytic response persists after CTL activity has waned to undetectable levels and is probably the predominant cytolytic activity associated with maintenance of the tumor dormant state. However, this activity may be obscured by proliferation of endogenous tumor cells, which in turn triggers direct macrophage-mediated cytolytic activity. The target cell specificity of this direct macrophage-mediated cytolytic response is also similar to the CTL response suggesting T cell (or memory CTL) involvement in its generation. The L5178Y-cell tumor dormant model is well suited for attempts at cure with immunotherapy. Active specific and nonspecific immunotherapy are each capable of eliminating all tumor cells from approximately 50% of tumor dormant mice. The L5178Y-cell tumor dormant state is one of several animal models of tumor dormancy. The great variety of growth restraint mechanisms that control tumor dormant states in animal systems is strong evidence that tumor dormant states exist in cancer in human beings.

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PubMed1982

Cross-reacting antigens on L5178Y cells which serve as targets for cytotoxic T-lymphocyte lysis during establishment of the tumor dormant state.

We have attempted to identify the antigen on L5178Y cells that is the target for peritoneal cytotoxic T-lymphocytes (CTL) generated in L5178Y-O (original) immunized and challenged DBA/2 mice during establishment of the L5178Y cell tumor dormant state. These CTL exhibited in vitro lytic activity against methylcholanthrene-induced L5178Y and P815Y cells as well as Gross virus-induced BALB/c cells but not against a variety of other H-2d-tumor cell lines. The pattern of susceptibility to cell-mediated immune cytolysis was identical to the pattern of AB-dependent complement-mediated cytolysis produced by a rabbit anti-L5178Y antiserum. Quantitative expression of surface H-2d determinants was not a limiting factor in tumor cell lysis by CTL. The degree of CTL lysis of the susceptible cell lines was directly related to the amount of tumor-associated antigen expressed on the cell surface. The pattern of in vitro susceptibility to CTL lysis correlated well with in vivo transplantation resistance. The L5178Y cell antigen target for both CTL and Ra-anti-L5178Y serum lysis is likely to be either an endogenous AKR ecotropic viral glycoprotein with a molecular weight of 71,000 or one of two cell surface determinants, at Mr 85,000 and 135,000. These higher-molecular-weight antigens are neither endogenous AKR ecotropic viral-induced nor murine leukemia virus group-specific precursor structural proteins but may be transformation antigens shared by the susceptible tumor cell lines.

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