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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The combined effects of rIL-2 and OK-432 were investigated against a Meth-A tumor, a syngeneic tumor of inbred BALB/c mice. An analysis of the effector cells was also performed. The treatment resulted in an inhibition in vivo of tumor growth and increased survival of the Meth-A tumor-bearing mice. Splenic cells obtained from Meth-A inoculated mice which received combination therapy were not only NK-sensitive YAC-1 and LAK-sensitive EL-4 cells, but also NK-resistant Meth-A cells, as shown in a 4-h 51Cr-release assay. Syngeneic killer cell activity against Meth-A cells was abolished almost completely with anti-Thy 1.2 treatment and about 70% of the activity was abolished with anti-asialo GM1 treatment in a complement-dependent cytotoxic assay. It was not changed by the removal of macrophages and B cells from the splenic cells. Mice which survived for 60 days after the start of therapy rejected Meth-A inoculation when rechallenged, suggesting the establishment of a specific immunity. Combination therapy appeared to be beneficial against Meth-A cells and T-cells appeared to play a determining role in the treated Meth-A bearing mice. It was suggested that more than two populations of killer cells exist in the spleen treated with the combined therapy and they may have the same characteristics as activated T and NK cells with or without specific killer T-cells.
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PMID:Combined effects of intraperitoneal administration of recombinant interleukin-2 and streptococcal preparation OK-432 in murine tumors. 239 Nov 88

Male C3He mice were trained to run on a treadmill (final speed, slope, and duration of 30 m/min, 8 degrees, 30 min/day, 5 days/week, respectively) for 10 weeks or they remained sedentary. At the end of the training program, half of the mice were sacrificed and half were given a single bout of exercise to exhaustion (50% stepwise increases in final running speed for 2-min intervals). Splenic catecholamine concentrations, splenic natural killer cell cytolytic activity against YAC-1 tumor targets, and frequency of asialo GM1 (a murine natural killer cell surface glycolipid)-positive splenocytes were assessed. Exhaustive exercise in both trained and untrained mice reduced the in vitro killing of tumor targets by splenic natural killer cells relative to killing by splenocytes from mice which did not undergo the acute exercise bout (P less than 0.05). The frequency of asialo GM1-positive splenocytes was also reduced in the exhaustively exercised animals (P less than 0.05). Training alone, without the additional stress of exhaustive exercise, reduced the frequency of asialo GM1-positive splenocytes relative to a sedentary condition (P less than 0.05), but did not compromise natural killer cell cytolytic activity against the tumor targets. Splenic epinephrine concentrations in the exhaustively exercised animals were elevated 3- to 5-fold above the concentrations observed in trained and sedentary mice. These results suggest that a single, acute exercise bout reduces the capacity of splenic natural killer cells to kill tumor targets in vitro and that training enhances splenic natural killer cell cytolytic activity, on a per cell basis, against tumor targets.
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PMID:Exercise stress and murine natural killer cell function. 239 54

Tumor infiltrating lymphocytes (TILs) are capable of mediating significant tumor regressions in vitro and in vivo in animal systems. In humans, however, many TIL cell lines are not cytotoxic in vitro, and clinical trials thus far have been less than encouraging. We attempted to correlate TIL cytotoxicity with time of tumor harvest and TIL cell surface antigenic expression. TILs harvested from early MC-38 adenocarcinoma tumors (days 9 and 20 post-tumor implantation), demonstrated significantly higher cytotoxicity against a variety of tumor targets compared to older TILs (days 31 and 37). The younger TILs had a higher expression of the Lyt-1 (Helper T cells), asialo GM1 (NK and T cells), and 49H.8 (NK cells) antigens. Comparison with the MCA-102 sarcoma, a tumor that does not lead to cytotoxic TILs, revealed a low expression of the Lyt-1 antigen on their cell surface. We conclude that TILs cytotoxicity is time-dependent and may be dependent on the presence of Lyt-1+ cells in the overall TIL population of cells.
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PMID:MC-38 adenocarcinoma tumor infiltrating lymphocytes: correlation of cytotoxicity with time of tumor harvest after tumor inoculation. 240 60

A distinct difference in ganglioside composition among various rat ascites hepatomas and Yoshida sarcoma was observed on TLC-immunostaining with anti-fucosyl GM1 antibody, and chemical and enzymatic analyses. Yoshida sarcoma and ascites hepatomas, AH13, AH66F and AH66, but not the other 9 tumor cell lines investigated, specifically contained a disialoganglioside, NeuAc alpha 2-3Gal beta 1-3(NeuAc alpha 2-6)GalNAc beta 1-4Gal beta 1-4Glc beta 1-1ceramide (GD1e), whereas the 9 ascites hepatoma cells without GD1e contained fucosyl GM1. The differential expression of fucosyl GM1 and GD1e in various tumor cell lines indicates that different cell lineages express distinct metabolic pathways for gangliosides, and that the gangliosides are useful markers for distinguishing tumor cell lines.
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PMID:Differential expression of fucosyl GM1 and a disialoganglioside with a NeuAc alpha 2-6GalNAc linkage (GD1e) in various rat ascites hepatoma cells. 242 Jun 39

Spontaneously cytotoxic murine lymphocytes lysed certain cell types infected by herpes simplex virus type 1 (HSV-1) better than uninfected cells. The levels of virus-directed lysis varied widely from target to target, and we found that differences in virus-directed lytic efficiency could be attributed both to the characteristics of HSV-1 replication in the different targets and to the subgroup of natural effector cells which mediated lysis. Although HSV-1 adsorbed to the surface of all the target cells, those in which the virus replicated more efficiently were lysed to a greater extent. As targets, we used cell lines that, when uninfected, were spontaneously lysed by NK cells (YAC-1) or by NC cells (WEHI-164). We also used a fibroblastoid cell line (M50) and a monocytic tumor line (PU51R), which were not spontaneously killed. Using complement-mediated elimination of Qa-5-positive or asialo-GM1-positive NK cells to distinguish NK from NC activity, we found that NK cells lysed HSV-1-infected YAC cells better than uninfected cells, and an NC-like activity selectively lysed HSV-1-infected WEHI cells. In addition, we showed that both NK and NC cytotoxicities contributed to the lysis against the HSV-1-infected fibroblastoid line, M50, but the infected PU51R cells were killed by only NK effectors. These findings were consistent with the results of experiments performed to define the role of interferon in induction of virus-augmented cytolysis. Increased lysis of YAC-HSV and PU51R-HSV was entirely due to interferon activation and was completely abolished by performing the 51Cr-release assay in the presence of anti-interferon serum. Because NC activity was not augmented by interferon, virus-enhanced NC lysis of M50-HSV and WEHI-HSV was not due to this nonspecific mechanism. Together, our data show that HSV-1 infection of NK/NC targets induces increased cytotoxicity, but the effector cell responsible for lysis is determined by the uninfected target, or by an interaction between the virus and target cell, rather than by a viral determinant alone.
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PMID:Enhanced lysis of herpes simplex virus type 1-infected mouse cell lines by NC and NK effectors. 242 Aug 91

More than 80% of BALB/c mice bearing BAMC-1 ascites tumor were completely cured after five consecutive (once every 2 days) i.p. injections of a 0.1 mg dose of OK-432, beginning on day 2 after tumor implantation. The antitumor effect of OK-432 was abolished in athymic nu/nu mice and in anti-thymocyte globulin-treated euthymic BALB/c mice, so although OK-432 treatment did increase the length of survival, all animals eventually died as a result of tumor growth. When peritoneal exudate cells (PEC), obtained on day 12 from OK-432-treated BAMC-1-bearing euthymic mice were evaluated for in vivo tumor neutralization activity, all mice receiving an i.p. injection of the admixture of the nonadherent PEC (1 X 10(7) cells) with BAMC-1 cells (1 X 10(5)) survived for more than 60 days. When the same nonadherent PEC (1 X 10(7) cells) were i.p. transferred adoptively 1 day after the inoculation of 1 X 10(5) BAMC-1 tumor cells, again all mice survived. When these in vivo active PEC were tested for cytotoxicity in vitro against fresh BAMC-1 tumor cells, natural killer (NK) sensitive syngeneic RL male 1, NK-sensitive allogeneic YAC-1 cells, NK-resistant syngeneic Meth-A cells, allogeneic tumor cells (EL4, B16, and P815) and xenogenic human cells, the PEC were found to be capable of lysing BAMC-1 tumor cells together with almost all of the other tumor cells, including NK-resistant cells. Nonadherent PEC contained at least two subpopulations of killer cells. One, directed to syngeneic BAMC-1 cells, was both Thy1.2 and asialo GM1 positive, and another, directed to allogeneic YAC-1 cells, was asialo GM1 positive but Thy1.2 negative. A cold target inhibition assay also suggested the presence of more than two subpopulations. These results indicate that T cells play a determined role in the immunotherapeutic effect of OK-432 on BALB/c mice bearing BAMC-1 tumor, although the participation of activated macrophages could not be excluded. The cells responsible for killing BAMC-1 and other tumor cells appearing in the PEC on day 12 were characterized as containing at least two kinds of lymphokine-activated killer cells.
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PMID:Pronounced antitumor effect of LAK-like cells induced in the peritoneal cavity of mice after intraperitoneal injection of OK-432, a killed streptococcal preparation. 242 68

In addition to allospecific cytotoxic lymphocytes, cytolytic effector cells capable of killing a broad range of targets are generated during mixed leukocyte culture (MLC). These cells, which have been previously called anomalous killer cells, are a distinct functional subset separate from natural killer cells or allospecific cytotoxic lymphocytes but display many characteristics of lymphokine-activated killers. In order to isolate anomalous killer cells for detailed analysis, we generated the cytolytic effectors from an allogeneic MLC using heat-inactivated stimulators. This treatment of the stimulator population abrogated the generation of classical allospecific cytotoxic lymphocytes but allowed the generation of anomalous killer cells which were subsequently cloned via limiting dilution. The clones derived by this method displayed the functional properties of anomalous killers seen in bulk MLCs. The clones demonstrated potent cytolytic activity against both NK-sensitive and NK-resistant tumor targets in vitro and also suppressed tumor growth in vivo. Ultrastructural studies revealed features similar to those of cloned antigen-specific cytolytic cells and clones with NK-like function. The cells expressed surface glycoproteins associated with both NK and T lymphocytes including Thy-1, Ly-2, T200, Qa-5, asialo GM1, and the antigens defined by the NK alloantisera NK-2.1 and NK-3.1. These cells may play an important role during early phases of the immune response, since cytolytic cells of broad specificity may protect the host until classical cytotoxic lymphocytes with restricted specificity are generated.
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PMID:Cloned "anomalous" killer cells derived from allogeneic mixed leukocyte culture. 243 52

The question of the biologic significance of asialo-GM1 (aGM1) expression by a limited number of cells including natural killer cells has been raised by the recent demonstrations that aGM1 is expressed by activated macrophages and activated T cells as well as the proliferating thymoblast and functionally mature subpopulations of thymus. The current report demonstrates that the expression of aGM1 on aGM1-negative lymphocytes can be induced by stimulation with mitogens under activating conditions. In addition, activation of the aGM1-negative tumor lines EL-4/F and P388D1/B1 under conditions that result in interleukin 2 or interleukin 1 production, respectively, also result in a significant increase in aGM1 expression by the tumor cell lines. Expression of aGM1 therefore appears to be associated with events occurring as a prelude to or during activation of effector function. Since the aGM1-negative cells do display sialylated versions of aGM1 which can be converted by neuraminidase treatment into serologically recognizable aGM1, it is suggested that the expression of aGM1 might reflect a change in the level of glycolipid sialylation rather than a change in membrane lipid composition per se. The small percentage of lymphocytes in normal, nonstimulated spleen and thymus populations which express significant levels of aGM1 were sorted and analyzed for total cellular protein and RNA. Increases in RNA synthesis and in total cellular protein and RNA above basal levels of resting lymphocytes are considered indicators of a G0----G1 transition. The aGM1-positive populations displayed a larger mean population size (as indicated both by higher forward light scatter and by higher total cellular protein content), and a higher mean population RNA content than the aGM1-negative populations. These data are discussed in the context of the hypothesis that the expression of aGM1 may be associated with early events in the activation of resting cells which prepare the cells for subsequent induction of effector function.
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PMID:Evidence that expression of asialo-GM1 may be associated with cell activation. Correlation of asialo-GM1 expression with increased total cellular RNA and protein content in normal thymocyte and spleen cell populations. 244 62

Pre-treatment of B16 melanoma cells with recombinant interferon-gamma (IFN-gamma) markedly increased their lung-colonising capacity following i.v. injection into syngeneic mice as compared with control cells. A similar enhancement was observed following the injection of treated cells into athymic nude mice but not in athymic mice carrying the beige mutation. Pre-treatment of syngeneic mice with anti-asialo GM1 antibody effectively abrogated any interferon-induced increase in experimental metastatic activity. The same IFN-gamma treatment significantly increased resistance of B16 cells to splenic natural killer (NK) cell activity as determined by in vitro assays. IFN-alpha/beta pre-treatment of B16 cells decreased sensitivity to NK-cell-mediated lysis to a lesser extent than IFN-gamma and had no detectable effect upon the subsequent metastatic activity of the tumor cells. Class-I antigen expression was altered by these IFN treatments, with IFN-gamma causing dramatic increases in expression of H-2Db antigen, in a pattern consistent with the possibility that increased H-2 antigen expression on B16 cells led to decreased NK-cell sensitivity which was reflected by an increase in experimental metastatic capacity.
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PMID:Interferon-induced alterations in metastatic capacity, class-1 antigen expression and natural killer cell sensitivity of melanoma cells. 244 2

The expression and function of asialo-GM1 (AsGM1) in alloreactive cytotoxic T lymphocytes (CTL) was studied. We have shown previously that the cytotoxic reactions mediated by AsGM1+-cloned CTL were blocked by anti-AsGM1 or by purified AsGM1. To further determine the role of AsGM1 in CTL-mediated cytotoxicity, we examined the correlation between this blocking effect and the expression of AsGM1 on effector and target cells. Now we found that the blocking by anti-AsGM1 was largely dependent on the expression of AsGM1 on the effector cells in a dose-dependent fashion. The expression of AsGM1 on target cells had only little effect on the blocking of cytotoxic reactions by anti-AsGM1 or AsGM1. A threefold difference was seen in the blocking of AsGM1+ and AsGM1- targets. The observation was in sharp contrast to the effectors as no blocking was ever seen with AsGM1- CTL. Similar to CTL effectors, we found that the expression of AsGM1 and L3T4 were mutually excluded on mitogen-activated T cells, despite the fact that they could coexpress in resting T cells. The expression of AsGM1 on CTL effectors was associated with the antigen-nonspecific natural killer (NK)-like or lymphokine-activated killer (LAK)-like activity exerted by the alloreactive CTL. All AsGM1+ CTL possessed LAK activity against antigen-unrelated tumor targets, and the AsGM1- CTL only displayed antigen-specific alloreactivity. The LAK activity was associated with the expression of AsGM1 on effectors, and was not related to the AsGM1 expression on target cells. These findings indicate that the AsGM1 expressed on alloreactive CTL may function as an accessory molecule for T-cell receptors in the antigen-specific alloreactive cytotoxicity mediated by AsGM1+ CTL. The expression of AsGM1 may also be related to the activation of an NK-like apparatus in these CTL. Therefore, AsGM1 not only may be involved in cytotoxic reactions mediated by AsGM1+ CTL, it may also modulate the specificity of the CTL cytotoxicity.
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PMID:Asialo GM1 as an accessory molecule determining the function and reactivity of cytotoxic T lymphocytes. 244 75


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