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H Pelletier

Publications and source records attributed to H Pelletier.

At least 37 records · Page 2Linked to original sources
PubMed1989

Comparative effect of rat and fetal calf serum on measurement of the natural tumoricidal activity of rat lymphocytes, macrophages and polymorphonuclear cells.

The effect of rat serum versus fetal calf serum on the in vitro natural cytolytic activity of rat lymphocytes, macrophages and polymorphonuclear cells against syngeneic tumour cells was compared. The cytolysis level mediated by the three varieties of effector cells was lower when rat serum was used instead of fetal calf serum to supplement the culture medium. This could explain in part the discrepancies found between in vitro and in vivo studies.

Animals↗
PubMed1989

Effects of cyclosporin A on progressive and regressive tumors induced by two cancer lines derived from a single colon carcinoma chemically induced in the rat.

The effects of cyclosporin-induced immunosuppression were assessed in a rat model of progressive and regressive colonic tumors. Two cloned cell variants, obtained from the same chemically induced colonic carcinoma, differ in their capacity to grow when injected into the syngeneic rat. PROb cells yield progressive tumors and often metastases; in contrast, REGb cells produce tumors which regress in 3 to 6 weeks. Cyclosporin A (CsA) administered daily, 20 mg/kg subcutaneously (s.c.) for 30 days after tumor cell inoculation, drastically enhanced the local growth of PROb tumors and increased the number of metastases. It increased the local growth and prevented the regression of REGb tumors which persisted even as long as 8 weeks after the termination of CsA administration and occasionally yielded metastases. CsA prevented the accumulation of inflammatory cells with the T lymphocyte phenotype at the periphery of both PROb and REGb tumors but did not alter the tumor infiltration by macrophages and NK cells. CsA did not modify the natural cytotoxicity of peripheral blood mononuclear cells against PROb and REGb target cells. These results suggest that CsA-induced suppression of T lymphocyte activity may enhance tumor progression and suppress tumor regression in this model.

Animals↗
PubMed1989

Histoimmunological characterization of the cellular reaction to liver metastases induced by colon cancer cells in syngeneic rats.

Artificial liver metastases were produced by injecting in vitro cultivated colonic cancer cells into the mesenteric vein of syngeneic rats. An immunohistologic study of the inflammatory host cells infiltrating the tumors was carried out from 1 to 46 days after tumor cell injection, using a set of monoclonal antibodies labelling tumor cells, macrophages or lymphoid cells subpopulations. In small metastases, 3-7 days after tumor cell injection, tumor cell foci were surrounded by a dense corona of inflammatory cells, predominantly T lymphocytes and NK cells. This inflammatory corona regressed when metastases grew larger and completely disappeared around the large metastases found more than 28 days after cell injection. Inside the metastases, the tumor cells were mixed with a small number of cells with the characteristic labelling of macrophages (KiM2R+, W3/25+); however, the inside macrophages are OX8+ in contrast to macrophages found in normal liver and in the peritumoral corona. The progressive disappearance of the coronal inflammatory cells suggests that cancer cells are able to produce or to induce other cells to produce anti-inflammatory agents inhibiting the accumulation of macrophages and lymphoid cells around the tumors.

Animals↗
PubMed1988

Specificity of the immune response leading to protection or enhancement by regressive and progressive variants of a rat colon carcinoma.

Two cell clones, K12/TRb (PROb) and K12/TSb (REGb), have been isolated from the same serially transplantable tumor, DHD, established from a colon carcinoma chemically induced in the rat. Inoculation of REGb cells gives a tumor which regresses within 4 to 8 weeks and generates immune protection against subsequent injection of the progressive tumor cells, PROb. Inoculation of PROb cells gives a progressive tumor and generates tolerance allowing progressive growth of contralaterally injected REGb cells. Inoculation of REGb cells fully protects the host against growth of a DHD tumor graft, the tumor from which REGb and PROb cells were originally obtained. On the other hand, inoculation of REGb cells does not confer any protection against growth of 4 other syngeneic tumor grafts, DHA, DHB, DHC and DHE. These tumors were obtained from other colonic tumors induced as DHD by 1.2 dimethylhydrazine (DMH). Progressive growth of the tumor induced by inoculation of REGb cells is observed in animals bearing a contralateral DHD tumor, but not in animals bearing tumor from other transplantable lines, DHA, DHB, DHC and DHE. Our results show that immune enhancement of a regressive tumor and the immune protection that it confers constitute specific responses to a tumor-specific transplantation antigen present on a single transplantable colon tumor.

Adenocarcinoma↗
PubMed1988

Differential sensitivity to natural cell-mediated cytotoxicity of two rat colon adenocarcinoma variants differing in their tumorigenicity: identification of the effector cells as natural killer cells.

DHD/K12 TRb (PROb) and DHD/K12 TSb (REGb) are two cancer cell variants originating from the same rat colon adenocarcinoma. They differ in their tumorigenicity: when inoculated into syngeneic BDIX rats, PROb cells induce progressive tumors whereas REGb cells induce tumors which always regress. As previously described, there is an inverse relation between their tumorigenicity and their susceptibility to NCMC mediated by syngeneic spleen or peripheral blood lymphocytes: PROb cells are significantly less sensitive to NCMC than REGb cells. This suggests a role for NCMC in the regression of REGb tumors. In this work the BDIX NCMC effector cells active in vitro against REGb cells were identified as NK cells according to four criteria: (1) efficacy in a 4-h 51Cr release assay, (2) sensitivity to anti-asGM1 antibody plus complement, (3) LGL morphology, and (4) ability to bind with the same affinity REGb and YAC-1 cells. In spleen, these NK cells were heterogeneous with respect to their asGM1 surface density and their morphology. PROb cells were not lysed by these NK cells in a short-term cytotoxicity assay, but only in a 16-h assay. It was shown that PROb and REGb cells were bound with the same affinity by NK cells, thus they certainly differ in their ability to resist to NK lytic mechanisms. This difference could play a role in the different tumorigenicity of the two variants.

Adenocarcinoma↗
PubMed1988

Regression induced by lentinan, of peritoneal carcinomatoses in a model of colon cancer in rat.

Lentinan has been tested in a model of colon cancer in rats. Peritoneal carcinomatoses were induced in BDIX rats by i.p. injections of syngeneic cells isolated from a colon carcinoma, and established in a permanent cell line. The treatment consisted of five i.p. injections, 2 days apart, of 2 mg lentinan/kg at a concentration of 200 micrograms/ml. This was started on day 14 after tumor cell injection, when the rats bore numerous nodules of 1-5 mm. Lentinan significantly inhibited the growth of carcinomatoses. Eleven out of the 20 rats treated with the best lentinan therapy were tumor free at autopsy on day 42. Lentinan significantly increased the life span of carcinomatous rats. The half life following tumor cell injection was 42 days in the control and 70 days in the treated group. Four out of 10 treated rats were still alive on day 210. They were tumor free at autopsy, whereas all the controls died between the 40th and the 70th day. The effectiveness of lentinan was dependent on the number and frequency of the injections. A dose effect was obtained and a strong influence of the concentration was shown.

Animals↗
PubMed1987

Effects of a single injection of anti-asialo GM1 serum on natural cytotoxicity and the growth of a regressive colonic tumor in syngeneic rats.

The REGb tumor cell line is a cloned variant of the DHD-K12 cell line, established from a colon carcinoma chemically induced in the rat. Unlike the parent DHD-K12 cell line, or other clones, which give progressive tumors when inoculated to the syngeneic rat, REGb cells produce tumors which regress in 3 to 5 weeks and never cause metastasis. In order to explore the role of natural killer (NK) cells in REGb tumor regression, each rat was given one injection of anti-asialoGM1 (anti-asGM1) serum, a known inhibitor of NK activity. This injection was done 24 hr before REGb cell challenge. This injection significantly depressed the in vitro cytotoxicity of peripheral blood lymphocytes on REGb cells for 2 weeks. REGb tumors grew larger and regressed later in the treated animals than those in the controls. Furthermore, a progressive or recurrent tumor was observed in 4 out of 10 treated rats, giving lung and/or lymph-node metastases in 2 cases. Immuno-histological study of the cells infiltrating the REGb tumors in control and treated animals showed a decrease number of asGM1+ and OX8+ lymphocytes, presumably NK cells, after anti-asGM1 treatment. An increase in number of macrophages was demonstrated in the progressive tumors of treated animals. These results suggest that NK cells play an important role in the initial stage of the regression TSb tumors in untreated syngeneic rats.

Animals↗
PubMed1987

An immunohistological study of cells infiltrating progressive and regressive tumors induced by two variant subpopulations of a rat colon cancer cell line.

In order to understand the mechanisms leading up to progression or regression, tumors resulting from the s.c. inoculation of progressive or regressive variants of a cell culture established from a chemically-induced rat colonic carcinoma were subjected to sequential histological study. As immunological factors have been previously described in this system of progressive or regressive tumors, special interest was given to inflammatory cells, T and B lymphocytes and macrophages, located inside and outside the tumor. Immunohistological methods using monoclonal or polyclonal antibodies and enzyme histology were performed to identify different populations of infiltrative cells. In both variants of tumors an accumulation of these cells were seen at the periphery of the tumor, surrounding the nodules. In contrast, very few inflammatory cells, macrophages or T lymphocytes were seen inside the clumps of tumor cells where cytolytic cells could have a contact-dependent tumoricidal effect. Only small differences were found between progressive and regressive tumors in the density of the various populations of T helper, T cytotoxic/suppressor, B lymphocytes or macrophages inside or around the tumor nodules. On the other hand, progressive and regressive tumors clearly differ in the relationship between tumor cells and the fibroblastic reaction they induce. Regressive tumors were rapidly encircled by a fibroblastic reaction isolating them from the peripheral tissues. The fibroblastic reaction was less dense around the progressive tumor cells which were able to migrate and invade the periphery. This suggests that immunological factors leading to tumor progression or regression could act indirectly through a control of the fibroblastic reaction, rather than through a direct cytotoxic effect on the tumor cells.

Animals↗
PubMed1987

In vitro natural killer activity against progressive and regressive variants of a rat colon adenocarcinoma. Effect of treatments with anti-asialo GM1 plus complement.

In a previous work, a cell line (DHD/K12) was established from a colon adenocarcinoma induced in a BDIX rat by 1,2-dimethylhydrazine. From this line, two cloned sublines, PROb and REGb, were then isolated. When subcutaneously inoculated into syngeneic rats, PROb cells yield progressive tumors, whereas REGb cells yield tumors which regress. In this study, in a 16-h 51Cr release assay, natural cytotoxicity mediated by BDIX splenic nonadherent lymphoid cells (NK cells) was shown to be much higher against REGb cells than against PROb cells. Whatever the target cells, NK cytotoxicity was always higher when the effector cells were obtained from males rather than from females. Treatment of BDIX splenic lymphocytes by anti-asGM1 serum plus complement revealed that both anti-asGM1 sensitive and non-sensitive NK cells exist. The activity of anti-asGM1 non-sensitive NK cells appeared to be minor and to be detected only when the level of cytotoxicity before treatment was sufficiently high. The difference between PROb and REGb tumor growth appears to be linked, at least in part, to a higher sensitivity of REGb cells to NK cells and especially to anti-asGM1-sensitive NK cells.

Adenocarcinoma↗
PubMed1987

Lack of effect of a high polyunsaturated fat diet on the growth of transplantable colon tumors and on the cytolytic activity of macrophages in rats.

The effect of a high dietary level of polyunsaturated fat was tested on the growth of three different colon cancer cell lines injected subcutaneously into syngeneic rats. This effect was also tested on the in vitro cytolytic activity of resident peritoneal macrophages, natural or endotoxin and/or indomethacin-modulated. A 12% corn oil dietary supplement had no effect in any of the cases tested.

Animals↗
PubMed1987

Treatment with endotoxins of peritoneal carcinomatosis induced by colon tumor cells in the rat.

Peritoneal carcinomatosis, a common spreading of human colon carcinoma, can be obtained by intraperitoneal injection of colon tumor cells in rats. When BDIX rats are injected with 10(6) syngeneic tumor cells, isolated and cloned from a chemically induced colon carcinoma, they die within 2-3 months with solid peritoneal tumors and hemorrhagic ascites. Repeated intraperitoneal injections of 20 micrograms endotoxins (Escherichia coli W0128:B12) from day 3 after tumor cell challenge inhibited tumor growth. This effect was long-lasting since 7 out of 10 treated rats were still alive and tumor-free 6 months after tumor cell challenge. When the endotoxins were administered from day 15 after the tumor cell challenge, in rats with established tumors visible with the naked eye, the survival times were significantly increased, and 6 out of 30 treated rats were still alive and tumor-free 6 months after tumor cell challenge. The optimum effect was obtained with 5 repeated injections. The different frequencies of injection tested, i.e. 1, 3 or 5 days apart were equally effective. Endotoxins were ineffective when administered intravenously. No side effect was observed.

1,2-Dimethylhydrazine↗
PubMed1985

[Kinetic study of antitumor lymphocyte cytotoxicity in rats bearing progressive or regressive syngeneic colonic tumors].

In order to perform a kinetic study of the antitumor lymphocyte-mediated cytotoxicity in syngeneic BDIX rats bearing progressive (TRb) or regressive (TSb) colonic tumors, the 51Cr release assay was adapted to this experimental model. Two groups of 72 rats were inoculated with TRb or TSb cells. Results failed to show any clear and univocal evolution of lymphocyte cytotoxicities against TRb or TSb cells. On the other hand these cytotoxicities were roughly at the same level than natural cytotoxicity (normal rats), and were always higher against TSb than TRb cells.

Adenocarcinoma↗
PubMedDate not supplied

Serum concentrations of amiodarone required for an in vivo modulation of anthracycline resistance.

We demonstrated previously that amiodarone is able to circumvent in vitro the inherent resistance to anthracyclines of the DHD/K12 rat colon cancer cell line. We have now determined in the rat the amiodarone seric concentrations required to enhance the in vitro cytotoxicity of 4'-deoxydoxorubicin (deoDX) against DHD/K12 cells. A maximal deoDX potentiation was obtained in vitro when anthracycline was diluted in the serum of rats receiving at least 75 mg/kg of intravenous amiodarone resulting in seric concentrations of more than 40 micrograms/ml. In patients treated with amiodarone, the mean serum concentrations were 0.9 +/- 0.1 microgram/ml after an one month's oral administration of 200 mg/day, 2.2 +/- 1.0 micrograms/ml after a 24 hr continuous infusion of 300 to 900 mg/day and 5.4 +/- 1.1 micrograms/ml after a brief 3 hrs infusion of 450 mg amiodarone. Such amiodarone concentrations in human serum are much lower than those necessary to produce a significant anthracycline potentiation. In rats receiving amiodarone at a maximal tolerated dose (100 mg/kg) minutes before the injection of 10 mg/kg doxorubicin (DX), we observed an increased accumulation of the anthracycline in the liver and kidney compared to rats receiving DX alone. The DX content was not modified by amiodarone in the other organs studied (heart, lung, spleen and pancreas). An amiodarone pretreatment accelerated the death of rats receiving 5 or 10 mg/kg DX did not provoke lethality for a lower dose of 2.5 mg/kg DX. The very high doses required and the risk of increased toxicity seem to preclude the use of amiodarone for the modulation of anthracycline resistance in cancer patients.

Adjuvants, Pharmaceutic↗
PubMedDate not supplied

Involvement of effector cells in the treatment with endotoxins of peritoneal carcinomatosis induced by colon tumour cells.

Peritoneal carcinomatoses, an ordinary way for human colon carcinoma to spread, are incurable. When rat peritoneal carcinomatoses of colon origin were treated with endotoxins i.p. administered 3 days after the tumour cell injection, 70% of the BDIX rats were alive 30 weeks after the PROb tumour cell injection whereas all the untreated rats died of their tumour within 14 weeks. The study of the effector cells involved in the antitumour effect of endotoxins suggests that T lymphocytes are required for this effect. The endotoxin effect is local and is not reflected by the cytolytic activity of peritoneal cells.

Adenocarcinoma↗
PubMedDate not supplied

Use of a specific monoclonal antibody for studying the liver metastatic invasion of a rat colon cancer.

A simple model for liver metastasis from colon cancer resulted from the intraportal injection of 2 x 10(7) highly tumorigenic DHD/K12/PROb cells into syngeneic BDIX rats. Early detection and development of cancer invasion were studied by conventional microscopy and immunoenzymatic staining using a specific monoclonal antibody. Metastases developed either from isolated cancer cells early disseminated in sinusoid network or from intraportal microthrombi. An intense immune reaction developed until day 15 after injection but decreased and disappeared at the latest stages of evolution.

Animals↗
PubMedDate not supplied

In vivo and in vitro effects of fish-containing diets on colon tumour cells in rats.

Polyunsaturated n-3 fatty acids, abundant in sea fish, can inhibit the growth of chemoinduced or transplanted mammary tumours in the rat. Since mammary and colonic cancers have both been linked to a high fat consumption, we studied the effect of 2 diets moderately (7% fish meal) or strongly (9% fish oil) enriched in fish fatty acids on the growth of colon cancer cells subcutaneously inoculated into syngeneic rats. The diets had no effect on the in vivo tumor growth and on the in vitro tumouricidal activity of peritoneal macrophages or splenic lymphocytes.

Animals↗