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

Four-week-old specific-pathogen-free cats were immunized with a combined vaccine composed of killed feline leukemia virus and killed feline oncornavirus-associated cell membrane antigen-containing tumor cells. Immunization induced feline oncornavirus-associated cell membrane antigen antibody titers ranging from 1:32 to 1:256 but did not elicit detectable virus-neutralizing antibody titers. Kittens immunized with tumor cells alone developed higher feline oncornavirus-associated cell membrane antigen antibody titers (ranging from 1:512 to 1:2048) than those given the combined vaccine. All kittens were challenged with virulent Dynder-Theilen feline sarcoma virus at 12 weeks of age. Seventy-five % of the kittens vaccinated with combined vaccine and 67% of unvaccinated control kittens developed progressive fibrosarcomas after challenge. By contrast, none of the kittens vaccinated with killed tumor cells alone developed progressive fibrosarcomas after challenge. The combined vaccine did not, however, inhibit the induction of feline leukemia virus viremia.
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PMID:Abrogation of resistance to feline oncornavirus disease by immunization with killed feline leukemia virus. 6 86

The main findings of the present study are: (a) highly reactive cytotoxic lymphocytes (CTL) against syngeneic and allogeneic murine leukemia cells were generated in vitro in macro 'one-way' mixed leukocyte-tumor cultures (MLTC). Cultures set up in large tissue culture flasks contained up to 400 X 10(6) normal spleen cells (responder cells) and 20--40 X (10(6) mitomycin C-treated leukemia cells (stimulator cells). Successful sensitization in macrocultures was greatly dependent upon the responder cell density and the responder/stimulator cell ratio. Cytotoxic activity, as measured by the 51Cr-release assay, peaked on day 5--7. (b) Sensitized 'memory' lymphocytes produced in primary MLTC could be restimulated with the original tumor cells to give a more rapid and stronger secondary cytotoxic response. (c) lymphocytes sensitized to allogeneic leukemia cells reacted equally well with sensitizing leukemia cells and with the corresponding normal lymphoid target cells, whereas lymphocytes sensitized to syngeneic leukemia cells did not react with the homologous normal lymphocytes. (d) Cryopreserved normal splenocytes and leukemia cells were as efficient as fresh cells in generating allogeneic and syngeneic CTL. (e) Using a Winn-type tumor neutralization assay, it was shown that both allogeneic and syngeneic splenocytes sensitized in vitro to EL4 leukemia (of C57BL/6 mice) and to YAC leukemia (of A mice) were capable of preventing tumor growth in the syngeneic host, whereas cultured normal splenocytes frequently showed a tumor-enhancing effect. Long-term survivors, remaining after inoculation of leukemia cells and sensitized lymphocytes, also became resistant to a tumor challenge that was up to 10,000 greater than the minimum lethal dose.
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PMID:In vitro induction of cell-mediated immunity to murine leukemia cells. II. cytotoxic activity in vitro and tumor-neutralizing capacity in vivo of anti-leukemia cytotoxic lymphocytes generated in macrocultures. 6 86

Electron microscopic, immunologic, and biochemical methods have been used in an attempt to detect and characterize oncornaviruses in human prostatic carcinoma (PCa) and benign prostatic hyperplasia (BPH), and in prostates of mice of high and low mammary cancer or leukemia strains. Ultrastructural examination of 37 PCa and nine BPH specimens has revealed the presence of particles resembling type C virus in five cases of PCa and one of BPH, and also two different types of intracisternal virus-like particles in seven other cases of PCa. Type B virus particles have been observed in prostate of old mice of high mammary cancer strains, while type C virus particles have been found in the prostates of most mice of all the ten strains examined. Immunofluorescence tests with sera from patients with PCa and BPH and with cells derived in vitro from PCa have shown that sera of patients with PCa contained antibodies directed mainly against Forssman-like and tumor-related antigens. In immunofluorescence tests of antisera to major proteins of oncornaviruses with cells of PCa and BPH tissues grown in vitro, positive reactions have been obtained with antisera to p30 protein of murine, feline, and simian type C viruses. Fixed immunofluorescence (FIF) tests of sera of PCa (38%) and BPH (25%) and of some normal donors (27%) gave positive cytoplasmic reaction with mouse prostate cells infected with Soehner-Dmochowski murine sarcoma virus (SD-MSV). Immunoferritin tests of 11 sera positive by FIF gave ferritin labeling of type C virus particles in the SD-MSV-infected mouse prostate cells...
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PMID:Search for oncogenic viruses in human prostate cancer. 6 17

In vivo or in vitro immunity to murine leukemia virus (MuLV)-induced leukemia cells which do not effectively produce virus, has been difficult to demonstrate. Because immunizations with allogeneic murine leukemia cells have been used to confer syngeneic tumor immunity to virus- producing cells, we attempted to generate lymphocytes, cytotoxic to syngeneic nonproducer leukemia cells, by stimulating normal murine spleen cells with allogeneic nonproducer leukemia cells in mixed tumor lymphocyte culture (MTLC) reactions in vitro. Secondary allogeneic MTLC of normal C57BL/6 or DBA/2 spleen cells effectively produced syngeneic tumor-specific cytotoxic lymphocytes. Target cells lysed in lymphocyte- mediated cytolysis (LMC) assays, included both Friend and Rauscher virus- induced syngeneic murine leukemia cells and chemically-induced hematopoietic tumor cells. Syngeneic tumor cells were lysed regardless of whether they produced infectious MuLV or expressed viral antigens gp-71, p-30, or p-12 at the cell surface. Syngeneic normal cells (thymus, lymph node, or Concanavalin A-stimulated spleen cells) used as targets in LMC assays were uneffected by lymphocytes harvested from secondary allogeneic MTLC. Several other in vitro culture treatments including secondary syngeneic MTLC and repetitive mixed lymphocyte culture stimulations were incapable of generating tumor-specific cytotoxic lymphocytes. Based upon these results, we propose that secondary MTLC stimulation of normal spleen cells with allogeneic nonproducer leukemia cells selects for the proliferation of two subpopulations of antigen-specific cytotoxic lymphocytes. The population capable of effecting syngeneic tumor cell lysis is directed against tumor-associated cell surface antigens which may be distinct from viral structural proteins or glycoproteins. The growth of these tumor-specific cytotoxic lymphocytes may be enhanced by a soluble allogeneic effect factor produced by the proliferation of the second subpopulation of lymphocytes generated in repetitive allogeneic MTLC, namely those lymphocytes with specificities directed against differing histocompatibility antigens.
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PMID:In vitro generation of tumor-specific cytotoxic lymphocytes. Secondary allogeneic mixed tumor lymphocyte culture of normal murine spleen cells. 6 3

Northern poke lymphosarcoma DNA polymerase was partially purified from particulate fractions banding at 1.15 to 1.16 g/ml from homogenates prepared from frozen necropsies of tumor-bearing pike. The enzyme behaves as a typical reverse transcriptase, in that it prefers ribotemplates to deoxytemplates. The isoelectric point (pl 5.5) is similar to that of avian myeloblastosis virus polymerase. The pike enzyme elutes from a phosphocellulose column at 0.22 M potassium phosphate, the same as avian myeloblastosis virus DNA polymerase. The enzyme activity is inhibited by pyran, a specific inhibitor of viral DNA polymerases. The most striking difference between the pike lymphoma polymerase and the other viral DNA polymerases tested is the low maximum temperature of 20 degrees, compared to 30 degrees for Rauscher leukemia virus polymerase and 38 degrees for avian myeloblastosis virus and Rous sarcoma virus.
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PMID:Presence of DNA polymerase in lymphosarcoma in northern pike (Esox lucius). 6 92

A type C RNA virus has been detected in the culture fluids of the SU-DHL-1 human histiocytic lymphoma cell line previously established in this laboratory. In electron micrographs, the virus closely resembled other typical mammalian type C RNA tumor viruses in size and morphology. Viral RNA-dependent DNA polymerase activity has been demonstrated in particles (densities of 1.15 and 1.22 g/ml) in the microsomal cytoplasmic fraction and in pellets of culture fluids. The enzyme is partially inhibited by antibodies to the RNA-dependent DNA polymerases of simian sarcoma virus and RD-114 virus but not by antibody to the polymerase of murine leukemia virus, suggesting some degree of relatedness to type C viruses of subhuman primate origin. Typical syncytial microplaques were induced when SU-DHL-1 cells were cocultivated with rat XC cells. Although no focus formation was noted in similarly cocultivated mouse UC1-B cell cultures, the numbers of foci induced in rat embryo fibroblasts by murine sarcoma virus were significantly increased by coinfection with the virus from SU-DHL-1 cell culture fluids. No other evidence of infectivity, inducibility, or capacity for helper rescue of defective murine sarcoma virus genomes has been detected to date in cocultivation studies with a spectrum of fibroblastic and other nonlymphoid indicator cell lines of human and other species of origin.
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PMID:Isolation of a type C RNA virus from an established human histiocytic lymphoma cell line. 7 39

Similarities have been observed for some time between oncornavirus-induced malignancies in laboratory animals and leukemias and solid tumors in man. Particles similar to type C oncornaviruses have been detected by electron microscopy both in cells or plasma from leukemia patients and in solid-tumor human malignancies such as Hodgkin's lymphoma, lymphosarcomas, and sarcomas. Likewise, particles resembling type B oncornaviruses in shape and appearance have been found in human breast cancer. In neither case has the infectious nature of the particles been confirmed. However, DNA synthesized in vitro by the enzyme of murine mammary tumor virus was found to hybridize with polysomal RNA obtained from human mammary adenocarcinomas. The presence of RNA complementary to RNA from the Rauscher strain of murine leukemia virus has been observed in other human malignancies unrelated to breast cancer. It has also been found that cells of patients with myelogenous leukemia possess an oncornaviral-type reverse transcriptase that is distinguishable from other cell DNA polymerases and serologically related to the reverse transcriptase of primate oncornaviruses.
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PMID:Human studies following animal models of tumorigenesis by oncornaviruses. 7 Nov 81

Five main structural polypeptides of Friend murine leukemia virus, a typical C-type RNA tumor virus, have been isolated. Their localization within the particle was attempted. They range from 10,000-71,000 in molecular weight and display three kinds of immunological determinants. The major envelope glycoprotein binds to cellular receptors and elicits the formation of antibodies which neutralize the virus and kill virus producing tumor cells in vitro. Natural as well as artificial immunity to this component protects mice against virus induced leukemia.
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PMID:[Structural proteins of C-type RNA tumor viruses. Properties and significance for tumor immunity]. 7 34

Inbred strain 2 guinea pigs immunized with L2C leukemia cells produced antibodies to L2C cells detected by 125I-protein A assay. L2C-associated tumor antigens were reacted with syngeneic antisera and analyzed by immunoprecipitation and SDS-polyacrylamide gel electrophoresis. These sera recognized idiotypic determinants on surface IgM molecules of L2C cells but did not recognize any determinants on normal strain 2 spleen cells. Thus, determinants on IgM molecular act as tumor-associated antigens in the L2C system and can be detected by syngeneic sera.
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PMID:Identification of a tumor-associated antigen of the guinea pig L2C leukemia by using syngeneic antisera. 7 93

An experimental procedure for detecting and characterizing tumor-associated, virion, and histocompatibility antigens has been developed. The method takes advantage of the high resolution that proteins, solubilized by Triton X-100 and reduced, display after sodium dodecyl sulfate gel electrophoresis. The antigens can be detected as distinct molecular weight species by a highly sensitive inhibition of cytotoxic reaction. When coupled to the lactoperoxidase-catalyzed iodination of intact cells, the procedure permits the determination of externally exposed antigens. In the present study, the method has been applied to the Moloney leukemia virus-induced YAC lymphoma cells of strain A mice, which express a Moloney leukemia virus-determined cell surface antigen (MCSA) in addition to the type C viral proteins gp71, p30, p15, p15(E), p12, and p10. MCSA was identified as an exposed surface protein distinct in size and antigenic determinants from the major envelope and core protein of Moloney leukemia virus and the histocompatibility antigens. Multiple molecular weight species possessing antigenic determinants for MCSA, gp71, and H-2(a) have been detected. These results provide direct confirmation that MCSA is unrelated to the known virion structural proteins or to the H-2(a) antigen. This method should permit the direct identification and molecular weight characterization of any antigen whose determinants are not solely dependent on a complex quaternary structure and for which serological reagents are available.
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PMID:Moloney leukemia virus-induced cell surface antigen: detection and characterization in sodium dodecyl sulfate gels. 7 31


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