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

New antigenic specificities, not detectable on parental cells and transmissible after the withdrawal of the drug treatment, have been induced in mouse lymphomas. Studies were conducted of proliferative stimulation of syngeneic lymphocytes and the generation of cytotoxic lymphocytes (CL's) in a mixed lymphocyte-tumor cell culture system by 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC)-induced antigens in L1210 and EL4 leukemia sublines. The DTIC-induced antigens were observed to stimulate [3H]thymidine uptake by normal and primed syngeneic lymphocytes and to generate specific CL's to DTIC-altered cells. The specificity of the in vitro immune reactivity was demonstrated. Characteristics of lymphocyte triggering, including the optimal ratio of stimulating cells to responding cells, the kinetics of CL activation, and the quantitation of CL activity, were also evaluated. DTIC antigens on leukemic cells can activate syngeneic lymphocytes and can act as target antigens in cell-mediated immunity. The experimental data support the transplantation antigen-like nature of DTIC-induced antigens.
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PMID:In vitro lymphocyte stimulation and the generation of cytotoxic lymphocytes with drug-induced antigenic lymphomas. 7 62

Previous studies from this laboratory have mapped resistance and/or susceptibility to radiation-induced leukemia virus (RadLV)-induced neoplasia to the H-2D region. H-2 linked effects on virus replication can be detected subsequent to the initial virus infection, and clear-cut differences in numbers of virus infected thymus cells can be detected as early as 5 wk after RadLV inoculation. Rapid increases in cellular synthesis and cell surface expression of H-2 antigens are detectable immediately after virus inoculation. These changes have been studied by immunofluorescence, absorption, cell surface iodination followed by sodium dodecyl-sulfate-polyacrylamide gel electrophoresis, and two dimensional gel electrophoretic analysis of internally labeled lymphocyte proteins. Expression of H-2K molecules is significantly increased in cells of susceptible and resistant animals. However, significant increases in expression of H-2D antigens occurs only on thymus cells from resistant strains (H-2Dd). Transformed cells of resistant and susceptible H-2 haplotypes adapted to tissue culture lack detectable H-2 antigens as determined by serological absorption studies. It is argued that altered expression of H-2 antigens plays a very significant role in the mechanism of host defense to virus infection.
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PMID:Increased synthesis and expression of H-2 antigens on thymocytes as a result of radiation leukemia virus infection: a possible mechanism for H-2 linked control of virus-induced neoplasia. 7 39

Agarose microdroplet leukocyte migration inhibition (LMI) assays were performed to measure reactivity against line 10 hepatocarcinoma antigens and purified protein derivative (PPD) with the use of peripheral blood leukocytes from line 10 and/or BCG-sensitized syngeneic guinea pigs. The assay was quite sensitive and detected leukocyte migration inhibition with concentrations as low as 12.6 ng protein/ml of the crude sonicate of the line 10 tumor and 0.1 pg PPD. Specificity was shown by lack of reactivity in leukocytes of line 10 and/or BCG-sensitized animals with antigen preparations of L2C leukemia cells or normal syngeneic liver. Furthermore, leukocytes from normal control guinea pigs failed to react with any antigen. The results also suggested antigen cross-reactivity between line 10 tumor and BCG. Leukocytes from guinea pigs sensitized to only BCG became LMI reactive to the line 10 sonicate as well as PPD. No reactivity was observed with leukocytes of the animals in simultaneous tests with a sonicate of guinea pig L2C leukemia cells. The results demonstrated the usefulness of this microassay in detection of LMI reactivity with low antigen concentrations and small volumes of whole blood.
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PMID:Leukocyte migration inhibition of tumor antigen and purified protein derivative reactivity in guinea pigs sensitized to line 10 hepatocarcinoma and BCG. 7 70

Methylcholanthrene-induced sarcomas of BALB/c mice express unique tumor specific transplantation antigens (TSTA), and weaker, common TSTA. Antigens of endogenous murine leukemia virus (MuLV) expressed by some of these tumors cannot completely account for these common TSTA. However, MuLV antigens on the immunizing tumor appear to increase the immunogenicity of the common TSTA.
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PMID:Unique and common tumor-specific transplantation antigens of chemically induced mouse sarcomas. 7 55

This article concerns the molecular mechanisms by which RNA tumor viruses, commonly called as oncornaviruses, transfer their genetic information from the genomic RNA (70 s RNA) of the virions to the cellular DNA, leading to neoplastic transformations. The article describes biochemical and serological properties of reverse transcriptase, its role in the life cycle of RNA tumor viruses and broader implications to molecular biology. In this connection, the authors report their own findings on the role of reverse transcriptase in a preleukemic disease, myelofibrosis. This enzyme, discovered in their laboratory, is antigenically closely related to reverse transcriptase of certain primate RNA tumor viruses, and of human leukemic cells. The article also describes the role of reverse transcriptase inhibitors in viral oncogenesis. Of particular interest, is the partially thiolated polycytidylic acid (MPC) which has been developed by the authors, and is known to have a very high binding affinity to the viral reverse transcriptase. The implication of these basic data on the clinical effectivity of MPC in human leukemia, documented in a few cases, has been discussed.
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PMID:[Molecular biological aspects of oncogenesis caused by RNA tumor viruses (author's transl)]. 7 88

A tumor-associated transplantation antigen (TATA) from guinea pig L2C leukemia cells was solubilized by different methods. It was found that the 3 M KCl extraction yielded the most immunogenic TATA of L2C cells. Immunization of normal strain 2 guinea pigs with this extract in complete Freund's adjuvant gave complete protection against a subsequent challenge with tumor cells. Further fractionation of the KCl extract of L2C cells by Sephadex G-200 chromatography suggested that the immunogenic activity was present in the fraction containing materials with estimated m.w. of less than 20,000 daltons.
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PMID:Solubilization and partial characterization of a tumor-associated transplantation antigen of the guinea pig L2C leukemia. 7 74

The existence of a nonvirion tumor-associated cell surface antigen (TASA) on cells transformed with Friend (FLV) on Rauscher (RLV) leukemia virus has been difficult to demonstrate. Antisera raised against classically defined Friend- Moloney-Rauscher antigenic determinants have been shown to react with virus structural proteins coded for by genetic information contained in the lymphatic leukemia or helper (LLV) virus genome. The recent development of nontrans-formed fibroblast cell lines which contain the replication-defective spleen focus-forming virus (SFFV) genome, free of replicating LLV, has allowed investigation of an SFFV-specific antigen. We have applied the techniques of mixed tumor-lymphocyte culture stimulation followed by lymphocyte-mediated cytolysis assays to search for the cell surface expression of an antigen coded expressly by SFFV genetic information. SFFV nonproducer-immune, in vitro activated spleen cells were capable of effecting the lysis of SFFV-containing BALB/c 3T3 and Fischer rat epithelial, cloned cell lines. Normal BALB/c 3T3 and BALB/c 3T3 cells infected with three types of ecotropic LLV were unaffected. Syngeneic FLV and RLV-induced murine leukemia cells were also killed by SFFV nonproducer-immune lymphocytes. In addition, Kirsten sarcoma virus-transformed, replication-defective and replication-rescued BALB/c 3T3 fibroblasts were not susceptible to SFFV antigen-directed cytolysis. Antibody-dependent complement-mediated cytolysis assays using monospecific goat antisera confirmed that SFFV nonproducers lacked cell surface expression of virion structural proteins. These observations suggest that the antigen detected in LMC experiments was not coded for by genetic information contained in the helper component of FLV, and that it represents a true SFFV-specific cell surface antigen. Based upon the recent molecular evaluation of the SFFV genome as consisting of both xenotropic and ecotropic virus sequences, it appears reasonable that xenotropic genetic information may be responsible for expression of the SFFV- specific antigen. Since the replication-defective SFFV genome is also responsible for the malignant transformation associated with FLV-induced erythroleukemia, one might postulate that gene sequences capable of programming transformation may also code for the TASA detected in these studies.
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PMID:The detection of a spleen focus-forming virus neoantigen by lymphocyte-mediated cytolysis. 7 57

Previous studies have demonstrated that the Rauscher virus induces a biphasic erythroleukemia in DBA mice, and the regression of the disease is connected with the appearance of antibody-dependent cellular cytotoxicity. In the present work, attempts were made to reveal the mechanism leading to the lethal exacerbation of the leukemia. In the sera of leukemic mice soluble tumor-specific antigen could be demonstrated in the stages of early progression and regression but not in the stage of exacerbation. The antigen was present in form of immune complexes with free antibodies in excess. The emergence of a new population of leukemia cells has been observed during the stage of regression. On the surface of these cells the antigen receptor sites were masked by sialic acid which resulted in the loss of immunosensitivity and immunogenicity.
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PMID:Immune response to Rauscher virus-induced leukemia in DBA mice. II. Correlation between antigenic expression and pathogenesis. 7 84

Among 106 patients with Hodgkin's lymphoma in stage IIIB and IVB treated from September 1969 to June 1977 by a working team for hematology and oncology at the clinic and outpatients clinic of the Medical School of Erfurt, there were two cases (=1.9%) showing a final transition to leukaemia with immature cells. A third neoplasia which had developed in a former field of irradiation was additionally observed in one patient. The various possibilities arising from an oncologic effect of ionizing rays and those substances having a cytostatic effect are discussed. After frequent reports on the occurrence of secondary tumours following intensive radiological and cytostatic therapy of advanced Hodgkin's lymphoma the enhanced risk of a secondary tumour being induced by this combined therapy cannot be excluded. Various conclusions are drawn from that by the authors.
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PMID:[The appearance of immature cell leukemias after radiologic and cytostatic intensive therapy of Hodgkin's lymphoma]. 8 Mar 62

The antitumor activity of tallysomycins A and B was determined in five experimental tumor systems in mice. Tallysomycins A and B were highly active against B16 melanoma, sarcoma 180 ascites tumor and Lewis lung carcinoma, and moderately active against P388 leukemia but were without effect on lymphoid leukemia L1210. The antitumor activity of tallysomycin A was 2 to 3 times that of tallysomycin B and 3 to 17 times that of bleomycin. Tallysomycin A was about 1.5 and 4 times more toxic for mice than tallysomycin B and bleomycin, respectively, in terms of subacute LD50 values.
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PMID:Tallysomycin, a new antitumor antibiotic complex related to bleomycin. III. Antitumor activity of tallysomycins A and B. 8 Apr 2


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