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

We recently described a factor, costimulator, that is required for the concanavalin A-induced proliferation of CBA mouse thymocytes in vitro (see Reference 1). Using the costimulator dependence of mouse thymocytes as an assay, we have now determined that spleen cells from congenitally athymic (nude) BALB/c mice do not produce costimulator in response to Con A, and spleen cells depleted of Thy 1-positive cells do not respond to it in the presence of Con A. Thus, costimulator both requires thymus-derived (Thy 1+ lymphocytes for its production and has an effect on this type of cell. (However, the costimulator-producing and responsive cells may be different.) Purified costimulator preparations are a source of the required second component for the stimulation of adult, CBA/J thymic lymphocytes by PHA, normally a poor mitogen for these cells. They also enhance the level of DNA synthesis in a mixed leukocyte reaction, and the specific generation of cytotoxic lymphocytes to allogeneic tumor cells in vitro. Costimulator is not H-2 restricted in its effects, and it is produced in mixed leukocyte reactions. Finally, it has been possible to grow normal, primary thymic lymphocytes in culture for about 20 days by adding partially purified costimulator to the cultures.
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PMID:Effects of costimulator on immune responses in vitro. 14 74

The oxidative phosphorylation and ATPase activity (initial and stimulated by DNP and Mg2+) in tumor mitochondria were investigated. The intact mitochondria of Zajdela hepatoma, in contrast to liver mitochondria, exhibit the ATPase activity which is slightly stimulated by 2,4-dinitrophenol and is markedly activated by Mg2+. The mitochondria from transplantable solid tumors (adenocarcinoma 755, Iensen sarcoma, sarcoma 45) despite satisfactory morphological integrity under electron microscopy are biochemically less intact than the mitochondria of hepatoma. ATPase of these mitochondria is also slightly stimulated by 2,4-dinitrophenol and significantly by Mg2+. The ATPase activity of thymus mitochondria, the normal tissue with sufficiently high proliferative activity, corresponds to that of tumor mitochondria. The total amount of enzyme in mitochondria of tumors investigated and thymus is not lowered, since the ATPase activity in the presence of both DNP and Mg2+ corresponds to the ATPase activity of liver mitochondria. The Mg2+ ATPase activity of tumor mitochondria is not sensitive or is only partly sensitive to oligomycin. The data obtained are indicative of a high lability of the phosphorylating system in tumor and thymus mitochondria. A possibility of reorganization of the energy mechanism of tumor mitochondria and some normal tissues in connection with increased metabolism requiring high energy consumption, is discussed.
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PMID:[Some peculiarities of ATPase in tumor mitochondria]. 15 49

The effect of specific priming with alloantigens on the frequency of cytolytic T lymphocyte precursors (CTL-P) has been investigated. Alloimmune lymphoid cells were obtained from the spleen of C57BL/6 (H-2b) mice primed with DBA/2 (H-2d) tumor cells or from 14-day unidirectional mixed leukocyte cultures (C57BL/6 anti-DBA/2). CTL-P frequencies directed against H-2d alloantigens were estimated by limiting dilution analysis in a sensitive micro MLC system. Under these conditions, an apparent increase of 3 to 4-fold in CTL-P frequency was observed in alloimmune (as compared with normal) C57BL/6 spleen cells. Evidence was obtained suggesting that this increase was specific for the priming alloantigens. A much greater increase in CTL-P frequency (25 to 100-fold) was observed after alloimmunization of C57BL/6 spleen cells in unidirectional MLC. Under the latter conditions, 5 to 20% of the surviving splenic MLC cells could be identified operationally as CTL-P. A similar enrichment in CTL-P frequency was obtained when lymph node, peripheral blood, or thymus cells were cultured for 14 days in MLC. These studies provide direct evidence that the pool of specific CTL-P can be expanded after alloimmunization. Furthermore, the very high frequencies observed after in vitro priming indicate that this system should be particularly useful for future studies of the progeny of individual CTL-P.
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PMID:Limiting dilution analysis of alloantigen-reactive T lymphocytes. III. Effect of priming on precursor frequencies. 15 30

Spleen cells from mice treated with cyclophosphamide (100 to 200 mg/kg) were unable to generate effective cytotoxic thymus-derived cells to allogeneic tumor cells in vitro. The inability of lymphoid cells from cyclophosphamide-treated mice to generate thymus-derived cytotoxic cells became more apparent as the number of responding cells became limited. This depressed response was not due to the elimination of cytotoxic precursor cells since normal response levels were restored by the addition of thymus cells. The added thymus cells did not provide cytotoxic cells in the culture. The thymus cells active in restoring cytotoxic activity were sensitive to mitomycin C, cyclophosphamide, and anti-theta serum and complement. In addition, the active thymus cells were located in the cortisone-resistant pool and did not adhere to nylon wool columns.
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PMID:Restoration of cyclophosphamide-induced suppression of thymus-derived cytotoxic cell generation by normal thymocytes. 15 6

The quantity of C-type RNA tumor viruses in homogenate-sonicates of thymus-bone marrow tissues of C57BL/6J and RFM/Un mice 10 days after irradiation (X-rays or gamma-rays)-plus-urethan treatments is no greater than that in thymus-bone marrow homogenates from nontreated control mice. These results indicate that the leukemogenic activity, shown to be present in such thymus-bone marrow homogenates at this time after irradiation-plus-urethan treatment, is not due to change in quantity of C-type viruses as has been proposed. Virus quantity in tissues was evaluated by a new procedure that includes use of a microchamber with the sides situated on rotor radii so as to produce a uniform virus-containing sediment of tissue homogenate-sonicate that is evaluated by electron microscopic examination of this sections cut perpendicular to the membrane surface. Samples containing as little as 105 to 106 viruses can be relatively easily counted. Semipurified or purified viruses can also be counted after mixing with a tissue homogenate-bovine serum albumin diluent.
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PMID:Evaluation of irradiation-plus-urethan-induced murine leukemia virus "release" using a new method for quantitation of oncornaviruses in tissues. 16 95

Tumor growth and antibody production were evaluated in nude (nu/nu) mice and their heterozygous normal (+/nu) littermates after inoculation of Moloney sarcoma virus (MSV). Sarcoma-bearing nude mice developed progressively growing tumors, whereas 53 percent of their normal counterparts showed tumor regressions. By indirect membrane fluorescence, significant amounts of IgG antibody to MSV could be detected in thymus-bearing but not in nude mice.
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PMID:Moloney sarcoma virus-induced tumors in athymic (nude) mice: growth pattern and antibody responses. 16 70

Tumor-reactive naturally occurring antibodies (NOA) could be readily detected in sera of many mouse strains including congenitally athymic (nude) and germ free (gf) mice. Mice of the CBA/HN strain, however, were found to possess low or undetectable levels of NOA against a wide range of tumor cell lines. Genetic studies indicated that the defect in production of tumor-reactive NOA in CBA/HN mice was largely determined by the absence of an X chromosome-linked gene and is probably similar to the known X chromosome defect of this mouse strain in their antibody response to thymus-independent antigens. In spite of the low level of tumor-reactive NOA, CBA/HN mice do not have a high incidence of spontaneous tumors. These findings suggest that if tumor reactive NOA are involved in immune surveillance against malignancy they are unlikely to act directly in a quantitative manner in the detection and elimination of autochthonous tumors.
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PMID:X chromosome-linked defect of CBA/HN mice in production of tumor-reactive naturally occurring IgM antibodies. 16 60

To study the function of different lymphocyte populations in the Moloney strain of murine sarcoma virus (M-MuSV) tumorigenesis, we gave M-MuSV injections to CBA mice selectively deprived of thymus (T) lymphocytes by thymectomy, X-rradiation, and syngeneic bone marrow injection. Although no tumors appeared in the control group, 80% of the derived mice had tumors that grew progressively and ultimately killed them. In deprived mice, grafted with a syngeneic thymus (reconstituted mice) before or after an M-MuSV injection, tumors regressed or did not develop. Histologically, the lymph nodes and spleens of reconstituted mice, compared to those of deprived animals, showed repopulation of the thymus-dependent areas and prominent follicles in the cortex. Moreover, tumor tissue of reconstituted mice was extensively infiltrated by lymphocytes. To evaluate the number of lymphoid cells needed to prevent or regress M-MuSV tumors, we injected varying amounts of lymphoid cells into deprived mice. Even low lymphocyte numbers (10(6) cells) were sufficient to exert, in some cases, protection against M-MuSV tumorigenesis. This effect was not abolished by subsequent splenectomy or antilymphocyte serum treatment. Finally, deprived mice, given repeated injections of antiserum (hyperimmune) against M-MuSV, had tumors which appeared only after a prolonged latency. From these results, it is concluded that T-cell population integrity is important in affording total host protection against the M-MuSV tumors.
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PMID:Immune reactivity in the Moloney strain of murine sarcoma virus oncogenesis: requirement of thymus-derived lymphocytes for in vivo protection. 17 99

The incidence of regression of wing-web tumors induced by Rous sarcoma virus was shown to be dependent on the quantity of thymus tissue remaining after neonatal thymectomy in chickens of inbred line 6. Frequency of metastasis was associated negatively with the amount of thymus tissue present. Tumor regression and metastasis restriction both appeared dependent on the quantity of thymic tissue present.
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PMID:The influence of thymectomy on Rous sarcoma regression. 17 93

XC cells originally derived from the tumor of a rat previously inoculated with the Prague strain of Rous sarcoma virus were used to induce tumors in chickens surgically thymectomized or bursectomized in the newly hatched period. Thymectomized chickens had a significantly higher incidence of tumors, larger tumors, and a higher tumor mortality, compared with control chickens, when both groups were given 5 X 10(6) XC cells into the wing webs. Bursectomy could significantly influence the tumor size only. It appeared that the capacity of XC cells to induce tumors and the growth of such tumors were subject to immunological influence, with the thymus playing a major and the bursa of Fabricus a minor role under the conditions used.
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PMID:Impaired host defense against XC cell-induced tumors in thymectomized and in bursectomized chickens. 17 28


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