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- Siesjö, P, et al.
(author)
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Increased proportion of CD8+ tumor responsive T cells after immunization with tum- versus tum+ rat glioma
- 1995
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In: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 165:2, s. 33-225
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Journal article (peer-reviewed)abstract
- Previously established immunogenic (tum-) clones of an ENU (ethyl-N-nitrosourea)-induced rat glioma, N32, were compared to the original tumor concerning their capacity to induce T lymphocyte responses after in vivo immunization and in vitro restimulation of responder spleen cells in mixed lymphocyte tumor culture (MLTC) assays. Quite unexpectedly, original N32 (tum+) in vivo primed spleen cells proliferated to the same extent in vitro in response to tum+ stimulator cells as did tum- in vivo primed spleen cells. However, flow-cytometric analysis of parallel cultures showed a greatly increased proportion of CD3+CD8+ lymphocytes in the proliferating responder cell population from tum- immunized hosts, contrary to a CD3+CD4+ lymphocyte dominance after tum+ immunization. Although the original tum+ N32 tumor cells are not capable of inducing a clearly demonstrable isograft rejection response, they induce a strong T cell response readily detectable in MLTC assays. We propose that the increased CD8+ lymphocyte proliferation could be an essential feature of the isograft rejection response induced by tum- tumor variants. Possible mechanisms of the augmented CD8+ T cell response are discussed.
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- Visse, E, et al.
(author)
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Regression of intracerebral rat glioma isografts by therapeutic subcutaneous immunization with interferon-gamma, interleukin-7, or B7-1-transfected tumor cells
- 1999
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In: Cancer Gene Therapy. - : Springer Science and Business Media LLC. - 0929-1903 .- 1476-5500. ; 6:1, s. 37-44
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Journal article (peer-reviewed)abstract
- Progress in the definition of the roles of various costimulators and cytokines in determining the type and height of immune responses has made it important to explore genetically altered tumor cells expressing such molecules for therapeutic immunizations. We have studied the effect of therapeutic subcutaneous (s.c.) immunizations on the growth of preexisting intracerebral brain tumor isografts in the rat. Transfectant glioma cell clones expressing either rat interferon-gamma (IFN-gamma), rat interleukin-7 (IL-7), or rat B7-1 were selected. After irradiation (80 Gy) the clones were used for immunization (administered in up to four s.c. doses in a hind leg over 14-day intervals starting 1 day after the intracranial isografting of the parental tumor). Significant growth inhibition of the intracerebral parental tumors was induced by transfectants expressing IFN-gamma and IL-7, respectively. The strongest effect was observed with IFN-gamma-expressing cells, resulting in cures in 37% of the males and in 100% of the females. Immunization with IL-7 had a similar, strong initial effect, with significantly prolonged survival in the majority of the rats but a lower final cure rate (survival for >150 days). The B7-1-expressing tumor clones induced cures in seven of eight female rats; however, no cures were seen in the male rats. It was also shown that the B7-1-expressing cells were themselves strongly immunogenic in female rats, requiring high cell numbers to result in a progressively growing tumor upon s.c. isografting; this was not the case in male rats. As a whole, the results imply that despite the unfavorable location of intracerebral tumors, therapeutic s.c. immunizations with certain types of genetically altered tumor cells can induce complete regressions with permanent survival and without gross neurological or other apparent signs of brain damage. The present results demonstrate complete regressions when immunizations are initiated shortly after intracranial isografting, when the intracerebral tumor is small.
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