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Query: UMLS:C0153470 (Spleen)
 4,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spleen necrosis virus (SNV) is an avian retrovirus that can infect some mammalian cells such as dog cells as well as all avian cells tested to date. We were interested in testing whether SNV could also infect primate cells. For these experiments, we used HeLa and COS-7 cells. Initially, we determined whether the SNV long terminal repeat promoter was functional in HeLa and COS-7 cells. In transient transfection assays, the SNV promoter efficiently directed chloramphenicol acetyltransferase gene expression in both HeLa and COS-7 cells. Using SNV- and murine leukemia virus-derived retroviral vectors containing the neomycin phosphotransferase gene, we found that SNV established a provirus in HeLa and COS-7 cells as efficiently as did an amphotropic murine leukemia virus, as judged by the number of G418-resistant HeLa and COS-7 cell colonies obtained after infection and selection. Although SNV formed a provirus in both HeLa and COS-7 cells, productive infection of these cells was not obtained with use of replication-competent SNV. These results suggest that SNV can infect, form a provirus, and stably express a transduced gene in primate cells, but there is a posttranscriptional block to its replication in these cells.
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PMID:Spleen necrosis virus, an avian retrovirus, can infect primate cells. 187 Feb 1

Infection of CMS5 tumor cells with retroviral constructs containing interleukin-2 (IL-2) cDNA and selection in medium supplemented with G418 resulted in the isolation of clones which secreted IL-2. Whereas injection of parental tumor cells resulted in progressive tumor growth, tumor cells secreting high levels of IL-2 were rejected. Furthermore, in animals vaccinated with IL-2-secreting cells, the immunosuppression associated with the inoculation of parental tumor cells did not develop, and these animals resisted a challenge with viable tumor cells. To better understand the functional differences in the anti-tumor responses of immune and tumor-bearing mice which are at the basis for these diverse responses, we used an in vitro model to analyze interactions between splenic lymphocytes and tumor cells. Spleen cells isolated from either tumor-bearing or immune mice proliferated vigorously when cultured alone for 6 days, but much less in the presence of parental tumor cells. This effect could not be transferred with supernatant from tumor cell lines. Spleen cells from tumor-bearing mice remained unresponsive, while those from immune mice proliferated well in response to IL-2-secreting tumor cells. Only spleen cells from immune animals were able to develop cytotoxicity against CMS5 cells following in vitro restimulation. These results are consistent with the interpretation that exposure to parental tumor cells inhibited cell-mediated anti-tumor responses by a mechanism that involved cell-to-cell contact.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vaccination with IL-2-secreting tumor cells stimulates the generation of IL-2-responsive T cells and prevents the development of unresponsiveness. 762 Dec 37