Identification of factors sftpporting the survival of mature T lymphocytes

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(1) Establishment of in vitro culture system to support the survival of mature resting T cells and analysis of its mechanism in effective action.We succeeded in establishing the culture of stromal cells derived from lymph nodes of IL-2 receptor β-knock out mice. Using these cells, we analyzed the mechanism how mature resting T cells survive. Lymph nodes-derived stromal cells effectively supported the survival of t cells, and it was suggested that the survival was mediated by some liquid-soluble factors. IL-7 and other cytokines also supported T cell survival but induced proliferation at the same time. In contrast, the most important feature of lymph node-derived stromal cells was that they did not induce proliferation at all, but supported the T cell survival with keeping its resting state.(2) Gene cloning of factors supporting the survival of resting T cells.We cloned the genes of factors that supported T cell survival by screening cDNA from lymph node-derived stromal cells. As a result of screening approximately 100,000 clones with transfection to COS-7 cells and functional assay, 8 cDNA clones were confirmed to have a functional activity to support the T cell survival. Gene sequences of all the 8 clones had alre4ady been registered in the database, but some of them were still functionally unknown.(3) Generation of gene-targeted mice for C-C chemokine 6 and C-C chemokine 9.We started to generate the gene-targeted mice for C-C chemokine 6, which had been cloned in our study, and C-C chemokine 9, the gene of which was located close to C-C chemokine 6, in order to search for their functions in a whole body. The plasmids for the gene targeting of each gene were constructed and are introduced into ES cells.