Regulatory mechanism of T cell activation in NOD mice

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The NOD mice have been used as a IDDM model for studying multigenic diseases because at least 16 different loci, named Idd, have been reported. However, their substantial genes are remained unclear except Idd1 linked to MHC class II.Our previous studies suggested that IL-2 gene is a responsible gene in Idd3. This suggestive conclusion is able to be evident by generating congenic mice with NOD phenotypes except IL-2 gene, which should be replaced by MSM IL-2. To produce such a mouse, we planed three steps : 1) Production of IL-2 KO NOD mice by back-crossing of NOD to B6 derived IL-2 KO mice. 2) Introduction of MSM IL-2 gene into T cell lineage of IL-2 KO NOD mice using retrovirus infection system. 3) Back-crossing of IL-2 KO NOD mice with congenic mice, NOD/Shi.Idd3msm/msm. In this academic year, we established a retroviral infectin system for gene introduction into developing thymocytes in a high frequency The ratio of the viral infection or gene integration into T cells has been thought to be very low and difficult but we overcome this problem by following developments. 1) New construction of retroviral vector with rat cDNA for easy detection and enrichment of packaging and infected cells. 2) Coculture of thymocytes with packaging cells instead of virus containing media. 3) Reaggrigation culture of immature thymocytes with packaging cells. In addition to our project, this system we developed is useful for introducing certain genes into developing T cells. We also started to establish IL-2 KO NOD mice and now obtained F2 (IL-2 KO B6 x NOD) x NOD.