| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥4,200,000 (Direct Cost: ¥4,200,000)
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| Research Abstract |
In the present study, it was indicated that murine LGL with NK activity could be generated from pluripotential hematopoietc stem cells as a result from the extrathymic T-lineage differentiation process. Infection of mice with murine leukemia virus(MLV) induced potent IL 3 production in vivo leading to the splenic hyperplasia, and by culturing the splenic cells in vitro with IL 2, continuous LGL lines could be reproducively established. Based on this original finding, we established IL3/IL2 culture system, in which IL 2-dependant LGL lines could be easily established in vitro by sequential IL3 and IL2 stimulation from normal spleen cells. ALL these lines showed rearranged T-cell recepter(TCR) genes and their expression, and also exhibited typical LGL morphology and NK acitivity. In order to further analyze the mechanism for the generation of LGL, we intended to generate LGL from multipotential hematopoietic progeniter cells in vitro. Using isolated multipotential progenitor colonies induced by IL 3 from % FU-treated mice, it was shown that LGL could be indeed generated directly from such stem cells in vitro in the presence of IL 2 and proper feeder cells. Since such LGL's also showed rearranged and expressed TCR genes as well as typical NK activity, it was definitely proved that the aquisition of NK activity and T-lineage commitment could be induced in vitro by IL 3 and IL 2 from the hematopoietic stem cells in the extrathymic condition. Furthermore, from the developmental analysis, it was revieled that such aquisition of NK activity and TCR gene expression was quite restricted in the embryonal stages, suggesting that the differentiational potential of stem cells into T-lineage cells in the extrathymic environments per se in under the strict developmental regulation. These results certainly clearified the origin and differentiation of LGL/NK, and shoud open new aspects in this field.
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