| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥5,800,000 (Direct Cost: ¥5,800,000)
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| Research Abstract |
Rabbit and mouse thymuses were found to have tissue-characteristic glycosphingolipid composition, when compared with those of the other tissues and the glycosphingolipids were distributed in the cortex region of the thymus. Since the glycosphingolipids were not detected in the bone marrow even in a trace amount, they were thought to be newly synthesized after the bone marrow cells reached to the thymus. The tissue-characteristic glycosphingolipids in rabbit and mouse thymuses were IV^3NeuGcnLc_4Cer and VI^3NeuGcnLc_6Cer, and IV^3NAGg_5Cer and IV^3NAGg@>D26@>D2Cer, respectively.
Neuraminidase treatment of rabbit and mouse thymocytes caused the modification of the cell surface antigenecity by cleaving the sialic acid to give more than 5 times increase of nLc_6Cer and Gg_6Cer. And the interleukin 2-production of the thymocytes by interaction with B-cells and macrophages was only observed on the neuraminidase-treated thymocytes, but not on the native thymocytes. In addition, B-cells- and ma
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crophage-dependent interleukin 2-production of neuraminidase-treated rabbit and mouse thymocytes was inhibited with nLc_6Cer- or Gg_6Cer-containing liposomes, respectively, indicating that nLc_6Cer and Gg_6Cer were the receptors for B cells and macrophages.
On the other hand, when corticosteroid was intraperitoneally injected to rabbit and mouse,the tissue-characteristic gangliosides of the steroid sensitive thymocytes in the cortex were selectively disappeared from the thymus. Howerer, a significant increase of GM3 ganglioside in the thymus matrix cells was observed at the same time. This might be related to the efflux of the thymocytes from the tissue by detachment of the cells from the thymus matrix cells. When determined the GM3 metabolism with ManNAc or CMP-NeuAc as the substrates, the synthetic capacity of GM3 from CMP-NeuAc was only observed in the thymus 48 hours after steroid administration, indicating that a plasma-membrane-associated sialyltransferase is induced in the thymus matrix cells. Less
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