| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1990: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1989: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Limiting Dilution Analysis (LDA) is a quantitative method with a high degree of accuracy and an indispensable way for the elucidation of rejection mechanism and tolerance. It is possible to estimate the absolute clonal size of Tcp (T cytotoxic precursor) by calculating the frequency of Tcp[ f (Tcp)]
. The experimental model is a heterotopic heart transplantation in rats. Buffalo (BUF : RT-1^b) rats were used as heart donors and Wistar-Furth (WFu : RT-1^u) rats as recipients. The spleen T cells of untreated rats had a f (Tcp) of 1:2343<plus-minus>591, but the f (Tcp) just before rejecti on increased up to 1/195<plus-minus>123 which was about 12 times as high as that of the untreated rats. However, the allografted WFu rats had a decreased f (Tcp) of 1 : 696<plus-minus>243 after graft rejection.
Thus, the present study concentrated upon the f (Tcp) of graft infiltrating cells (GICs) on day 5 postgrafting during ongoing rejection. The GICs in an allograft showed a remarkably high f (Tcp) of
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1 : 113 in comparison with a f (Tcp) of 1 : 8584 seen in an isograft. The number of GICs obtained from allografts was (2.1<plus-minus>1.1)x10^7/graft. This was ten times as many as that isolated from isografts. The FACS analysis of GICs-T revealed that the number of percentage in OX19^+ (T), OX8^+ (Tc/s) and W3/25^+ (Th) cells were 70.9%, 64.5% and 25.9%. respectively.
On day 5 postgrafting, the f (Tcp)s of spleen and lymphnode T cells were 1 : 195<plus-minus>123, 1:731<plus-minus>81, respectively. However, the GICs had the highest f (Tcp) of 1:84<plus-minus>53. Therefore, about 1.2% (1/84) of GICs-T cells was the donor specific Tcp on day5 postgrafting during ongoing reje
On the other hand, the GICs also had T cells which could suppress the proliferative response of Mixed Lymphocyte Culture (MLC) in a donor specific manner. We could make some clones from the GICs on day 5 transplantation. The surface markers of these clones were Ox19^+ (T), W3/25^+ (Th),OX8^- (Ts/c), and OX22^+ (LCA). These clones could suppress the MLC response in a donor specific manner.
Therefore, it is suggested that there might be a regulation mechanism by the T cells which could suppress the unlimited proliferation of donor antigen specific Tc cells in the graft during ongoing rejection on day 5 postgrafting. Less
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