Downregulation of the NK cell activity on xenograft

α-E/gHLAE的HLA1结构域完全丧失了细胞表面的表达，而α2结构域的表达与HLAG1一样高。α-3和跨膜结构域的替换没有改变。接下来，我们成功地确定了-147位是人类白细胞抗原-E表达的最关键的点。此外，11或66处的点替换导致了细胞表面表达的增强。然而，双取代(11,147)和三取代(11，66,147)对人NK细胞的抑制作用不如对NK细胞的双重取代(11,147)，但对NK细胞的抑制作用不如对人NK细胞的替代147。Delta-SCR2-DAF和Delta-SCR3-DAF不能同时抑制补体介导的和NK介导的PEC裂解。但Delta-SCR4-DAF具有明显的补体调节作用，但对NK细胞无影响。结果表明，DAF通过SCR2-4对NK细胞具有直接的抑制作用。构建了以人类白细胞抗原-G1为跨膜蛋白的FasL基因胞外部分合成的I型膜蛋白。转导FasL-TM的PEC高表达FasL-TM。接下来，作为体外非协调性异种移植的迟发性排斥反应模型，进一步检测了转染物分子对PEC上NK细胞介导的杀伤的改善作用。PIG-α-1，3GT亚克隆了PIG-α-1，3GT基因。并将其导入K562人细胞。随着K562细胞α-Gal表位表达的增加，NK细胞依赖的K562细胞直接裂解作用上调。提示α-Gal表位的NK细胞受体的存在。

HLA-E/GThe substitution of α1 domain of HLA-E completely lost the cell surface expression, however, the α2 domain was expressed very high as same as HLA-G1. The substitution of α3 and transmembrane domain showed no alteration. We next successfully identified position-147 as the most critical point for HLA-E expression. In addition, the point substitution at 11 or 66 led to a enhancement in cell surface expression. However, a dual substitution (11, 147) and a triple substitution (11, 66, 147) are better in expression but not in inhibitory function against human NK cell than the substitution 147.DAF function for NK cellWe report on an investigation of the effect of DAF on NK cell-mediated cytolysis. Delta-SCR2-DAF and delta-SCR3-DAF failed to suppress both complement-mediated and NK-mediated PEC lyses. However, delta-SCR4-DAF showed a clear complement regulatory effect, but had no effect on NK cells. The data suggest DAF has the direct inhibitory function on NK cells via SCR2-4.The Synthesized Type I Membrane Protein of FasLcDNA of the extra cellular portion of the FasL gene with a transmembrane (TM) of HLA-G1 was constructed. The transfectant with FasL-TM was high expressed on PEC.The amelioration of NK cell-mediated lysis by the transfectant molecules on PEC was next tested as an in vitro delayed-type rejection model of a discordant xenograft. The FasL-TM indicated a clear inhibitory effect on NK cell-mediated PEC lysis.pig-α1,3GTThe cDNA of pig-α1,3GT was subcloned. And transfected into K562 human cell. As the K562 transfectants increased the expression of the α-Gal epitope, so the NK cell-dependent direct K562 lysis was up-regulated. The data indicated the existance of the NK cell receptor responsible for the α-Gal epitope.