Downregulation of the NK cell activity on xenograft

HLA-E/ gα - 1结构域被取代后完全失去细胞表面表达，而α2结构域与HLA-G1一样表达量很高。α3的取代和跨膜结构域没有变化。接下来，我们成功地确定了位置-147是HLA-E表达的最关键点。此外，在11或66处的点替换导致细胞表面表达增强。然而，双取代（11,147）和三取代（11,66,147）对人NK细胞的抑制作用优于取代147。DAF对NK细胞的作用我们报道了DAF对NK细胞介导的细胞溶解作用的研究。Delta-SCR2-DAF和delta-SCR3-DAF不能抑制补体介导和nk介导的PEC裂解。而delta-SCR4-DAF具有明显的补体调节作用，但对NK细胞无影响。提示DAF通过SCR2-4对NK细胞具有直接抑制作用。构建了FasL基因胞外部分带HLA-G1跨膜（TM）的fasldna合成I型膜蛋白。带FasL-TM的转染物在PEC上高表达。在异种移植物的体外延迟型排斥模型中，通过转染分子改善NK细胞介导的PEC裂解。FasL-TM对NK细胞介导的PEC裂解有明显的抑制作用。猪-α 1,3gt亚克隆猪-α 1,3gt cDNA。并转染到K562人细胞中。由于K562的转染增加了α-Gal表位的表达，因此NK细胞依赖的K562直接裂解被上调。这些数据表明存在负责α-Gal表位的NK细胞受体。

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.