异种移植超急性排斥机理的实验研究

Experimental study of the mechanism of xenograft hyperacute rejection in swine to human combination

为了研究补体经典和旁路途径在超急性排斥中的作用，选择猪血管内皮细胞为靶，人血清为天然抗体和补体源，用四唑盐法（MTT）行补体依赖的细胞毒反应（CDC）。人血清能溶解（58±5）％的猪血管内皮细胞；加入乙二醇四乙酸阻断经典途径后人血清的溶细胞率降为（51±3）％（P＜0．01）；入血清50℃加热20分钟，阻断旁路途径后，其落细胞率降为（42±5）％（P＜0．01）；将经典途径和旁路途径分别被阻断的人血清混合，血清的细胞毒作用恢复正常。在这一体外超急性排斥模型中，补体经典和旁路两条途径均参与超急性排斥。提示抑制猪-人之间的超急性排斥应考虑补体旁路途径激活的问题。

Complement activation is central to the rejection of discordant xenograft. In order to assess the respective roles of direct and alternative pathways, an in vitro model of hyperacute rejection in the swine-to-human donor-recipient combination was designed, using a complementdependent cytutoxicity test with human serum as the source of xenogenic antibodies and complement. The cytotoxic activity of xenogenic was evaluated by a colorimetric assay using MTT. Pure human serum lysed (58±5) % of swine endothelial cells. Selectlve inhihition of the direct pathway by adding EGTA to the serum reduced cytolysis to (5±3) % (P＜0.01 versus normal serum ).When alternative pathway was selectively inhlbIted by heating for 20 mlnutes at 50℃, the lytic activity of human serum dropped to (42±5) % (P＜0.01 versus normal serum). Mixing serum with deficient direct pathway and serum with deficient alternatlve pathway restored the cytotoxiclty to normal levels. In this model of in vitro hyperacute rejection, both pathways of complement activatlon are lnvolved, suggesting that regimens designed to inhibit hyperacute rejection of swine xenograft into human should take the alternative pathway activation of complement into account.