摘要目的利用小鼠→大鼠心脏移植模型，探讨延迟性异种移植排斥反应(DXR)的病理特征及IgG的作用。方法将移植大鼠随机分成4组：对照组(A组，n＝6)；环孢素A(CsA)组(B组，n＝6)，CsA 每2日用药1次，每次20 mg/kg，自移植当日(day 0)起使用；环磷酰胺(CyP)组(C组，n＝6)，移植前1 d给予CyP 40 mg/kg，自移植后第1天起每2日用药1次，每次20 mg/kg；CsA加CyP 组(D组，n=5)。血清IgG水平用ELISA法测定；C3、IgG和CD68用免疫组织化学法检测。结果发生DXR时移植心脏表现为血管内血栓形成，大量巨噬细胞浸润及心肌凝固性坏死，无补体C3沉积。单用CsA或CyP不能显著延长移植到大鼠的小鼠心脏存活时间,亦不能显著降低受体血清IgG水平。联合应用CsA和CyP可使移植心脏存活(4.80±1.48)d,与A组比较差异有显著性意义(P＜0.05)；且使DXR时受体血清IgG水平降低，差异有显著性意义(P＜0.05)；移植物中IgG沉积在4组间差异无显著性意义(P＞0.05)。结论 DXR时移植物中有大量巨噬细胞浸润和IgG沉积。CsA和CyP联合应用可抑制受体血清IgG水平升高，延长移植到大鼠的小鼠心脏存活时间，但不能防止DXR的发生。

abstractsObjective　To study the characteristics pathological and the role of IgG in delayed xenograft rejection (DXR) in mouse-to-rat heart transplantation model.　Methods　The animals were divided in to 4 groups: group A (n=6), controls received no immunosuppression; group B (n=6), treated with cyclosporine (CsA)20 mg/kg every other day from day 0; group C (n=6), added cyclophosphamide (CyP) 40 mg/kg at the day before operation, and then 20 mg/kg, every other day from the day after operation; group D (n=5),combined CsA with CyP. Serum IgG was detected by enzyme linked immunosorbent assay (ELISA). C3, IgG and CD68 were determined by immunohistochemistry.　Results　The pathology of rejected xenografts showed wide-spread intravascular thrombosis, associated with a large number of infiltrated macrophages and coagulative necrosis. Adminstration of CsA or CyP alone had no significant effect on xenograft survival. However, combination of CsA with CyP significantly prolonged the xenograft survival to (4.8±1.48)*!d (P＜0.05 vs group A), and significantly decreased the serum IgG levels (P＜0.05), but it had no effect to decrease IgG deposition (P＞0.05).　Conclusions　Macrophages and increased IgG play an important role during DXR in the mouse-to-rat heart transplantation model. Combination of CsA with CyP decreases the serum IgG levels in the xenografts and effectively prolongs the xenograft survival.