Davis E A, Lam T T, Qian Z, Ibrahim S, Baldwin W M, Sanfilippo F P
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md, USA.
J Heart Lung Transplant. 1995 Sep-Oct;14(5):973-80.
Hyperacute xenograft rejection is affected by activation of the complement cascade. Split products of early complement components influence the localization, activation, and effector function of platelets, granulocytes, and lymphocytes, whereas the formation of the membrane attack complex (C5b-9) leads to direct cellular injury. In a unique strain of PVG rats deficient in the C6 component of complement, the terminal membrane attack complex is not formed. However, production of the chemotactic and vasoactive components C3a and C5a proceeds normally. Guinea pig cardiac xenografts in these C6-deficient rats have prolonged survival, and at the time of rejection the inflammatory infiltrate is composed primarily of neutrophils. NPC 15669, a member of a class of antiinflammatory agents called leumedins, is known to inhibit neutrophil adhesion. The purpose of this study was to determine whether inhibition of neutrophil recruitment in animals incapable of membrane attack complex formation would prolong cardiac xenograft survival.
Cardiac xenografts from male Hartley guinea pigs were heterotopically grafted into PVG (C-) and PVG (C+) male rats. Experimental animals received 20 mg/kg of NPC 15669 i.v. before cross-clamp release and 10 mg/kg of NPC 15669 intravenously on postoperative day 1. Control animals received intravenous saline solution only.
Complement sufficient PVG (C+) rats rejected cardiac xenografts hyperacutely despite mode of treatment: PVG (C+) rats which received saline solution (n = 5) rejected their xenografts at 10.8 +/- 2.6 minutes, and those receiving NPC 15669 (n = 5) rejected at 13.9 +/- 5.3 minutes. Histologic examination showed edema, platelet aggregation, and hemorrhage but no cellular inflammatory infiltrate. As expected, complement-deficient PVG (C-) rats had markedly longer xenograft survival in the saline solution-treated group (n = 5) with graft function being sustained 14.7 +/- 6.1 hours. NPC 15669 treatment (n = 4) further prolonged graft function to 61.0 +/- 4.7 hours. In addition to edema, platelet aggregation, and hemorrhage, histologic analysis of these grafts at the time of rejection was characterized by an infiltration of neutrophils.
We conclude that neutrophils play a critical role in cardiac xenograft rejection when complement activation is restricted. Combined inhibition of complement and neutrophil adhesion prolongs xenograft survival longer than inhibition of either component alone.
超急性异种移植排斥反应受补体级联激活的影响。早期补体成分的裂解产物影响血小板、粒细胞和淋巴细胞的定位、激活及效应功能，而膜攻击复合物（C5b-9）的形成会导致直接的细胞损伤。在一种独特的PVG大鼠品系中，其补体C6成分缺陷，不会形成终末膜攻击复合物。然而，趋化性和血管活性成分C3a和C5a的产生正常进行。在这些C6缺陷大鼠中移植的豚鼠心脏异种移植物存活时间延长，且在排斥时炎症浸润主要由中性粒细胞组成。NPC 15669是一类名为亮肉菌素的抗炎剂中的一员，已知其能抑制中性粒细胞黏附。本研究的目的是确定在无法形成膜攻击复合物的动物中抑制中性粒细胞募集是否会延长心脏异种移植物的存活时间。
将雄性Hartley豚鼠的心脏异种移植物异位移植到雄性PVG（C-）和PVG（C+）大鼠体内。实验动物在松开交叉钳夹前静脉注射20mg/kg的NPC 15669，并在术后第1天静脉注射10mg/kg的NPC 15669。对照动物仅接受静脉生理盐水溶液。
无论治疗方式如何，补体充足的PVG（C+）大鼠均超急性排斥心脏异种移植物：接受生理盐水溶液的PVG（C+）大鼠（n = 5）在10.8±2.6分钟时排斥其异种移植物，而接受NPC 15669的大鼠（n = 5）在13.9±5.3分钟时排斥。组织学检查显示有水肿、血小板聚集和出血，但无细胞炎症浸润。正如预期的那样，补体缺陷的PVG（C-）大鼠在生理盐水处理组（n = 5）中的异种移植物存活时间明显更长，移植功能维持14.7±6.1小时。NPC 15669治疗组（n = 4）进一步将移植功能延长至61.0±4.7小时。除水肿、血小板聚集和出血外，这些移植物在排斥时的组织学分析特征为有中性粒细胞浸润。
我们得出结论，当补体激活受到限制时，中性粒细胞在心脏异种移植排斥中起关键作用。联合抑制补体和中性粒细胞黏附比单独抑制任何一种成分更能延长异种移植物的存活时间。
