大鼠移植心脏心肌纤维化的实验研究

目的 分析研究大鼠移植心脏急、慢性排斥反应的心肌纤维化变化。方法 采用供体（Wistar大鼠）脾细胞（CP）预处理移植受体（SD大鼠）,然后行同种异体心脏移植术。对移植心脏的心肌纤维化进行Masson染色分析。结果 急性排斥反应组和环孢素（CsA）组中,移植心脏呈现出严重的心肌纤维化;SPC和CP处理后,移植心脏的存活时间明显延长,其心肌纤维化的程序明显减轻。结论 经供体SPC和CP预处理,可以预防和减缓受体移植心脏心肌纤维化的发生和发展。     

全反式维甲酸减轻大鼠移植心脏血管病变及纤维化

目的 探讨全反式维甲酸(atRA)对大鼠移植心脏血管病变(CAV)及心肌纤维化的影响及可能机制.方法 以近交系Wistar大鼠为供者,SD大鼠为受者,进行异位心脏移植,一组受者术后接受环孢素A(CsA,10 nag·kg-1·d-1)皮下注射,同时以atRA(10 mg·kg-1·d-1)灌胃(atRA治疗组),另一组受者术后接受CsA皮下注射(慢性排斥组).术后60 d,取移植心脏,行Masson染色观察心肌组织纤维化程度,Van Gieson染色分析血管狭窄程度,免疫组织化学染色(sP法)观察心肌组织中CD68+细胞浸润情况,逆转录聚合酶链反应分析心肌组织中血小板生长因子(PDGF)A mRNA的相对含量.结果 慢性排斥组和atRA治疗组心肌纤维化指数分别为64.0±11.9和34.7±6.3,慢性排斥组纤维化指数明显高于atRA治疗组(P<0.01).慢性排斥组的血管狭窄指数为62.9±17.2,atRA治疗组为40.1±8.2,二者比较,差异有统计学意义(P<0.01).慢性排斥组CD68+细胞数为(32.1±9.3)个,atRA治疗组CD68+细胞数为(17.6±4.2)个,慢性排斥组明显高于atRA治疗组(P<0.01).慢性排斥组PDGF-AmRNA的相对含量为0.94±0.11,atRA治疗组为0.46±0.08,慢性排斥组明显高于atRA治疗组(P<0.01).结论 atRA能减轻大鼠心脏移植后的CAV及心肌纤维化,机制可能与其抑制CD68+细胞浸润及PDGF A mRNA表达有关.     

血小板源性生长因子A在大鼠移植心脏血管病变及纤维化中的作用

目的 探讨血小板源性生长因子A(PDGF-A)在移植心脏血管病变及心肌纤维化中的作用.方法 选择近交系健康雄性Wistar大鼠及SD大鼠,建立大鼠异位心脏移植模型.实验分为四组,每组8只.正常对照组:取正常Wistar大鼠的心脏作为空白对照.无排斥组:心脏移植的供、受者均为Wistar大鼠,移植后第60天取移植心脏.急性排斥组和慢性排斥组:心脏移植的供者均为Wistar大鼠,受者均为SD大鼠;急性排斥组术后未行免疫抑制治疗,术后第5天取移植心脏;慢性排斥组术后给予环孢素A 10 mg·kg-1·d-1,皮下注射,移植后第60天取移植心脏.采用免疫组织化学染色法检测移植心脏的巨噬细胞浸润(CD68阳性细胞数)情况;逆转录聚合酶链反应(RT-PCR)分析PDGF-A mRNA的表达水平.结果 正常对照组和无排斥组未见巨噬细胞浸润;急性排斥组巨噬细胞浸润主要见于心肌及冠状血管周围;慢性排斥组巨噬细胞浸润见于心肌及血管周围,在心肌坏死纤维化较严重的区域,巨噬细胞浸润尤为明显;正常对照组、无排斥组、急性排斥组和慢性排斥组移植心组织中PDGF-A mRNA的相对表达量分别为:0.26±0.06、0.31±0.04、0.88±0.12和0.94±0.11,慢性排斥组和急性排斥组中PDGF-A mRNA的相对表达量明显高于正常对照组和无排斥组(P＜0.01).结论 巨噬细胞浸润及血小板源性生长因子表达水平与移植心脏血管病变及心肌纤维化有关.     

急性排斥反应时Fractalkine及其受体在移植心脏中的表达

目的　探讨急性排斥反应过程中Fractalkine(FKN)及其受体CX3CR1在移植心脏局部表达的意义及环孢素A(CsA)对它们的影响。　方法　施行大鼠异位心脏移植术 ,移植大鼠分为 3组 ,每组 45只 ,对照组 5只。SD大鼠间的移植为同系移植组 (A组 ) ,Wistar至SD大鼠的移植分为未用CsA干预组 (B组 )及CsA干预组 (C组 ) ,健康SD大鼠为对照组。采用RT PCR方法检测排斥反应中移植心脏局部FKNmRNA的表达水平 ,免疫组化方法检测FKN和CX3CR1的蛋白表达水平。　结果FKNmRNA与蛋白在A组各时间点和对照组均呈低水平表达 ;在B组的表达变化与急性排斥反应的进程相关 ,术后第 7天FKNmRNA表达上调至峰值 (0 8± 0 2 6) ;C组应用CsA后 ,FKNmRNA表达峰值显著低于B组 (t=2 3 90 ,P <0 0 5 )。FKN和CX3CR1蛋白分别定位于移植心脏血管内皮细胞及间质浸润的单个核细胞中。　结论　急性排斥反应过程中 ,FKN及其受体CX3CR1表达上调 ,与移植物间质单个核细胞浸润密切相关 ;抑制FKN CX3CR1通路的活化可能是CsA发挥作用的又一分子免疫学机制     

大鼠异体肢体移植术后急性排斥反应阶段血管内皮细胞ICAM-1表达的动态变化

目的 研究大鼠异体肢体移植术后急性排斥反应阶段,移植肢体血管内皮细胞细胞间黏附分子-1(intercellular adhesion molecule-1,ICAM-1)动态变化及环孢素A(cyclosporine A,CsA)抗免疫排斥的作用.方法 建立大鼠肢体移植动物模型,随机分为对照组(Wistar大鼠→Wistar大鼠)、排斥组(SD大鼠→ Wistar大鼠)和CsA治疗组(SD大鼠→Wistar大鼠),术后1、4、7 d获取移植肢体股动脉行病理学观察,采用免疫组化法检测移植肢体血管ICAM-1表达的变化.结果 对照组供体移植肢体股动脉血管内皮细胞仅出现轻微肿胀与ICAM-1表达微弱;排斥组血管内皮细胞肿胀明显,淋巴细胞大量浸润,ICAM-1的表达强度和数量明显增加;CsA治疗组移植肢体血管内皮细胞仅有少量淋巴细胞浸润,ICAM-1表达较弱.结论 大鼠异体肢体移植术后急性排斥反应阶段,血管内皮细胞ICAM-1表达水平与排斥反应的发生和发展有关,CsA可降低移植肢体血管内皮细胞ICAM-1表达,抑制复合组织移植术后急性排斥反应.     

环孢菌素A抑制大鼠同种心脏移植急性排斥反应中趋化因子受体CCR5表达的研究

目的观察大鼠同种心脏移植急性排斥反应中趋化因子受体CCID的表达及环孢菌素A（CsA）的抑制作用。方法分两组建立同种大鼠颈部心脏移植模型：对照组（n=25）和新山地明组（CsA组，n=25），各5例观察移植心脏存活时间。于移植术后第1、5、7、14天分别取移植心组织各5例，逆转录-聚合酶链反应（RT—PCR）检测移植心组织内趋化因子受体CCR5mRNA不同时间点的表达水平，免疫组织化学方法检测移植心组织内趋化因子受体CCR5分子的表达差异。结果对照组移植心存活时间为（11．6±1．5）d，CsA组移植心存活时间为（22．4±5．1）d，两组问移植心存活时间差异有统计学意义（P〈0．01）。急性排斥组和CsA处理组大鼠移植心脏在术后第5、7、14天都可检测到趋化因子受体CCR5mRNA阳性表达，但CsA处理组趋化因子受体CCRSmRNA的表达明显弱于急性排斥组。同样急性排斥组和CsA处理组大鼠移植心脏在术后第5、7、14天都可检测到趋化因子受体CCR5分子的表达，CsA处理组趋化因子受体CCR5分子的表达相对较弱。结论趋化因子受体CCR5在早期移植免疫事件中具有重要的作用，CsA能部分抑制趋化因子受体CCR5的表达，并与移植物存活时间延长有一定的关系。     

大鼠异种心脏移植中P选择素和细胞间粘附分子-1表达的意义

目的探讨大鼠异种心脏移植中P选择素和细胞间粘附分子-1(ICAM-1)表达的意义。方法建立金黄地鼠到SD大鼠的异种异位(腹部)心脏移植模型,然后将模型大鼠随机分为4组:对照组术后不采取任何治疗措施;环孢素A组(CsA组)于手术当天起每天腹腔注射CsA10mg/kg;脾切除组于手术当天切除脾脏;CsA联合脾切除组于手术当天切除脾脏,每天腹腔注射CsA10mg/kg。观察每组移植心脏的存活时间,定时和发生排斥反应时切取移植心组织,进行病理学检查,并以免疫组化方法观察移植物中P选择素和ICAM-1的表达。结果CsA联合脾切除组移植心脏存活时间为(34.2±8.98)d,较对照组、CsA组和脾切除组明显延长(P<0.05)。CsA联合脾切除组术后1~5d移植物中未见明显病理改变;7、14d时移植心脏组织结构清晰,未见血栓及出血;30d时移植心脏组织结构基本正常,排斥反应级别为Ⅰ~Ⅱ;其它三组的病理改变明显,对照组于术后1~2d、脾切除组及CsA组于术后4~7d发生延迟性排斥反应。CsA联合脾切除组术后各观察时点移植心脏组织中均未见P选择素和ICAM-1表达,其它三组的P选择素和ICAM-1均呈阳性。结论异种移植发生延迟性排斥反应时,P选择素和ICAM-1均有表达,可以作为判断异种移植免疫抑制治疗效果的指标之一。     

细胞因子在心脏移植急性排斥反应中的表达及其作用机理

目的观察同种大鼠心脏移植急性排斥反应中,局部细胞因子网络的变化及其机理.方法健康雄性Wistar大鼠(受体)和SD大鼠各48只,将接受移植心脏的Wistar大鼠分4组,每组12只.A组对照组;B组抗白介素2单克隆抗体(IL-2Mab)组;C组环孢菌素A(CsA)组;D组IL-2Mab加CsA组.4组大鼠分别静脉给予生理盐水、抗白介素2单克隆抗体及口服CsA、静脉给予抗白介素2单克隆抗体加口服CsA,采用改良的移植术式建立移植模型.常规监测排斥反应发生情况.应用RT-PCR的方法于术后第1、3、5、7、9、11、14天动态检测移植物局部细胞因子IL-1β、IL-2、CD25、IL-4、IL-5、IL-6、IL-10、TNFα、IFNγ的表达水平.结果移植心脏存活时间,A组为(8.3±1.7)d;B组为(29.2±7.1)d;C组为(26.4±5.7)d;D组为(55.0±11.6)d.B、C、D组移植心脏存活时间显著延长,与A组相比,差异有极显著性意义(P＜0.01).存活时间较长的移植心脏的淋巴细胞浸润和心肌坏死的程度比存活时间较短的心脏明显减轻.IL-1β的表达在各组均较高;IL-4、IL-5、IL-6、IL-10的表达水平在移植心脏存活时间较长的组较高;而IL-2、CD25、IFN-γ、TNFα的表达则相对较低;4组相比差异有显著性意义(P＜0.05).结论细胞因子网络在心脏移植排斥反应中发生了相应的变化,并与干预的因素及移植物存活时间有密切的关系.IL-2Mab、CsA联合用药促使TH1类细胞因子向TH2类细胞因子整体偏离,这种免疫偏离使移植心脏存活时间显著延长.     

急性排斥反应过程中淋巴细胞趋化因子基因表达的意义

目的　探讨急性排斥反应过程中淋巴细胞趋化因子 (LTN)mRNA在移植心脏局部表达的意义及环孢素A(CsA)对其的影响。方法　以SD大鼠为受者 ,Wistar大鼠为供者 ,施行异位 (腹腔 )心脏移植术 ,分为术后使用CsA组 (15mg·kg-1·d-1)和不用组 ,并设SD大鼠间的心脏移植组 (同系移植组 ) ,以正常SD大鼠为对照组。采用一步法逆转录 聚合酶链反应 (RT PCR)检测术后不同时间移植心脏局部LTNmRNA的表达。结果　正常对照组和同系移植组在各时间点均未见LTNmRNA表达 ;LTNmRNA在未用CsA组的表达变化与急性排斥反应的进程相关 ,排斥反应的早期出现LTNmRNA表达上调 ,术后 5d时达到峰值 ,而应用CsA组 ,LTNmRNA的表达峰值出现延缓 ,且明显低于未用CsA组 (P <0 .0 5 )。结论　LTNmRNA的表达上调与排斥反应过程中淋巴细胞浸润密切相关 ,可能对急性排斥反应的早期诊断有帮助 ;CsA可抑制LTN基因的表达 ,可能是其免疫抑制作用的又一分子免疫学机制     

缺血对移植心脏冠状血管的影响

目的 探讨缺血对移植心脏远期冠状血管的形态学影响。方法 雄性Wistar大鼠为供者和受者，建立大鼠腹部异位心脏移植模型。实验分为4组，即假手术对照组、立即移植组、供心缺血3h移植组和缺血6h移植组。每组术后均用环孢素A(CsA)灌胃20d，抗排斥反应。20d时，取出供心，观察心脏冠状血管病理改变及超微结构变化。结果 假手术对照组心脏和立即移植组的供心冠状血管内皮超微结构均无明显损害；随着供心缺血时间的延长，移植后冠脉小血管内皮细胞肿胀，冠状动脉的内皮细胞增生，内膜增厚；缺血6h移植组供心冠状血管内膜超微结构改变非常明显。结论 供心缺血可导致移植后冠状血管内皮损伤，是心脏移植术后冠状血管病理改变的重要因素。     

Increased expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in rat cardiac allografts

This study was designed to investigate the role of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) during chronic cardiac allograft rejection. Wistar rats were used as donors, and SD rats as recipients heterotopic cardiac transplants. Recipients pretreated with inoculation of donor splenocytes (SPC) followed by cyclophosphamide (CP) were divided into 4 groups: (A) untreated group (n = 18) without immunosuppression; (B) SPC plus CP-treated group (n = 18) that were euthanized at 15-120 days posttransplantation; (C) CsA-treated group (n = 18) euthanized at 2-3 months posttransplantation; and (D) tolerance group (n = 18) treated with SPC plus CP and monitored for at least 1 year posttransplantation. Cardiac allografts were harvested at various times for immunohistochemical studies performed to evaluate the expression of ICAM-1 and VCAM-1. Pretreatment of animals with SPC and CP induced long-term cardiac allograft survival. Immunohistochemical staining demonstrated a low level of ICAM-1 and VCAM-1 expression in cardiac allograft muscle and coronary arteries among Groups B and D. In contrast, the expressions of ICAM-1 and VCAM-1 in cardiac allografts of Groups A and C were significantly higher than those in Groups B and D. Our results suggested that the expression of ICAM-1 and VCAM-1 plays an important role during the development of chronic cardiac allograft rejection.     

The effects of platelet-derived growth factor in rat cardiac allograft vasculopathy and fibrosis

We investigated the relationship between expression of platelet-derived growth factor (PDGF) and development of chronic rejection. Rat recipients pretreated by inoculation of donor splenocytes (SPC) followed by cyclophosphamide (CP) were divided into three groups: control animals without immunosuppression (group 1, n = 10); group 2 recipients treated with cyclosporine (n = 10), and euthanized at 2 to 3 months posttransplantation; group 3 (n = 20) animals treated with SPC and CP with 10 recipients euthanized at 2 weeks posttransplantation and 10 monitored for at least 1 year. Immunohistological and pathological studies were performed to evaluate cardiac allograft vasculopathy (CAV), myofibrosis, and expression of PDGF. Allografts collected from group 2 demonstrated abundant infiltration of collagenous fibers in the coronary arteries. Edema and proliferation of the intima as well as the lumial stenosis were revealed in groups 1 and 2. Additionally, immunohistological staining demonstrated a high expression of PDGF protein in cardiac muscles and coronary arteries in groups 1 and 2. In contrast, pretreatment of animals with SPC plus CP induced long-term allograft survival. Importantly, the expression of PDGF in cardiac muscles and arteries in group 3 was significantly less than groups 1 and 2. CAV were dramatically reduced in group 3 when compared with groups 1 and 2. Preconditioning of recipients with SPC and CP suppressed the expression of PDGF within allografts and induced transplant tolerance. Our results suggested that the expression of PDGF plays an important role during the development of cardiac allograft rejection.     

抑制趋化因子受体CCR5减轻小鼠同种异体移植心脏急性排斥反应的研究

目的 研究抑制趋化因子受体CCR5减轻小鼠同种异体移植心脏急性排斥反应的作用机制.方法 采用小鼠颈部心脏移植模型,将96只小鼠用随机数字表法分为4组,每组24只,供、受者各12只,A组术后给予anti-CCR5 mAb和CsA,B组术后给予anti-CCR5 mAb,C组术后给予CsA,D组为对照组,术后给予生理盐水.于术后第7d取各组移植心组织6例,检测CCR5及IL-2和IL-10的表达差异,其余6例用于观察移植心脏存活时间.结果 A、B、C组小鼠移植心脏存活时间明显延长,其CCR5及IL-2的表达较D组明显减少,IL-10的表达明显增加.结论 抑制趋化因子受体CCR5对同种异体移植心脏有明显的保护作用,可能与细胞因子的表达有关.     

Combined vascular endothelial growth factor and platelet-derived growth factor inhibition in rat cardiac allografts: beneficial effects on inflammation and smooth muscle cell proliferation

BACKGROUND: Perivascular inflammation and subsequent smooth muscle cell (SMC) proliferation are central in the development of cardiac allograft arteriosclerosis. We examined the effect of combined inhibition of proinflammatory vascular endothelial growth factor (VEGF) and SMC mitogen platelet-derived growth factor (PDGF) in rat cardiac allografts. METHODS: Heterotopic cardiac transplantations were performed between fully major histocompatibility mismatched rat strains receiving cyclosporine A immunosuppression. In situ hybridization and immunohistochemistry were performed to examine VEGF and PDGF ligand and receptor (R) expression. Protein tyrosine kinase inhibitors PTK787 and imatinib were used to inhibit VEGFR and PDGFR activity, respectively. Rat coronary artery SMC migration and proliferation assays were used to examine the effect of VEGF and PDGF and tyrosine kinase inhibitors in vitro. RESULTS: Both ligand and receptor expression of VEGF and PDGF were detected in chronically rejecting allografts. In vitro, PDGF-BB mediated rat coronary artery SMC migration and proliferation was completely inhibited with imatinib and partially with PTK787. In vivo, combined treatment with PTK787 and imatinib significantly reduced the formation of neointimal lesions in arteries of cardiac allografts at 8 weeks, producing a greater effect than either drug alone. PTK787, in contrast with imatinib, reduced the number of ED1 macrophages and PDGF-B immunoreactivity in the allografts at 4 weeks. CONCLUSIONS: Blocking VEGF and PDGF receptor signaling in cardiac allografts has distinctive effects on inflammation and SMC proliferation, suggesting that targeting both inflammation and pathologic vascular remodeling may be needed to inhibit cardiac allograft arteriosclerosis.     

移植心脏动脉硬化和心肌细胞坏死的研究

目的 探讨心肌细胞坏死、纤维化和动脉硬化在移植心脏中的发生和发展情况,为心脏移植的抗排斥反应治疗和预防提供依据。方法 用供体脾细胞（ＳＰＣ）和环磷酰胺（ＣＰ）预处理移植受体,然后行异位心脏移植术,ＨＥ、Ｍａｓｓｏｎ、Ｖａｎ、Ｇｉｅｓｏｎ染色对移植以及瓣炎细胞浸润、心肌细胞坏死、心肌纤维化的冠状动脉硬化进行分析。结果 ＳＰＣ和ＣＰ预处理后,移植心脏的存活时间明显延长,炎细胞浸、心肌细胞坏死、心肌纤维     

Differentiated expression patterns of growth factors in routine formalin-fixed endomyocardial biopsies in the early postoperative phase after heart transplantation

BACKGROUND: Platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) seem to play a key role in immunological reactions shortly after heart transplantation (HTx). The aim of this study was to analyze the time course of the expression of PDGF A and B, PDGF-receptor alpha (PDGF-Ralpha) and beta, aFGF, and bFGF on formalin-fixed routine endomyocardial biopsies. PATIENTS AND METHODS: Right ventricular endomyocardial biopsies were obtained from 36 heart transplant recipients up to 2 weeks after HTx. According to the clinical course in the first postoperative year, 3 groups were formed: (1) clinically uneventful course (n = 12); (2) cardiac/systemic infections (n = 12); (3) acute rejection (n = 12). The growth factor expression was examined immunohistochemically. RESULTS: In the early phase after HTx, PDGF A, PDGF B, PDGF-Ralpha, and PDGF-Rbeta were predominantly expressed in endothelial cells. The main expression of PDGF-Ralpha and bFGF was found in cardiomyocytes, endothelial cells, and smooth muscle cells. During the first 2 postoperative weeks, PDGF A, PDGF B, and PDGF-Rbeta showed a similar time course of expression: A significantly elevated expression in the first week was followed by a decrease in the second week. In the rejection group, PDGF A was significantly elevated after the first week. CONCLUSIONS: The increased expression of PDGF in the first postoperative week can be interpreted as an unspecific reaction to peritransplant injury. The prolonged expression of PDGF A, PDGF B, and PDGF-Rbeta showed that there were ongoing immunological reactions in the transplant during week 2. The persistence of elevated PDGF A expression might be of prognostic value in terms of a risk factor for either infection or rejection.     

The effect of acute rejection and cyclosporin A-treatment on induction of platelet-derived growth factor and its receptors during the development of chronic rat renal allograft rejection

BACKGROUND: In the development of chronic kidney allograft rejection acute rejection (AR) is the single most important risk factor. Although Cyclosporin A (CsA) medication has decreased the incidence of AR, chronic rejection (CR) is still the major reason for late allograft loss. Platelet-derived growth factor (PDGF) is a major mitogen mediating mesenchymal cell proliferation in CR. We have investigated the impact of AR and different doses of CsA on the expression of PDGF ligands and receptors in the development of CR. METHODS: Kidney transplantations were performed from DA to WF rats and syngenic controls were done from DA to DA rats. Two groups of allografts were treated daily with CsA either at low dose (1.5 mg/kg) or high dose (5 mg/kg). Third group of allografts was treated with CsA 5 mg/kg/day for 1 week and then left untreated until the development of AR. AR episodes were treated with CsA 5 mg/kg/day. Grafts were harvested 3 months after transplantation for histology and immunohistochemistry (PDGF-AA, -BB and PDGFR-alpha, -beta). RESULTS: In syngenic grafts no histological signs of CR were seen and the expression of PDGF ligands and receptors remained almost nonexistent. AR episodes increased the chronic rejection changes. High-dose CsA-treatment ameliorated inflammation compared to low-dose CsA-treatment, although it failed to inhibit the development of chronic changes. More fibrosis was even seen in high-dose than in low-dose CsA-treated grafts. CR in each allograft group was associated with induction of all PDGF ligands and receptors (P<0.05 compared with syngenic controls) in interstitial inflammatory cells, capillary endothelium, and arterial smooth muscle cells. In the group with AR episodes the expression was further increased. CONCLUSIONS: Our results demonstrate that CsA treatment cannot inhibit the expression of PDGF ligands and receptors in the development of chronic kidney allograft rejection and that AR episodes induce even more PDGF and its receptors in the graft indicating a link between AR and subsequent development of CR.     

Evidence for Cooperativity in the Rejection of Cardiac Grafts Mediated by CD4+ TCR Tg T Cells Specific for a Defined Allopeptide

Understanding the mechanisms of rejection of organs transplanted between unrelated individuals is confounded by the complexity of the alloantigens and the diversity of T cells responding to these alloantigens. To circumvent these problems, we developed a transgenic (Tg) C57BL/6 model system in which the T-cell receptor (TCR) expressed by CD4 T cells is specific for a defined allogeneic H-2Kd peptide and the cardiac donor expressed H-2Kd as a transgene on the C57BL/6 background (B6.Kd). These TCR Tg T cells were previously shown to mediate rapid rejection of a B10.D2 cardiac allograft when transferred to Rag1 recipients, demonstrating that the "indirect" pathway of allorecognition is sufficient for complete rejection in the absence of other T cells or antibody. Here, we report that B6.Kd hearts were rejected in an accelerated fashion by Rag1(-/-) TCR Tg T cells adoptively transferred to normal B6 recipients. Rejection in this model was associated with large myocardial infarcts and significant coronary artery inflammation. Moreover, transferred TCR Tg CD4+ cells mediated allograft injury without the requirement for cytotoxic function from recipient-derived CD8 T cells. A non-linear relationship was observed between the initial precursor frequency of the antigen-specific TCR Tg cells and the ultimate tempo of acute rejection, which is taken as evidence for cooperativity between components of the system.     

Prolonged Cardiac Allograft Survival in Mouse Model After Complement Depletion with Yunnan Cobra Venom Factor

Background

Activation of the complement system is the leading mechanism that causes antibody-mediated acute rejection and hyperacute rejection after xenotransplantation. The major cause of acute rejection in allogeneic transplantation is the T cell–mediated specific immune response. We studied the effects of complement on acute rejection after cardiac allotransplantation using complement depletion with cobra venom factor (CVF) in the mouse.

Materials and Methods

The Balb/c-C57 mouse model of heterotopic cardiac allograft was used. The mice were divided into 2 groups, a control group and a CVF-treated group. After intravenous injection of CVF, the experimental group was observed for allograft survival time. Twelve mice from the control and experimental groups were sacrificed on days 3, 5, and 7 after the operation. The pathologic grade of acute rejection, deposition of C3 in tissue, extent of infiltration by CD4+ and CD8+ T cells, and expression of MHC-II, B7-1, and B7-2 were compared between the 2 groups.

Results

In the CVF-treated group, mean (SD) survival of the cardiac allograft was 26.2 (1.7) days, and in the control group was 8.4 (0.4) days (P < .01). Pathologic examination and immunohistochemistry demonstrated that the grade of acute rejection, deposition of C3 in tissue, extent of infiltration of CD4+ and CD8+ T cells, and expression of MHC-II, B7-1, and B7-2 were significantly decreased in the CVF-treated group.

Conclusion

Depletion of complement in the serum with CVF inhibits acute cardiac allograft rejection in the mouse.