CTLA4-Ig和抗CD40L单克隆抗体抑制大鼠胰腺移植急性排斥反应的机制

目的探讨细胞毒T淋巴细胞相关抗原4免疫球蛋白（CTLA4-Ig）和抗CD40L单克隆抗体对异基因大鼠胰腺移植后急性排斥反应的作用及其相关机制。方法建立大鼠的胰十二指肠移植模型，供者为F344大鼠，受者为经链尿佐菌素诱导为糖尿病模型的Lewis大鼠，受者移植后分为4组，每组12只。A组：为应用生理盐水对照组；B组：应用CTLA4-Ig200μg；C组：应用抗CD40L单克隆抗体200μg；D组：联合应用CTLA4-Ig和抗CD40L单克隆抗体各200μg。各组分别于术后第2d腹腔注射相应的药物。术后1、4、7、10d分别取各组的移植胰腺，进行常规病理检测；采用逆转录聚合酶链（RT-PCR）法检测移植物白细胞介素2（IL-2）、白细胞介素4（IL-4）、白细胞介素10（IL-10）、γ干扰素（IFN-γ）的表达；术后第1、4、7、10d取受者外周血，采用流式细胞术计数T细胞亚群CD3^＋、CD4^＋和CD8^＋；术后第4d取移植胰计数CD4^＋CD25^＋T细胞。结果病理检测显示：与A组相比，B、C组排斥反应明显减弱，D组几乎未发生排斥反应；B、C、D组IL-2的表达高峰延迟，且表达水平较A组有不同程度的降低，D组又较B、C组表达水平下降，差异有统计学意义；B、C、D组IFN-γ的表达水平较A组有不同程度的降低，但D组与B、C组的差异不显著；B、C组IL-4的表达水平较A组有不同程度的升高，D组较A、B、C组表达水平下降，差异有统计学意义；B、C组IL-10的表达水平较A组有不同程度的升高，D组与A组差异不显著；B、C、D组CD3^＋、CD4^＋和CD8^＋T细胞数均相对减少，CD4^＋CD25^＋T细胞数有不同程度升高，与A组比较，D组的差异最为显著。结论联合应用CTLA4-Ig和抗CD40L单克隆抗体能更有效地抑制大鼠胰腺移植后排斥反应，其机制可能与Th1／Th2型细胞因子偏移及CD4^＋CD25^＋调节性T细胞增多等有关。     

联合阻断CD28/B7与CD40/CD40L共刺激通路诱导抗原特异性免疫耐受

目的探讨阻断CD28／B7与CD40／CD40L共刺激通路对同种异体小鼠移植心脏存活时间的影响及其机理。方法实验分4组进行，均以C57BL／6小鼠为受者，BALB／c小鼠为供者，施行腹部异位心脏移植，根据分组要求，MR1组于移植当天静脉内注射抗CD40L单克隆抗体（MR1抗体）0．25mg／d，移植后第2、4天改为腹腔注射0．25mg／d；抗B7组于移植当天至术后第4天腹腔内注射抗B7—1和抗B7—2抗体各0．1nag／d；联合处理组术后联合使用MR1抗体和抗B7抗体，二者的用法同MR1组和抗B7组；对照组术后不使用任何抗体。记录各组移植心的存活时间；移植后60d时对移植心脏组织行病理学检查。联合处理组的受者于心脏移植后150d分别接受供者来源（BALWc小鼠）及无关供者来源（C3H小鼠）的皮肤移植，对照组的受者也同时接受两种皮肤移植，术后不进行处理，术后观察移植皮片的存活时间。结果对照组移植心脏存活时间为（7．86±1．57）d，与对照组比较，MR1组、抗B7组和联合处理组的移植心脏存活时间均得到显著延长，但联合处理组延长最为明显，均超过150d；MR1组和抗B7组移植心脏组织病理学检查均呈慢性排斥反应改变，而联合处理组未见明显慢性排斥反应征象。联合处理组移植的供者来源皮肤存活时间均超过50d，而无关供者来源的皮肤则被很快排斥；对照组两种来源的皮肤移植后存活时间均较短。结论联合阻断CD28／B7与CD40／CD40L共刺激通路可延长移植心脏存活时间，诱导出抗原特异性免疫耐受。     

抗CD8单抗与抗CD40L单抗联合应用对小鼠心脏移植后慢性排斥反应的影响

目的 探讨干预慢性迟发性超敏反应（DTH）与CD8^＋T淋巴细胞的细胞毒等效应机制对同种小鼠心脏移植后慢性排斥反应的影响。方法 建立小鼠颈部异位心脏移植模型，实验组以BALB／c小鼠为供者，C57BL／6小鼠为受者，术后0、2、6及14d腹腔注射抗CD8单克隆抗体（抗CD8单抗）200μg／d，术后0、2及4d腹腔注射抗CD40L单克隆抗体（抗CD40L单抗）250μg／d；同系移植对照组供、受者均为BALB／C小鼠，术后同期腹腔注射等量生理盐水；同种移植对照组以BALWc小鼠为供者，C57BL／6小鼠为受者，术后不使用上述单抗。观察各组移植心的存活时间及移植心组织病理学变化。结果同种移植对照组移植心的平均存活时间为7．3d；实验组与同系移植对照组移植心的存活时间均超过60d。同种移植对照组移植心呈典型急性排斥反应病理学改变；同系移植对照组移植心组织未见明显病理变化；实验组移植心呈现血管周围炎、间质纤维化和血管内膜增生等慢性排斥反应组织病理改变。结论 清除CD8^＋T淋巴细胞和阻断CD40／CD40L通路的处理方案虽可预防急性排斥反应，显著延长移植心的存活时间，但并不能阻止慢性排斥反应的发生。     

CD40/CD40L和B7-1/CD28在小鼠叶酸性肾病中的作用

目的研究CD40／CD40L、B7—1／CD28在肾小管间质浸润的免疫活性细胞、损伤的肾组织固有细胞上的表达以及其可能的作用。方法一次性腹腔注射叶酸制作CD1小时鼠叶酸性肾病模型。在第1、2、3、7、14、21天分别处死动物，取其右肾进行免疫组织化学染色；取左肾提取蛋白进行蛋白印迹分析；采血检测BUN、Scr。以抗B7—1功能性单克隆抗体（B7-1mAb）联合叶酸应用，观察21d后，采血行BUN、Scr检测，病理图像分析肾病变区域及保护率。结果小鼠在给予叶酸后第1天，CD40、B7-1在肾小管上皮表达上调，并持续至第21天。通过蛋白印迹半定量检测，CD40在各时间点实验组肾组织表达量均增加5倍以上（P均〈0．01），在间质区域浸润的免疫活性细胞上可见CD28和CD40L的表达。经B7-lmAb干预性治疗，小鼠死亡率从47．83％下降到11．01％。P〈0．01；BUN、Scr水平明显降低；肾组织保护率从7．45％上升至66．51％。结论在小鼠叶酸性肾病中．肾组织CD40／CD40L和B7-1／CD28的表达上调并参与了肾小管上皮细胞损伤、免疫活性细胞浸润和肾小管间质纤维化的过程。B7-1mAb干预治疗能减轻上述的肾损害，为肾间质纤维化的特异性免疫治疗提供新的途径。     

巨噬细胞CD40L表达在腹膜炎中的临床意义

目的：探讨巨噬细胞CD40配体（CD40L）表达与持续性不卧床腹膜透析（CAPD）腹膜炎发生发展的关系。方法：运用流式细胞仪观察CAPD患者急性腹膜炎时腹透透出液中巨噬细胞CD40L,表达,并与CAPD非腹膜炎患者比较,结果：急性腹膜炎发生时,透出液中表达CD40L阳性巨噬细胞数显著增多。巨噬细胞表达CD40L水平显著增加,与非腹膜炎患者比较有显著差异（P＜0．05,P＜0．01）,急性腹膜炎缓解后,患者透出液中表达CD40L阳性巨噬细胞数及巨噬细胞表达CD40L水平均较发作期显著降低（P＜0．05）,结论：CAPD腹膜炎时巨噬细胞高表达的CD40L对于限制腹膜炎的发生发展具有积极意义。     

RNA干扰技术阻断CD40/CD40L共刺激通路对小鼠移植心存活时间的影响

目的 探讨慢病毒介导RNA干扰(RNAi)技术阻断CD40/CD40L共刺激通路对小鼠移植心存活时间的影响.方法 以针对小鼠CD40基因的RNAi慢病毒载体在体外感染供者骨髓来源的树突状细胞(DC),制备低表达CD40的耐受性DC(Tol-DC).荧光实时定量聚合酶链反应及流式细胞术检测DC感染前后CD40 mRNA及DC表面抗原CD40、CD11c和MHCⅡ的表达.建立小鼠异位腹腔心脏移植模型.在小鼠异位心脏移植前7 d,经静脉给受者输注体外制备的低表达CD40的Tol-EC(慢病毒感染DC注射组),并设置单纯移植对照组和未感染DC注射组作为对照.观察各组移植心的存活时间,评定各组术后第7天移植心排斥反应的病理分级.结果 CD40-RNAi慢病毒载体在体外感染DC 48 h后,CD40 mRNA表达明显受到抑制,抑制率为80.9%;CD40表达明显下降,由(74.37±4.08)%降至(40.07±4.03)%(P＜0.05).单纯移植对照组、未感染DC注射组和慢病毒感染DC注射组移植心存活时间分别为:(8±2)d、(9±1)d和(14±4)d,慢病毒感染DC注射组移植心存活时间明显延长,并且移植心排斥反应病理分级显著降低,差异有统计学意义(P＜0.05).结论 阻断CD40/C40L共刺激通路可抑制异系T淋巴细胞的活化,从而抑制急性排斥反应,延长小鼠移植心的存活时间.     

RNA干扰阻断BT／CD28共刺激通路在小鼠心脏移植中的抗排斥作用

目的探讨RNA干扰（RNAi）技术阻断B7／CD28共刺激通路对小鼠异体心脏移植排斥反应的影响及其机制。方法经体外转录合成针对CD80 mRNA和CD86 mRNA序列特异性小片段干扰RNA（siRNA），转染供者骨髓来源的树突状细胞（DC），半定量逆转录聚合酶链反应、流式细胞仪检测DC转染CD80siRNA、CD86siRNA前后CD80 mRNA和CD86 mRNA的表达水平以及细胞表面CD80及CD86的表达情况。在小鼠异位心脏移植前7d，经静脉给受者输注经siRNA干扰后的DC（干扰DC组），同时设立同种异体对照组、环孢素A（CsA）治疗组（术后皮下注射CsA 5mg／d）、同系移植对照组和未干扰DC组（移植前输注未转染DC），观察各组移植心脏的存活时间，对移植物的排斥反应进行病理分级，并测定移植物组织中白细胞介素2（IL-2）、γ干扰素（IFN-γ）及IL-10的mRNA表达水平。结果siRNA转染DC后，其CD80 mRNA及CD86 mRNA的表达受到明显抑制，CD80、CD86的阳性率分别由84％和67％下降至35％和30％。与同种异体对照组和未干扰DC组比较，干扰DC组移植心脏存活时间明显延长（P〈0．01），组织排斥反应病理分级显著降低（P〈0．01），移植心脏组织中IL-2 mRNA和IFN-γ mRNA的表达水平明显降低（P〈0．01），而IL-10 mRNA的表达水平明显升高（P〈0．01）。结论利用RNAi敲减供者骨髓来源的DC表面B7分子的表达，以阻断BT／CD28共刺激通路，具有抑制小鼠心脏移植排斥反应的作用，其机理可能是通过诱导T淋巴细胞无能并使T辅助细胞分化向Tn2型方向偏移。     

CD4+CD25+T细胞联合CD154单抗抑制大鼠肝移植急性排斥反应的研究

目的探讨CD4 CD25 T细胞联合应用CD154单抗在抑制大鼠肝移植急性排斥反应中的作用。方法分离Lewis大鼠脾脏CD4 _CD25 T细胞后与DA大鼠脾细胞单向混合淋巴细胞反应行体外激活。用"二袖套法"行DA到Lewis的原位肝移植48例。A组为对照组;B、C组单独术前回输体外激活的CD4 CD25 T细胞或术后腹腔注射抗CD154单抗;D组联合应用CD4 CD25 T细胞和CD154单抗。每组大鼠12对。术后7 d各组处死6只受体,检测移植肝内T细胞亚群和细胞因子水平。余大鼠观察生存情况,死亡大鼠观察移植肝病理变化。结果D组受体生存期(52.00±10.64)d明显长于B、C组(P<0.01);移植肝内CD4 CD25 T细胞比例(16.43±4.28)%明显高于B、C组(P<0.05、P<0.01),而淋巴细胞浸润数量[(3.47±1.21)%×106]和(CD8 T细胞百分比(14.19±3.02)%明显低于B、C组(P<0.05、P<0.01);移植肝内白细胞介素- 2(IL-2)水平(6.44±1.83)ng/L低于B、C组(P<0.05),IL-10(43.72±7.55)ng/L和转化生长因子-β1(TGF-β1)(270.06±46.91)ng/L明显高于B、C组(P<0.05、P<0.01)。结论联合应用CD154单抗能明显增强CD4 CD25 调节性T细胞对大鼠肝移植急性排斥反应的抑制作用。     

CD40-CD40L在儿童持续性免疫性血小板减少症发病机制中的作用研究

目的：通过检测CD40-CD40L在持续性免疫性血小板减少症（Persistent ITP）患儿外周血单个核细胞中的表达情况,以揭示其在儿童持续性ITP发病机制中的作用。方法应用流式细胞术检测20例持续性ITP患儿治疗前后及20例对照组儿童外周血单个核细胞中CD40-CD40L的表达情况,用ELISA法检测血小板抗体（PAIgG）。结果与对照组比较,CD40和CD40L治疗前后的表达均增高（P＜0.01,P＜0.05）, CD40治疗前高于治疗后（P＜0.05）,CD40L在两组的表达则差异无统计学意义（P＞0.05）;CD40、CD40L的表达与PAIgG均呈正相关（r分别为0.713、0.746,P＜0.05）。结论 CD40-CD40L共刺激信号异常可能为儿童持续性ITP发病机制之一,阻断此共刺激途径可能获得较好的治疗效果。     

CD40-CD40L在儿童过敏性紫癜发病机制中的作用研究

目的探讨CD40-CD40L存儿童过敏性紫癜发病机制中的作用。方法研究对象为30例HSP患儿,正常对照组30例,应用流代细胞术检测其外周血单个核细胞中CD40－CD40L的表达情况,并观察实验组治疗前后CD40-CD40L的表达有无差异,结果与对照组比较,CD40L表达明妙增高,且治疗前表达高于治疗后（P〈0．05）,CD40表达增高,但与对照组及治疗前后比较差异均无显著性（P〉0．05）。结论HSP患儿外周血单个核细胞CD40L表达增高,且治疗前离于治疗后,表明其在HSP患儿免疫紊乱发病机制中可能起着重要作用。     

CD40 expression on graft infiltrates and parenchymal CD154 (CD40L) induction in human chronic renal allograft rejection

BACKGROUND: CD40-CD154 (CD40L) costimulatory signaling plays a pivotal role in the effector mechanisms of transplant graft rejection. In animal models, CD40-CD154 blockade induces long-term graft acceptance concurrent with an absence of chronic rejection (CR) lesions. Given the critical importance of CD40-CD154 interactions in the development of chronic transplant allograft rejection, the relevance of in situ CD40 and CD154 expression was assessed in human chronic renal allograft rejection. METHODS: The expression of CD40, CD154, CD68, and T-cell receptor (TCR)alpha/beta was analyzed by immunohistochemistry. Serial cryostat sections of snap-frozen core renal allograft biopsies were obtained from 30 renal transplant patients. Biopsy specimens received diagnoses of CR (N = 23) according to the Banff classification and were compared with controls (N = 7) consisting of stable allografts and normal kidney tissue. RESULTS: Striking CD40 staining of graft cellular infiltrates (P = 0.016) was observed in renal allografts with CR compared with controls. The CD40+ cellular infiltrates in CR were predominantly TCR alpha/beta + T cells and some CD68+ macrophages. These findings were contrasted by the low-level CD40 expression detected in glomeruli and tubules of CR and controls. However, glomerular induction of CD154 was observed in CR allografts (P = 0.028) as compared with controls. CD154 immunoreactivity was demonstrated on glomerular endothelial, epithelial, and mesangial cells. Moderate CD154 expression was detected on tubular epithelial cells, and only weak CD154 immunoreactivity was observed on the infiltrates in isolated CR cases. CONCLUSION: In human chronic renal allograft rejection, CD40 is expressed on graft-infiltrating cells of the T cell and macrophage compartments. CD154 expression is induced on glomerular and tubular epithelial cells during CR, demonstrating another novel source of CD154 expression. The data substantiate the potential contributory role of an interaction between CD40+ graft-destructive effector T cells and macrophages with CD154+ renal allograft parenchymal cells in the development of chronic renal allograft rejection.     

靶向CD40的shRNA干扰抗大鼠异体肢体移植急性排斥反应的实验研究

目的 探讨靶向CD40的RNA干扰对大鼠异体肢体移植急性排斥反应的影响. 方法以纯系SD大鼠为供体,纯系Wistar大鼠为受体,行同种异体右后肢移植.27只大鼠肢体移植后随机分为三组,A组:注射入梭华.Sofast.siCD40-2/pSilencer载体复合物600 μL;B组:注射Sofast-pSilencer4.1-CMV neo空载体复合物600 μL;C组:注射生理盐水600μL,以上均通过阴茎背静脉注射.观察移植物排斥反应征象及存活情况,并于第7天对产生免疫耐受大鼠进行混合淋巴细胞反应,同时进行组织学检查. 结果与B、C组相比,A组移植物发生排斥反应的时间及存活时间均显著延长,差异有统计学意义(P＜0.01)(＞13 d),未见排斥反应征象;B、C组均于术后近期发牛排斥反应.A组大鼠对供体的淋巴细胞呈现低反应性,移植的供体同系大鼠的肢体得以存活. 结论术后不应用免疫抑制剂的情况下,靶向CD40的shRNA干扰可以抗大鼠异体肢体移植急性排斥反应.     

Mechanisms of survival prolongation of murine cardiac allografts using the treatment of CTLA4-Ig and MR1

BACKGROUND: [corrected] The present study was undertaken to determine the role of costimulatory blockade in a murine cardiac transplant model. MATERIALS AND METHODS: We blocked the CD28/B7 and CD154/CD40 costimulatory pathways by transient administration of CTLA4-Ig and MR1 antibody to study the effects on allograft survival time, deviation of Th1 and Th2 cytokine secretion, and other mechanisms related to prolonged survival. RESULTS: Costimulatory blockade prolonged the mean survival time (MST) of cardiac allografts to 43 days for the treated group vs 8 days for the untreated group (P < .01). The costimulatory blockade down-regulated the expression of 2 Th1 cytokines (interferon-gamma [IFN-gamma] and interleukin-2 [IL-2]) and 2 Th2 cytokines (IL-4 and IL-10), reduced the numbers of graft-infiltrating CD4+ and CD8+ lymphocytes, and inhibited the expression of both perforin/GrB and FasL in allografts. CONCLUSIONS: Combined administration of CTLA4-Ig/MR1 inhibited acute rejection reactions in murine cardiac allografts, prolonging the survival of cardiac grafts through several mechanisms, including inhibition of Th1 and Th2 cytokine expression, graft infiltration by CD4+ and CD8+ T lymphocytes, and reduced both perforin/GrB and Fas-FasL.     

The Immunobiology of Inductive Anti-CD40L Therapy in Transplantation: Allograft Acceptance is Not Dependent Upon the Deletion of Graft-Reactive T Cells

CD40–CD40L costimulatory interactions are crucial for allograft rejection, in that treatment with anti‐CD40L mAb markedly prolongs allograft survival in several systems. Recent reports indicate that costimulatory blockade results in deletion of graft‐reactive cells, which leads to allograft tolerance. To assess immunologic parameters that were influenced by inductive CD40–CD40L blockade, cardiac allograft recipients were treated with multiple doses of the anti‐CD40L mAb MR1, which was remarkably effective at prolonging allograft survival. Acute allograft rejection responses such as IL‐2 producing helper cell priming, Th1 priming, and alloantibody production were abrogated by anti‐CD40L treatment. Interestingly, the spleens of mice bearing long‐term cardiac allografts following inductive anti‐CD40L treatment retained precursor donor alloantigen‐reactive CTL, IL‐2 producing helper cells, and Th1 in numbers comparable to those observed in naïve mice. These mice retained the ability to reject donor‐strain skin allografts, but were incapable of rejecting the original cardiac allograft, or a second donor‐strain cardiac allograft. Further, differentiated effector cells were incapable of mediating rejection following adoptive transfer into mice bearing long‐term allografts, suggesting that regulatory cell function, rather than effector cell deletion was responsible for long‐term graft acceptance. Collectively, these data demonstrate that inductive CD40–CD40L blockade does not result in the deletion of graft‐reactive T cells, but induces the maintenance of these cells in a quiescent precursor state. They further point to a tissue specificity of this hyporesponsiveness, suggesting that not all donor alloantigen‐reactive cells are subject to this regulation.     

Mechanism of allorecognition and skin graft rejection in CD28 and CD40 ligand double-deficient mice

BACKGROUND: It has been shown that simultaneous blockade of CD28- and CD40-mediated costimulatory signals significantly prolongs allograft survival. Although these results led to an expectation of the establishment of specific immunotolerant therapy for organ transplantation, it became evident that these treatments rarely resulted in indefinite allograft survival. To uncover the mechanisms underlying these costimulation blockade-resistant allograft rejections, we studied the process of allogenic skin graft rejection in CD28 and CD40 ligand (L) double-deficient (double-knockout [dKO]) mice. METHODS: Skin grafts from BALB/c or BALB.B mice were transplanted to C57BL/6 background dKO mice. The frequency of CD4+ and CD8+ T cells responding to alloantigens presented by direct or indirect pathways were defined by the use of a cytostaining assay. RESULTS: BALB/c skin grafts were rapidly rejected by dKO mice. This CD28 and CD40L independent allograft rejection was inhibited by the depletion of CD8+ T cells. In vitro studies indicated that CD8+ T cells from BALB/c skin-grafted dKO mice responded to donor antigen presented only by the direct pathway. Unlike major histocompatibility complex (MHC)-mismatched donors, allogenic skin grafts from MHC-matched donors were accepted by dKO mice. CONCLUSION: In the absence of CD28 and CD40 costimulatory signals, CD8+ T cells recognize MHC antigens by the direct pathway, resulting in the rejection of skin grafts from MHC-mismatched donors. In contrast, MHC-matched and non-MHC-mismatched donor skin grafts indefinitely survive in dKO mice. These results indicated that donor-host MHC matching may still be critical to costimulation blockade therapy for organ transplantation.     

Analysis of Intragraft Gene and Protein Expression of the Costimulatory Molecules, CD80, CD86 and CD154, in Orthotopic Liver Transplant Recipients

CD40-CD154 and/or CD28-CD80/86 costimulatory blockade induces long-term allograft survival in numerous animal models. Studies examining the expression of costimulatory molecules during acute cellular rejection (ACR) have been limited to renal and cardiac allografts. The aim of this study was to describe the relationship between intragraft costimulatory molecule expression in OLT recipients and ACR. Forty-five liver biopsies were obtained at reperfusion and day 7. Gene and protein expression of CD80, CD86 and CD154 were analyzed by RT-PCR and immunohistochemistry. CD154 protein expression was present in 13 of 18 patients with a RAI score of 4, but in only two of 14 patients with a RAI score of <4. There was a strong association between the RAI score and the presence of CD80 and CD154 immunoreactivity. CD86 protein expression did not correlate with the severity of ACR. In reperfusion biopsies CD154, but not CD80 or CD86, protein expression correlated with the total ischaemic time. There was no association between expression of costimulatory molecule genes and ACR. In conclusion, we have demonstrated an association between CD154 and CD80 protein expression and ACR in orthotopic liver allografts.     

Use of anti-CD40 ligand monoclonal antibody as antirejection therapy in a murine peripheral nerve allograft model

Monoclonal antibody directed against CD40 ligand prevents acute allograft rejection in several models of solid-organ transplantation. This study describes the use of CD40 ligand as antirejection therapy in a mouse peripheral nerve allograft model. C3H mice received 8-mm nerve isografts (n = 2) or nerve allografts from C57BL donors. Treated animals (n = 11) received anti-CD40 ligand antibody applied to the graft and by intraperitoneal injections postoperatively. At 3 weeks, nerve histology from treated animals was comparable to isografts, whereas untreated allografts demonstrated virtually no signs of regeneration. Walking-track analysis demonstrated a trend toward improved functional recovery in treated animals. In conclusion, blockade of the CD40 pathway suppresses nerve allograft rejection in mice, and facilitates regeneration comparable to isografts.     

Long‐Term Hepatic Allograft Acceptance Based on CD40 Blockade by ASKP1240 in Nonhuman Primates

Blockade of the CD40–CD154 costimulatory signal is an attractive strategy for immunosuppression and tolerance induction in organ transplantation. Treatment with anti‐CD154 monoclonal antibodies (mAbs) results in potent immunosuppression in nonhuman primates (NHPs). Despite plans for future clinical use, further development of these treatments was halted by complications. As an alternative approach, we have been focusing on the inhibition of the counter receptor, CD40 and have shown that a novel human anti‐CD40 mAb, ASKP1240, markedly prolongs renal allograft survival in NHPs, although allografts eventually underwent chronic allograft nephropathy. On the basis of our previous findings that a CD40–CD154 costimulation blockade induces tolerance to hepatic, but not cardiac, allografts in rodents, we tested here our hypothesis that a blockade of CD40 by ASKP1240 allows acceptance of hepatic allografts in NHPs. A 2‐week ASKP1240 induction treatment prolonged liver allograft survival in NHPs; however, the graft function deteriorated due to chronic rejection. In contrast, a 6‐month ASKP1240 maintenance monotherapy efficiently suppressed both cellular and humoral alloimmune responses and prevented rejection on the hepatic allograft. No serious side effects, including thromboembolic complications, were noted in the ASKP1240‐treated monkeys. We conclude that CD40 blockade by ASKP1240 would be a desirable immunosuppressant for clinical liver transplantation.