B淋巴细胞在抗CD45RB抗体诱导的移植免疫耐受中的作用

 目的: 探讨B淋巴细胞在抗CD45RB抗体诱导的移植免疫耐受中的作用。方法: 抗CD45RB抗体对BALB/c裸鼠进行预处理后制备脾脏单细胞悬液,与BALB/c小鼠T淋巴细胞和C57BL/6小鼠脾细胞混合培养,流式细胞术分析Th1、Th2、Treg和Tm淋巴细胞。以B6.μMT^-/-小鼠为受体、BALB/c小鼠为供体建立皮肤移植模型,移植后向受体鼠腹腔注射抗CD45RB单抗,监测脾淋巴细胞CD3⁺CD45RB^hi细胞比例。在混合淋巴培养过程中加入抗CD45RB单抗,分离B细胞,建立以BALB/c小鼠为供体、B6.μMT^-/-小鼠为受体的心脏移植模型,通过尾静脉注射B细胞给B6.μMT^-/-小鼠,观察受体鼠生存期和B细胞分布。结果: 在裸鼠体内用抗CD45RB抗体处理过的B淋巴细胞,与T淋巴细胞混合培养时,可使Treg和Th2淋巴细胞比例明显升高,Th1淋巴细胞的比例明显下降,Tm细胞无明显变化。在体内B淋巴细胞缺失的情况下,抗CD45RB抗体依然能够降低T细胞表面CD45RB的表达,与对照组B淋巴细胞存在组相比,抗CD45RB抗体对T淋巴细胞表面CD45RB下调更为快速,但最终CD3⁺CD45RB^hi T细胞比例无明显变化。体外抗CD45RB抗体处理过的B淋巴细胞可以延长受体鼠的生存时间。B6.μMT^-/-鼠在接受抗CD45RB抗体处理的B细胞并进行同种异体心脏移植后,B细胞可向胸腺迁移。结论: 在抗CD45RB抗体诱导的免疫耐受中,B淋巴细胞可能通过介导各T淋巴细胞亚群比例发挥着重要作用,且在中枢耐受中也起到一定作用,但是仅靠B淋巴细胞无法形成完全耐受。     

CD4~+CD25~+CD127~-T细胞在抗CD45RB抗体诱导免疫耐受中的作用

目的:研究CD4+CD25+CD127-T细胞在抗CD45RB抗体诱导的免疫耐受中所发挥的作用,从而阐明抗CD45RB抗体诱导免疫耐受作用的机制。方法:体内实验建立小鼠异位心脏移植模型,观察抗CD45RB抗体对移植物生存期的影响。体外实验观察抗CD45RB抗体对T细胞增殖抑制能力和对CD4+CD25+CD127-T细胞生成的影响。流式细胞术检测外周血和混合细胞中CD4+CD25+CD127-T细胞百分率,ELISA法检测血清和培养液中IL-2和IL-10含量,Real-TimePCR法检测脾脏和混合细胞中Foxp3基因的表达,移植心脏病理学观察。结果:抗CD45RB抗体显著延长移植物存活时间(P0.01),对ConA刺激引起的T淋巴细胞增殖具有明显的抑制能力(P0.05)。与对照组相比,实验组CD4+CD25+CD127-T细胞百分率和Foxp3 mRNA表达量均明显增加(P0.05),实验组IL-2水平较对照组明显降低(P0.05),但IL-10含量较对照组明显升高(P0.05)。病理结果显示对照组移植心脏出现典型细胞免疫性损伤病理改变,而实验组中几乎无炎性细胞浸润现象。结论:抗CD45RB抗体能显著延长移植物存活时间,其诱导免疫耐受机制与上调CD4+CD25+CD127-T细胞百分率和增加Foxp3 mRNA表达量有关。     

体外DCs在抗CD45RB抗体诱导免疫耐受中的作用机制

目的:探讨树突状细胞(dendritic cells,DCs)在抗CD45RB抗体诱导的免疫耐受中所发挥的作用,从而阐明抗CD45RB抗体诱导免疫耐受的机制。方法:采用DCs的常规诱导方法(rmGM-CSF、IL-4和LPS),在诱导过程中加入不同剂量的抗CD45RB抗体,成熟后利用流式细胞仪检测细胞表型、周期和吞噬能力,ELISA法检测IL-12分泌量,混合淋巴细胞培养检测DCs对T细胞增殖能力的影响。结果:DCs经抗CD45RB抗体处理后,CD11C和CD83表达升高,CD86表达下降,自身增殖和吞噬能力增强,但分泌IL-12和刺激T细胞增殖的能力明显下降。结论:耐受性树突状细胞(tolerogenic dendritic cells,tDCs)能显著抑制T细胞的增殖,它的产生是抗CD45RB抗体诱导免疫耐受的主要机制之一。     

GM-CSF与TGF-β联合处理小鼠供体骨髓细胞诱导特异性免疫耐受

目的:观察用GM-CSF和TGF-β在体外处理供体骨髓细胞(BM)后,输给受体鼠,观察能否诱导受体鼠对供体鼠淋巴细胞的特异性耐受。方法:体外用GM-CSF与TGF-β联合处理供体BM细胞诱导非成熟树突状细胞(iDC),并检测其成熟度。将BALB/c受体鼠随机分为3组,进行不同的预处理:(1)BM预免疫组:经尾静脉输入体外诱导的iDC,1×105细胞/只;(2)脾细胞预免疫组:经尾静脉输入C57BL/6供体鼠脾细胞,1×105/只;(3)阴性对照组:经尾静脉输入同体积的PBS。每组小鼠均需经过2次预免疫,每次间隔1周。第2次处理后1周,所有组的小鼠均接受相同剂量的C57BL/6来源的脾细胞腹腔注射,1×105/只。脾细胞攻击后3d,检测各组小鼠对C57BL/6小鼠脾细胞的同种异体反应水平,检测指标包括:采用单向混合淋巴细胞培养方法检测受体鼠淋巴细胞对供体鼠淋巴细胞的增殖指数;采用双抗体夹心ELISA检测受体鼠血清中IFN-γ和IL-10水平、FCM检测脾脏CD4+CD25highTreg细胞含量、及NK细胞抑制性受体KLRG1的表达、采用乳酸脱氢酶释放法检测NK细胞杀伤功能。结果:经GM-CSF和TGF-β体外处理的供体BM细胞能够抵抗脂多糖(LPS)促成熟的作用;与脾细胞预免疫组相比,经此BM细胞预处理的小鼠,再次遭遇供体小鼠淋巴细胞时,血清IL-10的含量降低(P0.05)、脾脏中CD4+CD25highTreg细胞的比例明显升高、对C57BL/6小鼠淋巴细胞增殖反应减弱(P0.01);NK细胞杀伤率降低。结论:用GM-CSF与TGF-β联合处理供体小鼠BM细胞在一定程度上能够诱导小鼠对供体小鼠脾细胞的免疫耐受,除Treg外,NK细胞可能也参与了诱导免疫耐受。     

TGF-β1诱导的调节性T细胞体内输注延长小鼠皮肤移植物存活

目的 利用TGF-β1体外诱导naYve T细胞分化为凋节性T细胞(Treg),通过体内输注延长小鼠皮肤移植物存活时间,并研究其相关机制. 方法 根据诱导条件不同分为3组:对照组(加入IL-2培养的C57BL/6小鼠T细胞)、MLR组(即混合淋巴细胞反应组,经同种抗原刺激活化的C57BL/6小鼠T细胞)和TGF-β组(经同种抗原刺激活化的C57BL/6小鼠T细胞,同时加入5.0ng/ml TGF-β1诱导).利用FACS检测CD4+CD25+T细胞比例,并用RT-PCR检测Foxp3的表达水平.建立小鼠皮肤移植模型,并于第0、l、2和3天输注上述细胞,观察皮肤移植物存活时间.术后第9天,取部分受鼠行移植物病理检测,用FACS检测脾脏中THl、TH2和CD4+CD25+Treg比例,并用Alamar Blue法检测淋巴细胞增殖能力. 结果 TGF-β组中CD4+CD25+T细胞比例高于对照组和MLR组(P<0.05),且其高表达Foxp3.将培养的细胞输注给受鼠后发现,输注MLR组细胞的受鼠其移植物平均存活时间(mean survival time,MST)为(9.4±1.3)d,低于对照组(P<0.05);而输注TGF-13组细胞小鼠MST为(22.8±1.9)d,较对照组和MLR组明显延长(P<0.05).病理检测亦显示TGF-β组受鼠移植物结构完整,无明显淋巴细胞浸润.FACS结果显示TGF-β组小鼠体内TH1细胞(CD4+TIM-3+)比例低于对照组和MLR组(P0.05),但低于对照组(P<0.05);而且TGF-β组中CD4+CD25+Treg比例明显高于对照组和MLR组(P<0.05).用Alamar Blue法检测受鼠外周淋巴细胞增殖活性显示,TGF-β组受鼠淋巴细胞增殖能力被明显抑制,低于对照组(P<0.05). 结论 TGF-β1可诱导T细胞分化为具有抑制能力的Treg将诱导后的细胞进行过继输注可使小鼠体内CD4+CD25+Treg比例升高,同时抑制TH1和TH2细胞分化扩增,并使得外周淋巴细胞增殖能力减弱,从而延长小鼠皮肤移植物存活时间.     

β2 GP1诱导的EAPS小鼠Treg/Th17细胞比率变化的研究

目的:观察EAPS疾病进展过程中小鼠外周血Th17细胞与CD4+CD25+调节性T(Treg)细胞的比率变化。方法:以重组人β2糖蛋白1(rhβ2GP1)主动免疫BALB/c小鼠建立EAPS模型,免疫12周后检测外周血浆抗β2糖蛋白1抗体(anti-β2GP1)、抗心磷脂抗体(a CA)、IL-17、IL-2、IL-6、TGF-β、活化部分凝血活酶时间(APTT)和血小板计数(PLT)及流产率。流式细胞术(FCM)检测小鼠PBMC中CD4+CD25+Treg及Th17细胞的比率。结果:与对照组相比,模型小鼠anti-β2GP1、a CA、IL-17、IL-2、IL-6水平明显升高,APTT延长,TGF-β降低,PLT升高,流产率提高,差异有统计学意义(P<0.05)。PBMC中CD4+CD25+Treg细胞频率8周前与对照组相比差异无统计学意义(P>0.05),12周后逐渐减少,明显低于对照组(P<0.05);Th17细胞频率逐渐升高,明显高于对照组(P<0.05);CD4+CD25+Treg/Th17比值明显低于对照组(P<0.05)。结论:EAPS小鼠外周血Th17/Treg细胞比率失衡可能在EAPS的发生发展中起重要作用。     

转录因子IRF8抑制Th17细胞分化并减轻T细胞免疫介导的小鼠结肠炎

 目的：转录因子干扰素调节因子（interferon regulatory factor, IRF）家族与Th17的发育密切相关,近年来发现Th17细胞在炎症性肠病的发病中发挥重要作用,本研究探讨IRF8对Th17发育及T细胞转染免疫介导的小鼠实验性肠炎的影响。方法：(1)采用流式细胞术分选野生型（WT）或IRF8全基因敲除(IRF8 -/-)小鼠脾脏和淋巴结的naive CD4 +T细胞(CD4 + CD62L +CD44 low),在Th1、Th2或Th17极化的条件下培养,采用流式细胞术检测Th1、Th2和Th17的比例。(2)建立实验性肠炎模型：采用免疫磁珠法分选WT或IRF8 -/-小鼠中的脾脏和淋巴结中CD4 +CD25 +Treg,WT小鼠的CD4 + CD45RB hi T细胞单独或者分别联合WT或IRF8 -/-小鼠的CD4 +CD25 +Treg腹腔注射给RAG1 -/-小鼠;WT或IRF8 -/-小鼠的naive CD4 + CD45RB hi T细胞腹腔注射给RAG1 -/-小鼠;观察上述小鼠每周体重的变化,第5周时处死小鼠,进行结肠炎病理评分和肠系膜淋巴结T淋巴细胞亚群检测。结果：(1)IRF8 -/-较WT的naive CD4 +T细胞在极化条件下向Th17细胞分化更明显(P<001),而对Th1和Th2细胞的分化无影响(P>0.05)。(2)CD4 + CD45RB hi T细胞转染给RAG1 -/-小鼠,IRF8 -/-较WT供体鼠引起的RAG1 -/-小鼠体重显著降低(P<0.05),结肠炎评分显著增高（P<0.05）,且肠系膜淋巴结中IL-17 +CD4 +细胞比例明显增高(P<0.01),而 IFN-γ +CD4 + 和 Foxp3 +CD4 +细胞比例无影响(P>0.05);IRF8 -/-小鼠的CD4 +CD25 +Treg对WT小鼠CD4 + CD45RB hi T细胞转染给RAG1 -/-小鼠诱发的免疫介导的结肠炎显示出正常的免疫抑制作用。结论：转录因子IRF8基因敲除促进CD4 +T细胞向Th17细胞分化,促进转染naive CD4 +T细胞诱导的实验性结肠炎的发生,IRF8基因敲除小鼠Treg细胞免疫抑制功能正常。     

宿主的遗传背景对呼吸道感染沙眼衣原体后Treg产生的影响

目的 探讨宿主的遗传背景对呼吸道感染沙眼衣原体后调节性T细胞(Treg)产生的影响.方法 对衣原体感染具有明显易感性差异的C57 BL/6(C57)和C3H/HeN(C3H)小鼠鼻腔吸入1×103 IFU沙眼衣原体小鼠肺炎菌株(Chlamydia muridarum,Cm),于感染后不同天数处死小鼠.利用细胞内细胞因子染色技术检测小鼠脾脏单个核细胞CD4+ CD25+T细胞、Foxp3+ CD4+ CD25+T细胞百分率,利用RT-PCR技术检测小鼠肺组织Treg细胞分泌的相关细胞因子IL-10和IL-2的mRNA表达水平,并比较Cm呼吸道感染不同时期C57和C3H小鼠Treg免疫应答水平的差异.结果 Cm感染在两组小鼠均诱导较高水平的CD4+ CD25+T细胞、Foxp3+ CD4+ CD25+T细胞产生及IL-10、IL-2mRNA表达.感染后第3天和第7天,高易感性的C3H小鼠脾脏CD4+ CD25+T细胞、Foxp3+ CD4+CD25+T细胞扩增水平,以及肺组织细胞因子IL-2 mRNA的表达水平均高于C57小鼠,感染后第14天,C3H小鼠IL-10 mRNA表达水平明显高于C57小鼠.结论 衣原体呼吸道感染在高易感性的C3H小鼠诱导高水平的Treg的增殖及Treg相关细胞因子IL-10、IL-2的表达,从而对衣原体特异的Th1免疫应答抑制作用增强,在小鼠衣原体呼吸道感染易感性差异中发挥重要作用.     

移植前诱导抗独特型抗体对小鼠皮肤排斥反应的抑制作用

目的 探讨抗独特型抗体诱导对异品系小鼠皮肤移植排斥反应的影响。方法 以C57BL／6小鼠脾细胞免疫Balb/c小鼠制备抗同种异品系抗体（Ab1),将Ab1与KLH交联后，免疫Balb/c小鼠诱导产生抗独特型多克隆抗体（Ab2),并以之为受体，观察Ab2对小鼠皮肤移植排斥反应的影响。结果Ab1交联KLH加弗氏佐剂免疫可有效地诱导抗独特型抗体（Ab2)产生。与对照组相比较，Ab2诱导组小鼠移植物存活时间明显延长。结论 移要有在受体体内诱导产生以移植物抗原为模拟抗原的抗独特型抗体，可对移植排斥反应产生有效的抑制作用。     

异基因骨髓间充质干细胞移植对EAE小鼠的治疗作用

目的 探讨异基因骨髓间充质干细胞(BMSC)对实验性自身免疫性脑脊髓膜炎(EAE)的治疗作用及相关免疫调节机制.方法 用髓鞘少突胶质细胞糖蛋白(MOG)多肽片段诱导建立C57BL/6J小鼠EAE模型;分离纯化培养BALB/c小鼠BM-SC,对EAE模型小鼠进行移植,移植前后对EAE小鼠进行神经功能评分;流式细胞术检测小鼠淋巴器官CD4+ CD25+ Foxp3+T细胞(Treg)的数量;荧光定量RT-PCR检测小鼠脾脏IL-2、IL-4、IL-17和IL-23 mRNA水平的表达.结果 异基因BMSC移植后小鼠神经功能评分明显改善;BMSC移植组小鼠胸腺、脾脏、淋巴结Treg数量显著增加;脾脏中IL-2、IL-17表达显著下降,同时IL-4、IL-23表达显著增加.结论 异基因BMSC移植通过调节免疫系统的Treg数量和CD4+T细胞分泌细胞因子的水平对EAE起治疗作用.     

Anti-CD4-mediated selection of Treg in vitro - in vitro suppression does not predict in vivo capacity to prevent graft rejection

Regulatory T cells (Treg) have been shown to play a role in the prevention of autoimmune diseases and transplant rejection. Based on an established protocol known to generate alloantigen reactive Treg in vivo, we have developed a strategy for the in vitro selection of Treg. Stimulation of unfractionated CD4(+) T cells from naive CBA.Ca (H2(k)) mice with C57BL/10 (H2(b)) splenocytes in the presence of an anti-CD4 antibody, YTS 177, resulted in the selection of Treg able to inhibit proliferation of naive T cells. In vivo, the cells were able to prevent rejection of 80% C57BL/10 skin grafts when co-transferred to CBA.Rag(-/-) mice together with naive CD45RB(high)CD4(+) cells. Purification of CD62L(+)CD25(+)CD4(+) cells from the cultures enriched for cells with regulatory activity; as now 100% survival of C57BL/10 skin grafts was achieved. Furthermore, differentiation of Treg could be also achieved when using purified CD25(-)CD4(+) naive T cells as a starting population. Interestingly, further in vitro expansion resulted in a partial loss of CD4(+) cells expressing both CD62L and CD25 and abrogation of their regulatory activity in vivo. This study shows that alloantigen stimulation in the presence of anti-CD4 in vitro provides a simple and effective strategy to generate alloreactive Treg.     

Prolonged acceptance of skin grafts induced by B cells places regulatory T cells on the histopathology scene

The participation of regulatory T (Treg) cells in B cell-induced T cell tolerance has been claimed in different models. In skin grafts, naive B cells were shown to induce graft tolerance. However, neither the contribution of Treg cells to B cell-induced skin tolerance nor their contribution to the histopathological diagnosis of graft acceptance has been addressed. Here, using male C57BL/6 naive B cells to tolerize female animals, we show that skin graft tolerance is dependent on CD25⁺ Treg cell activity and independent of B cell-derived IL-10. In fact, B cells from IL-10-deficient mice were able to induce skin graft tolerance while Treg depletion of the host inhibited 100% graft survival. We questioned how Treg cell-mediated tolerance would impact on histopathology. B cell-tolerized skin grafts showed pathological scores as high as a rejected skin from naive, non-tolerized mice due to loss of skin appendages, reduced keratinization and mononuclear cell infiltrate. However, in tolerized mice, 40% of graft infiltrating CD4⁺ cells were FoxP3⁺ Treg cells with a high Treg:Teff (effector T cell) ratio (6:1) as compared to nontolerized mice where Tregs comprise less than 8% of total infiltrating CD4 cells with a Treg:Teff ratio below 1:1. These results render Treg cells an obligatory target for histopathological studies on tissue rejection that may help to diagnose and predict the outcome of a transplanted organ.     

Suppression of the inflammatory immune response prevents the development of chronic biofilm infection due to methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is a common cause of prosthetic implant infections, which can become chronic due to the ability of S. aureus to grow as a biofilm. Little is known about adaptive immune responses to these infections in vivo. We hypothesized that S. aureus elicits inflammatory Th1/Th17 responses, associated with biofilm formation, instead of protective Th2/Treg responses. We used an adapted mouse model of biofilm-mediated prosthetic implant infection to determine chronic infection rates, Treg cell frequencies, and local cytokine levels in Th1-biased C57BL/6 and Th2-biased BALB/c mice. All C57BL/6 mice developed chronic S. aureus implant infection at all time points tested. However, over 75% of BALB/c mice spontaneously cleared the infection without adjunctive therapy and demonstrated higher levels of Th2 cytokines and anti-inflammatory Treg cells. When chronic infection rates in mice deficient in the Th2 cytokine interleukin-4 (IL-4) via STAT6 mutation in a BALB/c background were assessed, the mice were unable to clear the S. aureus implant infection. Additionally, BALB/c mice depleted of Treg cells via an anti-CD25 monoclonal antibody (MAb) were also unable to clear the infection. In contrast, the C57BL/6 mice that were susceptible to infection were able to eliminate S. aureus biofilm populations on infected intramedullary pins once the Th1 and Th17 responses were diminished by MAb treatment with anti-IL-12 p40. Together, these results indicate that Th2/Treg responses are mechanisms of protection against chronic S. aureus implant infection, as opposed to Th1/Th17 responses, which may play a role in the development of chronic infection.     

Effect of in vitroexpanded CD4CD25Foxp3 regulatory T cell therapy combined with lymphodepletion in murine skin allotransplantation

A promising approach for preventing allograft rejection involves shifting the balance between cytopathic and regulatory T cells to dominance of the latter cell type. Nonspecific lymphodepletion was conducted by administration of depleting anti-CD4 and anti-CD8 antibodies to reduce effector T cells and adoptive transfer of ex vivo-expanded host Treg cells by stimulation with donor dendritic cells to augment the Treg cell compartment. Evaluation of an MHC-mismatched skin allograft model revealed that combined therapy with these two protocols consistently induced modest prolongation of allograft survival, although all skin grafts were eventually rejected. The administration of IL-2/anti-IL-2 complexes significantly improved the efficacy of combination therapy via promoting the expansion of adoptively transferred Treg cells as well as endogenous recipient Treg cells. We conclude that Treg cell therapy combined with lymphodepletion is of practical benefit for the control of allograft rejection, but requires supplementary measures to promote immune tolerance.     

Effect of infusion of monoclonal antibodies to tumour necrosis factor‐receptor super family 25 on graft rejection in allo‐immune mice receiving autologous marrow transplantation

Significant barriers to transplantation exist for individuals who are pre‐sensitized to donor antigen and have high titres of donor‐reactive antibody. We report the effect of autologous bone marrow transplantation (BMTx) after myeloablation in pre‐sensitized mice along with the use of monoclonal antibodies (mAbs) to tumour necrosis factor‐receptor super family 25 (TNFRSF25), expressed on regulatory T (Treg) cells. C57BL/6 mice, which had been sensitized earlier with BALB/c skin allografts, received secondary BALB/c grafts after the primary grafts had been rejected. Subsequently, recipient mice underwent myeloablation with cyclophosphamide and busulphan and were injected with T‐cell‐depleted bone marrow from CD45.1 congenic donors (BMTx). Recipient mice underwent immunosuppressive treatment with rapamycin. A subgroup of mice was also treated with mAbs to TNFRSF25. Control mice were pre‐sensitized mice that received cyclophosphamide and busulphan followed by rapamycin. BMTx‐treated mice had significantly prolonged skin graft survival versus control mice. These mice also showed attenuated donor‐specific mixed lymphocyte co‐culture responses relative to controls, increased splenic Treg cells and markedly diminished serum anti‐donor IgG. Infusion of anti‐TNFRSF25 mAbs further augmented graft survival and increased graft‐infiltrating Treg cells. These mAbs also expanded murine and human Treg cells in vitro with the capacity to attenuate mixed lymphocyte co‐cultures using fresh peripheral blood mononuclear cells. Overall, this study delineates the roles of autologous BMTx and anti‐TNFRSF25 mAbs in expanding Treg cells and attenuating alloimmune responses in pre‐sensitized mice.     

Approach to withdrawal from tacrolimus in a fully allogeneic murine skin graft model

With few exceptions, transplant patients must take immunosuppressants throughout their lives. In this study, we used anti-T-cell receptor (TCR/CD3) monoclonal antibodies (mAbs) to induce immunological tolerance to alloantigens after withdrawal from tacrolimus in a fully allogeneic murine skin graft model. Skin grafts from AKR donor mice were maintained in C57BL/6 recipients by administering tacrolimus for one month. Anti-T-cell receptor (TCR) alphabeta mAb was administered to recipient mice on the day of withdrawal from tacrolimus administration. Seven days after mAb administration, the recipient mice were treated with various combinations of the following treatments: low-dose whole body irradiation, AKR bone marrow transfer (BMT), and anti-CD3 mAb administration. The control recipient mice did not receive treatment with either mAb, nor any other treatment. All the control recipient mice showed rejection of AKR skin grafts 42 days after tacrolimus withdrawal (mean skin graft survival: 77 days). Mice treated with a combination of anti-TCR alphabeta antibody, low-dose irradiation and AKR BMT showed stable chimerism in their peripheral blood lymphocytes and significantly prolonged skin graft survival (mean skin graft survival: >151.2+/-15.3 days). Mice given the combination of anti-TCR alphabeta mAb, anti-CD3 mAb, low-dose irradiation, and AKR BMT exhibited more stable chimerism but had earlier skin graft rejection (mean skin graft survival: 116.7+/-17.6 days) than the mice that did not receive anti-CD3 mAb. These results suggest that anti-TCR alphabeta mAb, but not anti-CD3 mAb, in combination with low-dose irradiation and BMT, is useful for long-lasting allograft survival after withdrawal from tacrolimus in mice with fully allogeneic skin grafts.     

Analysis of peripheral immune tolerance uncovers a mouse strain-dependent in situ type of graft tolerance

We screened various mouse strains [C57BL / 6, BALB / c, DBA / 2, CBA / Ca, (CBAxC57L / 6)F1, SJL, C3H] for induction of peripheral immune tolerance. Only CBA / Ca mice treated with anti-CD4 + CD8 monoclonal antibodies and grafted with allogeneic skin showed long-term graft survival (150 to > 200 days). Interestingly, T cells from the tolerant CBA / Ca mice rejected bone marrow / spleen cells of the skin graft donor strain and caused lethal graft-versus-host disease when transplanted to the donor strain. Furthermore, peripheral tolerance was easily broken: CBA / Ca mice could be reactivated to reject their tolerated grafts via immunization with (graft donor x recipient strain)F1 bone marrow cells. Thus, in contrast to the generalized nature of central tolerance, our experiments show that peripheral immune tolerance is strain dependent and locally restricted to graft tissue.