CD4+CD25+调节性T细胞对小鼠肝脏移植自发性免疫耐受的影响

目的 研究CD4+CD25+调节性T细胞在诱导自发性肝脏免疫耐受中的作用.方法 向受体和供体注射抗CD25抗体(PC61)后进行小鼠原位肝脏移植,观测其生存时间.术后20～30 d切取移植肝脏行HE染色,同时观察CD4+CD25+T细胞对CD4+T细胞和CD8+T细胞功能的影响.结果 去除受体而不是供体小鼠的CD4+CD25+T细胞可以导致肝移植排斥反应.而且,去除CD4+CD25+T细胞使移植物的白细胞浸润明显增多,组织损伤加重.同时,去除CD4+CD25+T细胞导致CD4+T细胞的增殖活性和CD8+T细胞的细胞毒活性明显增强.结论 受体来源的CD4+CD25+调节性T细胞在小鼠肝脏移植免疫耐受诱导中起重要作用.

Abstract：

Objective To examine the contribution of CD4+ CD25+ regulatory T cells to liver transplant tolerance. Methods After injection of anti-CD25 monoclonal antibody (mAb, PC61), mouse orthotopic liver transplantation was performed and survivals were determined. The paraffin-embedded sections of hepatic allografts were cut and stained with hematoxylin and eosin (HE). Furthermore, the effect of CD4+ CD25+ regulatory T cells on proliferative response of CD4+ T cells and cytotoxicity of CD8+ T cells was examined by depleting these regulatory T cells. Results Depletion of these cells in the recipients but not in the donors before liver transplantation caused rejection. Histological analyses of hepatic allografts with PC61 treatment showed extensive leukocyte infiltration and tissue destruction, whereas those in the control group showed minimal changes. Moreover, elimination of CD4+CD25+ T cells resulted in the enhancement of both proliferative response of CD4+ T cells and cytotoxicity of CD8+ T cells against donor-type alloantigen. Conclusions These results suggest that CD4+CD25+ regulatory T cells were important for tolerance induction to hepatic allografts.     

An investigation to assess the potential of CD25highCD4+ T cells to regulate responses to donor alloantigens in clinically stable renal transplant recipients.

Regulatory T cells are enriched within CD25(high)CD4(+) leukocytes, however their role in renal transplant recipients with stable function vs. recipients with biopsy-proven chronic allograft dysfunction remains unclear. We therefore studied the number, phenotype, and function of CD25(high)CD4(+) cells in the peripheral blood of 30 renal transplant recipients of living-related grafts, comprising 15 rejection-free recipients with stable graft function (Group A) and 15 with biopsy-proven chronic graft dysfunction (Group B). A higher absolute number of CD25(high)CD4(+) cells were present in the peripheral blood of rejection-free recipients (Group A) vs. those recipients with chronic graft dysfunction (Group B) (P = 0.019); but there was no significant difference with healthy volunteers (P = 0.084). In carboxyfluorescein diacetate succinimidyl ester-mixed leukocyte culture assays, depletion of CD25(high)CD4(+) revealed active regulation in 11 (74%) of 15 rejection-free recipient samples (Group A) in response to donor- but not third party-leukocytes, whereas no regulatory activity was observed in any samples from recipients with chronic graft dysfunction (Group B). In conclusion, these data provide evidence for the presence of an increased number of CD25(high)CD4(+) T cells with donor-specific regulatory activity in the peripheral blood of renal transplant recipients with stable graft function compared with recipients with chronic graft dysfunction.     

大鼠CD4^＋CD25^＋调节性T细胞的分离及功能鉴定

目的：研究利用免疫磁珠分选法稳定分离正常大鼠脾脏CD4^＋CD25^＋调节性T细胞的方法。方法：采用免疫磁珠两步法分离大鼠脾组织CD4^＋CD25^＋T细胞。首先采用藻红蛋白（PE）标记的抗CD25抗体和抗PE多功能磁珠试剂盒阳性分选CD25^＋T细胞,再用抗异硫氰酸荧光素（FITC）标记抗体和抗IgG磁珠阳性分选获得CD4^＋CD25^＋T细胞。分离后的细胞经流式细胞仪检测分离纯度,台盼蓝染色检测细胞存活率,体外增殖实验检测其对CD4^＋CD25^-T细胞的免疫抑制作用。结果：两次阳性分选后获得的CD4^＋CD25^＋T细胞纯度为（90.4±1.6）%,细胞存活率为（92.6±2.4）%。体外增殖实验表明,CD4^＋CD25^＋T细胞能明显抑制CD4^＋CD25^-T细胞的增殖（P〈0.01）。结论：采用免疫磁珠法两次阳性分选,可稳定地获得纯度理想并有免疫抑制功能的大鼠CD4^＋CD25^＋T细胞。     

CD4+CD25+调节性T细胞/辅助性T细胞17在脓毒症大鼠中的作用

目的 观察CD4+ CD25+调节T细胞(Treg)/辅助性T细胞17(Th17)细胞在脓毒症大鼠炎性免疫反应中的作用.方法 110只雄性SD大鼠随机分为正常对照组、假手术组、脓毒症(CLP)组,采用改良的盲肠结扎穿孔术(CLP)制作大鼠脓毒症模型.采用流式细胞术检测CD14+单核细胞表面人类白细胞抗原-DR基因(HLA-DR)表达率、Treg细胞及TH17细胞比例;酶联免疫吸附试验(ELISA)检测白细胞介素(IL)-6、IL-10、肿瘤坏死因子(TNF)-α、转化生长因子(TGF)-β、白细胞介素(IL)-17炎性因子蛋白表达.结果 与假手术组比较:(1)伴随着脓毒症病情的发展,大鼠出现明显的免疫抑制,CD14+单核细胞HLA-DR表达率＜30％,IL-10/TNF-α比值(27.41 ±7.04比6.63 ±2.60)明显增高(P＜0.01).(2)术后96 h脓毒症大鼠Treg细胞[(11.91±3.88)％比(6.57±2.60)％,P＜0.01]和Th17细胞[(5.14±0.29)％比(2.85±0.07)％,P＜0.01]表达明显增高.(3)术后96 h脓毒症组前炎性细胞因子IL-6[(42.31±15.89) ng/L比(6.32 ±3.18) ng/L,P＜0.01]、IL-10[(69.89 ±20.78) ng/L比(13.58±5.37) ng/L,P＜0.01]、TNF-α[(5.03±3.10) ng/L比(2.77±1.10) ng/L,P＜0.01]、TGF-β[(4.99±2.01) ng/L比(1.88±1.07) ng/L,P＜0.01]、IL-17[(92.77±11.64) ng/L比(7.58±2.30) ng/L,P＜0.01]表达明显增高.结论 伴随着脓毒症病情的发展,大鼠出现明显的免疫抑制;在大鼠脓毒症的发生发展中,Treg细胞介导的免疫抑制及Th17细胞介导免疫激活反应同时存在;脓毒症细胞因子微环境变化可能是导致Treg细胞/Th17细胞失衡的原因之一.     

雷公藤甲素预处理诱导Tregs细胞减轻小鼠肝脏缺血再灌注损伤的实验研究

目的 探讨雷公藤甲素(TPT)预处理减轻小鼠肝脏缺血再灌注损伤的作用及其机制.方法 将C57BL/6小鼠随机分为4组(15只/组):假手术对照组;假手术雷公藤甲素组;实验对照组;雷公藤甲素实验组.两个雷公藤甲素组小鼠术前1周每天给予雷公藤甲素0.1 mg/kg腹腔注射,术前1h加用一次,而两对照组同期仅给予等体积无菌生理盐水腹腔注射.肝脏缺血90 min再灌注24 h后分别采集各组小鼠的血液和肝组织,检测血清丙氨酸转移酶(ALT)、天冬氨酸转移酶(AST)水平.以及肝脏组织丙二醛(MDA)和超氧化物歧化酶(SOD)含量.光镜下观察肝组织的病理学变化.采用流式细胞术检测肝组织中CD4+CD25+Foxp3+T淋巴细胞占CD4+T细胞的百分比,采用实时聚合酶链反应检测肝组织中Foxp3 mRNA的表达.采用酶联免疫吸附试验检测血清中IL-10、IL-6、IL-1β和TNF-α细胞因子含量.结果 雷公藤甲素实验组和实验对照组小鼠血清ALT和AST明显升高,且雷公藤甲素实验组水平低于实验对照组(P＜0.05).假手术雷公藤甲素组和雷公藤甲素实验组与相应假手术和实验对照组相比MDA含量降低,SOD活性升高(P＜0.05).两假手术组肝组织结构正常,实验对照组可见明显的肝组织片状坏死,雷公藤甲素实验组肝小叶结构基本正常.假手术对照组、假手术雷公藤甲素组、实验对照组和雷公藤甲素实验组CD4+CD25+Foxp3+T淋巴细胞占CD4+T细胞的百分比分别为(7.55±1.87)%、(12.59±3.87)%、(7.85±1.07)%和(12.02±3.16)%.假手术雷公藤甲素组和雷公藤甲素实验组Foxp3 mRNA相对表达量高于相应的对照组(P＜0.05).雷公藤甲素实验组较实验对照组相比有升高血清IL-10,降低IL-6、IL-1β和TNF-α细胞因子的含量的作用.结论 雷公藤甲素可减轻小鼠肝脏缺血再灌注损伤,其机制可能与雷公藤甲素诱导上调体内CD4+CD25+Foxp3+调节性T淋巴细胞比例及增加IL-10分泌,抑制IL-6、IL-1p和TNF-α炎症细胞因子有关.

Abstract：

Objective To investigate the effect and related mechanism of triptolide pretreatment to prevent from ischemia/reperfusion (I/R) injury in mice liver. Methods Sixty male C57BL/6 mouse were randomized into four groups (15/group): A:sham group with saline , B: sham group with triptolide, C: saline I/R group, D: triptolide I/R group. The mice were pretreated with either saline or triptolide (0. 1 mg/kg/d) through intraperitoneal (ip) injection for one week. The mouse partial liver model of I/R injury was established, and samples were collected at 24 h after the I/R injury. Results Serum ALT and AST levels were significantly decreased and histological damage was significantly alleviated in the triptolide I/R group as compared with the saline I/R group (P＜0.05), the concentration of MDA in the triptolide groups was significantly decreased, while SOD activity was significantly increased compared with that of the saline I/R group (P＜0.05). The percentages of CD4+ CD25+ regulatory T cells (Tregs) cells among CD4+ T cells in groups A, B, C, and D were(7. 55 ± 1.87)%, (12. 59±3. 87)%,(7. 85±1.07)%, and(12. 02±3. 16)% in liver tissue, respectively. The expression levels of Foxp3 mRNA were significantly higher in the triptolide I/R group than those of saline I/R group (P＜0. 05). ELISA showed that triptolide could significantly inhibit the levels of IL-6, IL-Iβ and TNF-αand promoted the level of IL-10 in the serum (P＜0.05). Conclusion Pretreatment with triptolide could effectively prevent from liver I/R injury, which may be related to the induction of Treg cells by triptolide, the increase in the level of IL-10 in serum, and the inhibition of IL-6, IL-1β and TNF-α production in serum.     

肾移植患者术后外周血CD4+CD25+调节性T细胞的检测及其与瘦素水平的相关性

目的:了解肾移植患者术后外周血中CD4 CD25 调节性T细胞的比例和瘦素水平的变化及其临床意义,探讨CD4 CD25 调节性T细胞与瘦素水平的相关性。方法:应用放射免疫方法检肾移植患者及健康对照者外周血中瘦素的水平,流式细胞术检测外周血中CD4 CD25 调节性T细胞占CD4 T细胞的比例。结果:移植近期组(1年)与对照组患者血浆中瘦素浓度比较无差异,但移植远期组的瘦素浓度(2.5年)高于对照组和移植近期组。且外周血中CD4 CD25 调节性T细胞的比例与瘦素呈显著负相关(r=-0.83,P<0.01)。结论:肾移植术后的远期高瘦素血症可能对CD4 CD25 调节性T细胞具有负性调节作用,也许不利于移植耐受的维持。     

Mesenchymal stem cells attenuate liver fibrosis by suppressing Th17 cells – an experimental study

This study investigates molecular and cellular mechanisms involved in mesenchymal stem cell (MSC)‐mediated modulation of IL‐17 signaling during liver fibrosis. Mice received CCl₄ (1 μl/g intraperitoneally) twice/week for 1 month. MSCs (1 × 10⁶), or MSC‐conditioned medium (MSC‐CM), were intravenously injected 24 h after CCl₄ and on every 7th day. Liver fibrosis was determined by macroscopic examination, histological analysis, Sirius red staining, and RT‐PCR. Serum levels of cytokines, indoleamine 2,3‐dioxygenase (IDO), and kynurenine were determined by ELISA. Flow cytometry was performed to identify liver‐infiltrated cells. In vitro, CD4⁺ T cells were stimulated and cultured with MSCs. 1‐methyltryptophan was used for inhibition of IDO. MSCs significantly attenuated CCl₄‐induced liver fibrosis by decreasing serum levels of inflammatory IL‐17, increasing immunosuppressive IL‐10, IDO, and kynurenine, reducing number of IL‐17 producing Th17 cells, and increasing percentage of CD4⁺IL‐10⁺ T cells. Injection of MSC‐CM resulted with attenuated fibrosis accompanied with the reduced number of Th17 cells in the liver and decreased serum levels of IL‐17. MSC‐CM promoted expansion of CD4⁺FoxP3⁺IL‐10⁺ T regulatory cells and suppressed proliferation of Th17 cells. This phenomenon was completely abrogated in the presence of IDO inhibitor. MSCs, in IDO‐dependent manner, suppress liver Th17 cells which lead to the attenuation of liver fibrosis.     

尿毒症患者和肾移植受者外周血调节性T细胞表达的意义

目的探讨尿毒症患者和肾移植受者外周血CD4^＋CD127^-调节性T细胞（CD4^＋CD127^- Treg）的表达水平及意义。方法采用流式细胞术测定13例尿毒症患者（尿毒症组）、13例肾移植受者（肾移植组）和20例健康志愿者（对照组）外周血CD4^＋CD127^- Treg和CD4^＋CD25^＋CD127^- Treg占CD4^＋T细胞的比例。结果尿毒症组和肾移植组CD4^＋细胞中CD4^＋CD127^- Treg的比例明显低于对照组（P〈0．05,P〈0．01）;肾移植组CD4^＋CD25^＋CD127^- Treg的比例明显低于对照组（P〈0．05）。结论尿毒症患者外周血CD4^＋CD127^- Treg数量降低,免疫功能紊乱。肾移植受者外周血CD4^＋CD127^- Treg和CD4^＋CD25^＋CD127^-Treg数量降低,免疫反应性增强。     

雷公藤甲素预处理诱导Tregs细胞减轻小鼠肝脏缺血再灌注损伤的实验研究

Objective To investigate the effect and related mechanism of triptolide pretreatment to prevent from ischemia/reperfusion (I/R) injury in mice liver. Methods Sixty male C57BL/6 mouse were randomized into four groups (15/group): A:sham group with saline , B: sham group with triptolide, C: saline I/R group, D: triptolide I/R group. The mice were pretreated with either saline or triptolide (0. 1 mg/kg/d) through intraperitoneal (ip) injection for one week. The mouse partial liver model of I/R injury was established, and samples were collected at 24 h after the I/R injury. Results Serum ALT and AST levels were significantly decreased and histological damage was significantly alleviated in the triptolide I/R group as compared with the saline I/R group (P＜0.05), the concentration of MDA in the triptolide groups was significantly decreased, while SOD activity was significantly increased compared with that of the saline I/R group (P＜0.05). The percentages of CD4+ CD25+ regulatory T cells (Tregs) cells among CD4+ T cells in groups A, B, C, and D were(7. 55 ± 1.87)%, (12. 59±3. 87)%,(7. 85±1.07)%, and(12. 02±3. 16)% in liver tissue, respectively. The expression levels of Foxp3 mRNA were significantly higher in the triptolide I/R group than those of saline I/R group (P＜0. 05). ELISA showed that triptolide could significantly inhibit the levels of IL-6, IL-Iβ and TNF-αand promoted the level of IL-10 in the serum (P＜0.05). Conclusion Pretreatment with triptolide could effectively prevent from liver I/R injury, which may be related to the induction of Treg cells by triptolide, the increase in the level of IL-10 in serum, and the inhibition of IL-6, IL-1β and TNF-α production in serum.     

Expression of CD39 by Human Peripheral Blood CD4+CD25+ T Cells Denotes a Regulatory Memory Phenotype

We have shown that CD39 and CD73 are coexpressed on the surface of murine CD4⁺Foxp3⁺ regulatory T cells (Treg) and generate extracellular adenosine, contributing to Treg immunosuppressive activity. We now describe that CD39, independently of CD73, is expressed by a subset of blood‐derived human CD4⁺CD25⁺CD127lo Treg, defined by robust expression of Foxp3. A further distinct population of CD4⁺CD39⁺ T lymphocytes can be identified, which do not express CD25 and FoxP3 and exhibit the memory effector cellular phenotype. Differential expression of CD25 and CD39 on circulating CD4⁺ T cells distinguishes between Treg and pathogenic cellular populations that secrete proinflammatory cytokines such as IFNγ and IL‐17. These latter cell populations are increased, with a concomitant decrease in the CD4⁺CD25⁺CD39⁺ Tregs, in the peripheral blood of patients with renal allograft rejection. We conclude that the ectonucleotidase CD39 is a useful and dynamic lymphocytes surface marker that can be used to identify different peripheral blood T cell‐populations to allow tracking of these in health and disease, as in renal allograft rejection.     

调节性及辅助性T细胞在人类IgA肾病中的表达及意义

目的 探讨CD4+CD25high调节性T细胞（Treg）及辅助性T细胞亚群（Th1、Th2）比例失衡在IgA肾病（IgAN）免疫发病机制中的作用。 方法 用流式细胞仪检测IgAN患者外周血Treg及Th1、Th2的比例。以胞内染色技术检测叉头框蛋白3（FOXP3）的表达。Treg及Th1、Th2的比例与IgAN各项临床病理指标的相关性分析采用Spearman或Pearson相关分析法。 结果 IgAN患者外周血中Treg比例明显高于健康人[（2.14±0.82）％比（1.59±0.53）％，P ＜ 0.05]，与血IgA水平呈正相关（r = 0.397，P ＜ 0.05），与eGFR呈负相关（r = -0.376，P ＜ 0.05）。IgAN患者外周血中Th2细胞比例显著高于健康对照组[（2.57±0.72）％比（1.81±1.10）％，P ＜ 0.05]，与血IgA水平呈正相关（r = 0.468，P ＜ 0.05）。IgAN患者Th1/Th2比值显著低于健康对照组（5.75±1.89比12.73±9.79，P ＜ 0.05），但与临床各指标间没有相关性。 结论 IgAN患者体内存在T细胞亚群表达紊乱。Treg在外周血中的增多以及以Th2为优势的Th1/Th2失衡可能在IgAN的发病中起重要作用。     

Regulatory T cells contribute to the immunoregulatory effect on graft versus host reaction after liver transplantation in donor-dominant one-way MHC matching rats

Acute graft-versus-host disease following liver transplantation (LTx-aGVHD) poses a major diagnostic and therapeutic challenge, and the mortality rate is as high as 85%. Even the liver contains large numbers of lymphoid cells in the parenchyma and surgical damage of liver transplantation would induce an immunosuppressive, the incidence of LTx-aGVHD is just approximately 1–2%. CD4⁺CD25⁺regulatory T (Treg) cells have recently been shown to suppress proliferative responses of CD4⁺CD25⁻T cells to alloantigenic stimulation in vitro and are required for ex vivo tolerization of donor T cells, which results in their reduced potential to induce aGVHD after bone marrow transplantation. To investigate the role of Treg in LTx-aGVHD, we compared the proportional frequency of Treg in syngeneic liver transplantation recipients (sLT group), semiallogeneic liver transplantation recipients (Semi-LT group), LTx-aGVHD induced recipients (LTx-aGVHD group) and healthy controls. Here we show that replacement of (LewisXBN)F1 liver by Lewis liver alone in Semi-LT group was not sufficient to induce aGVHD, and all recipients grew in a normal pattern as the syngeneic LT from Lewis to Lewis rat. However, when 4 × 10⁸ of donor splenocytes were transferred simultaneously with LT, the morbidity of lethal aGVHD were 100%. A relative stable percentage of Treg, defined as CD4, CD25 and Foxp3, was detected in peripheral blood mononuclear cells (PBMCs) of sLT group compared with healthy controls. In early time after transplantation, no significantly change of Treg population was observed in these recipients after semiallogeneic liver transplantation in comparison with healthy controls (P > 0.05). However, Treg levels showed a relative increase 4 days after transplantation. Especially on 12th and 16th day after transplantation, there was significantly increased proportion of Treg cells compared with healthy controls (P < 0.05). The present of Treg decreased progressively in LTx-aGVHD group, which was significantly lower than group 1 and group 2 on the 12th and 16th day after liver transplantation (p < 0.05). In conclusion, recipients in semi-LT group harbor an increased percentage of Treg in peripheral blood compared with controls. Treg have an immunoregulatory effect on graft versus host reaction after liver transplantation. Additional donor splenocyte transplanted with the liver provoke the development of aGVHD after liver transplantation, and reversed the change of Treg in PBMCs as in Semi-LT group, which destroy the balance between Treg and conventional effector T cells which determine the outcome of aGVHD after liver transplantation.     

Functional CD25(bright+) alloresponsive T cells in fully immunosuppressed renal allograft recipients

BACKGROUND: Evidence from animal studies indicate a crucial role for CD25(bright+) regulatory T cells in transplantation tolerance. METHODS: To assess whether peripheral CD25(bright+) T cells control immune responses in immunosuppressed kidney transplant patients, we analyzed the suppressive capacities of these cells using mixed lymphocytes reactions. RESULTS: Allogeneic stimulation of patients peripheral blood mononuclear cells was associated with IL-2 production and T-cell proliferation. Depletion of CD25(bright+) T cells resulted in a 35% (median) higher IL-2 production and a 38% higher proliferative response against third party cells, showing that functional regulatory CD25(bright+) T cells were present (p = 0.03 and 0.02 respectively). In eight out of 11 patients, we also demonstrated regulation activity against donor-activated T cells (p = 0.03). These data were confirmed in coculture experiments with isolated CD25(-/dim) T cells plus CD25(bright+) T cells. At a 1:2 ratio, the CD25(bright+) T cells suppressed the proliferation of CD25(-/dim) donor- and third party-stimulated responder T cells. CONCLUSIONS: CD25(bright+) T cells with immune regulatory activities against anti-donor-responsive T cells are readily detectable in renal allograft recipients during treatment with full dosage immunosuppression. Whether CD25(bright+) T cells indeed play a role in graft acceptance after organ transplantation in patients remains to be elucidated.     

输注受者骨髓间充质干细胞对肝移植大鼠免疫功能的影响

目的 观察肝移植同时输注受者骨髓间充质干细胞(MSCs)对受者肝移植免疫功能的影响.方法 实验分为4组:A组SD大鼠只行剖腹探查;B、C、D组各组行Wistar-SD大鼠肝移植同时,C组提取受者MSCs同期经门静脉输注给受者,D组给予肌注CsA,B组给予门静脉输注生理盐水.观察术后第1、7、14天肝功能的变化、病理改变和细胞因子变化.结果 肝移植同时输注受者MSCs,谷氨酸转移酶、血清总胆红素较对照组显著降低,病理改变仅呈急性轻度排除反应,与肌注CsA组相似,而单纯移植组呈急性重度排除反应.术后第7天,白细胞介素(IL)-2和干扰素(IFN)-γ浓度,C组分别为(443.89±2.39)、(347.55±3.35)ng/L,B组分别为(600.36±2.98)、(373.77±1.81)ng/L,而IL-4和IL-10浓度,C组分别为(126.99±1.18)、(147.40±1.07)ng/L,B组分别为(102.02±0.94)、(111.03±1.15)ng/L,C组和B组比较,差异有统计学意义(P＜0.05).结论 肝移植同时输注MSCs,可通过抑制Th1细胞因子的表达,减轻受者对移植肝的排斥反应.     

Induction of long-term graft acceptance by a combination treatment of donor splenocytes and CTLA4Ig in a high responder rat liver transplantation model.

The CTLA4Ig has led to an improved survival rate in various allograft transplantation models. We investigated in a high responder rat model (Dark Agouti to Lewis) of orthotopic liver transplantation (ORLT), whether an additional adoptive cell transfer can enhance the effect of CTLA4Ig. After transplantation, recipients (n = 13/group) were treated with donor or third-party splenocytes alone or in combination with CTLA4Ig. Administration of splenocytes alone had no significant effect on survival (median 13 days, range 9-14) compared with untreated controls (median 10 days, range 8-12). CTLA4Ig monotherapy prolonged survival to a median of 30 days (range 11-150) but resulted in long-term graft rejection. The additional administration of third-party splenocytes showed no significant improvement over CTLA4Ig monotherapy. Only the combination of donor splenocytes with CTLA4Ig led to long-term graft acceptance (>150 days) without clinical and/or histological signs of rejection. A higher rate of apoptosis could be detected in livers at early time-points in long-term survivors receiving CTLA4Ig and donor splenocytes. Analysis of cytokine mRNA expression revealed a decrease of interleukin-2 at early time-points in all groups receiving CTLA4Ig; whereas, interferon-gamma was increased in long-term survivors receiving CTLA4Ig and donor cells or donor cells alone. The combination of CTLA4Ig and donor derived splenocytes is potent to induce long-term survival and graft acceptance. The mechanisms appear to involve the induction of an early inflammatory impulse and apoptosis.     

大鼠肝干细胞定位及形态学特征研究

目的 研究大鼠肝干细胞在肝脏的定位及其形态学特征。方法采用3’-甲基-4-二甲基偶氮苯诱癌建立大鼠肝癌模型,于造模第4周取肝脏组织进行免疫组织化学染色定位,同时分离干细胞,采用相差显微镜摄像、透射和扫描电镜摄像对分离的细胞进行形态学观察。结果 组织免疫化学发现细胞角蛋白(CK)18、19、CD_(34)、c-kit阳性。从成体大鼠肝脏分离的肝干细胞体积小、外形及胞核为圆形或椭圆形,可以稳定传代,细胞形态不发生改变;结论 成体大鼠肝干细胞位于汇管区,肝干细胞的成功培养为研究肝干细胞的生物学特性和临床应用提供了理论依据。     

CD44+-ESA+在结肠癌干细胞分选中的应用

目的 分选结肠癌细胞株SW480细胞中的CD133+-CD44+-ESA+亚群细胞,并观察其致瘤性.方法 用流式细胞仪分选SW480细胞中CD133+-CD44+-ESA+、CD133--CD44+-ESA+及CD133--CD44--ESA-亚群细胞.将这3组细胞分别接种于NOD/SCID小鼠,每组5只,观察肿瘤生长...     

Fates of CD4+ T cells in a tolerant environment depend on timing and place of antigen exposure

In experimental organ transplantation, tolerance is induced by administration of anti-CD40L mAb in conjunction with donor-specific splenocyte transfusion. Multiple, sometimes conflicting mechanisms of action resulting from this treatment have been reported. To resolve these issues, this study assessed the fates of graft reactive cells at different times and locations in the tolerant environment. Alloantigen-specific CD4(+) T cells transferred at time of tolerance induction (7 days before transplantation) became activated, expressed CD69 and CD44, and proliferated. Importantly, a large subset of this population became Foxp3(+) , more so in the lymph nodes than spleen, indicative of differentiation to a regulatory phenotype. In contrast, graft reactive CD4(+) T cells transferred to tolerogen-treated recipients at the time of transplantation failed either to proliferate or to differentiate, and instead were deleted via apoptosis. In untreated rejecting recipients graft reactive CD4(+) T cells became activated, proliferated and differentiated mainly in the spleen, and many of these cells were eventually deleted. These data resolve many apparent contradictions in the literature by showing that the timing of antigen exposure, the immunologic status of the recipients and secondary lymphoid organ location act together as key factors to determine the fate of graft reactive CD4(+) T cells.