过表达IL-17RLM的人脐带间充质干细胞对TNBS诱导的结肠炎小鼠脾脏淋巴细胞的免疫调节作用

目的:研究过表达白细胞介素17受体样分子的人脐带间充质干细胞(IL-17RLM-hUCMSCs)对三硝基苯磺酸(TNBS)诱导的结肠炎小鼠脾脏淋巴细胞的免疫调节作用,为炎症性肠病的干细胞治疗提供优化的种子细胞。方法:体外分离培养hUCMSCs,利用慢病毒载体向干细胞内转入IL-17RLM基因,构建IL-17RLM-hUCMSCs。采用TNBS诱导小鼠实验性结肠炎模型,无菌取炎症小鼠脾脏制备淋巴细胞悬液,在刀豆蛋白A(Con A)刺激下将淋巴细胞分别与不同浓度的IL-17RLM-hUCMSCs及hUCMSCs共培养,72 h后以淋巴细胞+Con A为阳性对照,CCK8法及CFSE标记法检测淋巴细胞的增殖情况;同时用流式细胞术检测T淋巴细胞亚群(Th1、Th2、Th17及Treg)比例的改变。结果:hUCMSCs及IL-17RLM-hUCMSCs均对ConA刺激下的淋巴细胞增殖有抑制作用(P0.05);当MSCs/淋巴细胞为1∶1~1∶10时,MSCs对淋巴细胞增殖的抑制作用呈现浓度依赖性。在有效浓度范围内,IL-17RLM-hUCMSCs较h UCMSCs抑制作用更强(P0.05)。hUCMSCs及IL-17RLM-h UCMSCs均能够下调结肠炎小鼠脾脏淋巴细胞的Th1和Th17细胞亚群比例,上调Treg细胞亚群比例,但IL-17RLM-h UCMSCs对Th17细胞亚群的抑制作用更显著(P0.05)。结论:IL-17RLM-hUCMSCs呈浓度依赖性地抑制TNBS诱导的结肠炎小鼠脾脏淋巴细胞增殖,且该作用优于h UCMSCs。同时,IL-17RLM-hUCMSCs可调节T细胞亚群的免疫平衡,且抑制Th17细胞亚群作用强于hUCMSCs。     

骨髓问充质干细胞联合胰岛移植对受体鼠树突状细胞成熟和功能的影响

目的:研究骨髓问充质干细胞(MSCs)对骨髓细胞(BMC)分化为成熟树突状细胞(DCs),以及MSCs联合胰岛移植对受体鼠BMC来源DCs成熟和功能的影响,以探讨MSCs如何通过DCs发挥免疫抑制作用的机制.方法:将BALB/c小鼠分离纯化骨髓MSCs按比例加入C57BL/6小鼠BMC,在含重组鼠粒细胞-巨噬细胞集落刺激因子(rmGM-CSF)和重组鼠白介素4(rmIL-4)的培养条件下制备DCs,加脂多糖(LPS)促DCs成熟,检测各组DCs免疫表型的变化,抗原摄取及其分泌白细胞介素-12的能力.观察MSCs联合胰岛移植的同种异基因糖尿病模型小鼠的血糖和组织学变化,并取受体鼠BMC体外诱导为DCs,检测成熟DCs免疫表型、抗原摄取和分泌IL-12能力.结果:体内外实验证明MSCs可使BMC来源的DCs表型CD11c,成熟表面标志CD83、协同刺激分子CD86和I-A<'b>表达明显降低(P<0.05),抗原摄取和分泌IL-12能力显著下降(P<0.01).MSCs联合胰岛移植,可抑制同种异基因受体鼠免疫排斥反应的发生.结论:MSCs可通过抑制BMC来源的DCs的成熟和功能,降低DCs抗原摄取和分泌IL-12能力,诱导免疫耐受,减轻对移植胰岛的排斥反应的发生.     

骨髓间充质干细胞联合胰岛移植对受体鼠树突状细胞成熟和功能的影响

目的:研究骨髓间充质干细胞(MSCs)对骨髓细胞(BMC)分化为成熟树突状细胞(DCs),以及MSCs联合胰岛移植对受体鼠BMC来源DCs成熟和功能的影响,以探讨MSCs如何通过DCs发挥免疫抑制作用的机制。方法:将BALB/c小鼠分离纯化骨髓MSCs按比例加入C57BL/6小鼠BMC,在含重组鼠粒细胞-巨噬细胞集落刺激因子(rmGM-CSF)和重组鼠白介素4(rmIL-4)的培养条件下制备DCs,加脂多糖(LPS)促DCs成熟,检测各组DCs免疫表型的变化,抗原摄取及其分泌白细胞介素-12的能力。观察MSCs联合胰岛移植的同种异基因糖尿病模型小鼠的血糖和组织学变化,并取受体鼠BMC体外诱导为DCs,检测成熟DCs免疫表型、抗原摄取和分泌IL-12能力。结果:体内外实验证明MSCs可使BMC来源的DCs表型CD11c,成熟表面标志CD83、协同刺激分子CD86和I-Ab表达明显降低(P0.05),抗原摄取和分泌IL-12能力显著下降(P0.01)。MSCs联合胰岛移植,可抑制同种异基因受体鼠免疫排斥反应的发生。结论:MSCs可通过抑制BMC来源的DCs的成熟和功能,降低DCs抗原摄取和分泌IL-12能力,诱导免疫耐受,减轻对移植胰岛的排斥反应的发生。     

天花粉蛋白对不同小鼠品系T细胞亚群分化的影响

为进一步探讨不同品系小鼠对天花粉蛋白(Tk)免疫抑制敏感性不同的机制,选择Tk高敏感品系(C57BL/6)和低敏感品系(C3H/He)小鼠,建立OVA特异性体外增殖系统,应用流式细胞术胞内细胞因子染色技术分析Th和Tc细胞亚群,real-time PCR检测细胞因子及相关转录因子的mRNA水平。发现Tk作用下,高敏感品系小鼠C57BL/6 IL-4阳性T细胞明显增多,表达IFN-γ阳性T细胞则显著减少。而低敏感品系C3H/He相关变化不明显。T细胞分化相关细胞因子IL-4、IL-10和IFN-γ及转录因子T-bet、gata-3的基因表达水平也呈现类似的格局。提示Tk发挥免疫抑制作用可能与其诱导的以Th2/Tc2为主的T细胞亚群有关,且这种诱导特定细胞亚群的作用在小鼠中和H-2b基因型相关。     

胞质转导肽-HBcAg18-27-Tapasin诱导C57BL/6小鼠T淋巴细胞分泌Th1型细胞因子及HBV特异性CTL的表达

目的 观察融合蛋白胞质转导肽(CTP)-HBcAg18-27-Tapasin诱导C57BL/6小鼠T淋巴细胞分泌Th1型细胞因子及HBV特异性细胞毒T淋巴细胞(CTL)的表达.方法 C57BL/6小鼠随机分为实验组CTP-HBcAg18-27-Tapasin、对照组CTPHBcAg18-27、HBcAg18-27-Tapasin及空白组(生理盐水).经肌肉免疫小鼠,ELISA检测T淋巴细胞分泌细胞因子;流式细胞术(FCM)检测T淋巴细胞内的细胞因子;CCK-8法检测T淋巴细胞增殖活性.结果 实验组能有效刺激小鼠T细胞分泌Th1型细胞因子;FCM检测实验组融合蛋白诱导的CTL水平明显高于其他组;且实验组T淋巴细胞增殖活性明显高于对照组及空白组.结论 CTP-HBcAg18-27-Tapasin融合蛋白免疫C57BL/6小鼠后,能提高T淋巴细胞增殖活性,能有效刺激T淋巴细胞分泌Th1型细胞因子及增加CTLs的表达.     

同系大鼠骨髓间充质干细胞对同种异体胰岛刺激的T淋巴细胞的免疫调节作用

目的:研究同系大鼠骨髓间充质干细胞(Mesenchymal stem cell,MSC)对同种异体胰岛刺激的T淋巴细胞的免疫调节作用,以及对共培养胰岛胰岛素分泌的影响。方法:以Wistar大鼠胰岛作为刺激原,Lewis大鼠MSC及外周血T淋巴细胞作为共培养细胞,分为三组:实验组(A)20IEQ胰岛细胞、1×108 L-1 T淋巴细胞和1×107 L-1 MSCs共培养;药物对照组(B)20IEQ胰岛细胞与1×108 L-1 T淋巴细胞共培养并加入0.25μg/ml CsA;阳性对照组(C)20IEQ胰岛细胞与1×108 L-1 T淋巴细胞共培养。CCK-8检测共培养3天时T淋巴细胞对同种异体胰岛刺激的反应性,ELISA检测共培养3天时上清液IFN-γ、IL-2、IL-4和IL-10的含量,以及共培养胰岛的胰岛素分泌功能。结果:MSC与CsA均可抑制同种异体胰岛刺激的T淋巴细胞增殖,A组T淋巴细胞增殖率(17.10±2.7)%与B组(14.65±1.8)%间差异无统计学意义(P>0.05);C组IFN-γ、IL-2含量显著高于A组及B组,IL-10含量显著低于A及B组,差异有统计学意义(P<0.05);IL-4含量在A、B、C三组间差异均无统计学意义(P>0.05)。A组胰岛的胰岛素分泌水平显著高于B组和C组,差异有统计学意义(P<0.05);胰岛素刺激指数(2.37±0.52)显著高于B组(1.80±0.36),差异有统计学意义(P<0.05)。结论:MSC与CsA均可通过减少Th1类细胞因子的表达使受者Th1/Th2平衡向Th2方向偏移,抑制同种异体胰岛刺激的T淋巴细胞增殖。相对于CsA,MSC可以保持胰岛素高分泌水平和良好的糖刺激反应性,避免了CsA可能带来的毒性和副作用,具有一定的临床应用优势及前景。     

细粒棘球绦虫转Eg95-EgA31融合基因苜蓿疫苗诱导Balb/c小鼠免疫应答的动态观察

目的动态观察细粒棘球绦虫转Eg95-EgA31融合基因苜蓿疫苗免疫Balb/c小鼠后诱导的免疫应答。方法热絮凝法提取转基因苜蓿的叶蛋白,再用无菌双蒸水将叶蛋白提取液的浓度配制成20μg/μl。88只Balb/c小鼠随机分为2组,分别用100μl灌胃和10μl滴鼻免疫小鼠,每3天1次,连续免疫2个月。在末次免疫后0、2、4、6、8、10、12、14、16、18和20周各组随机剖杀4只小鼠,眼球取血,常规酶联免疫吸附法(enzyme-linked immunosorbent assay,ELISA)检测血清中IgG及其亚类和IgE水平;取脾,分离脾细胞,流式细胞仪(flow cytometr,FCM)检测脾CD4+和CD8+T淋巴细胞亚群的百分比,体外经脾细胞悬液或加入Eg粗抗原(EgAg)、伴刀豆球蛋白A(ConA)或脂多糖(LPS)刺激培养,四甲基偶氮唑盐比色法(MTT法)检测免疫鼠脾T淋巴细胞增殖情况,ELISA法检测脾细胞培养上清液中IL-12、IL-10、IFN-γ和TNF-α水平。结果在末次免疫后4～6周,2组免疫小鼠的血清IgG及其亚类和IgE水平升高,脾T淋巴细胞增殖水平升高,CD4+和CD8+T细胞亚群百分比分别升高,脾细胞培养上清液中IL-12、IFN-γ、TNF-α和IL-10水平分别升高。结论细粒棘球绦虫转Eg95-EgA31融合基因苜蓿疫苗在免疫早期(4～6周)可诱导免疫鼠脾T淋巴细胞增殖,产生Th1和Th2混合型免疫应答,CD4+和CD8+T细胞亚群在细粒棘球绦虫转Eg95-EgA31融合基因苜蓿疫苗诱导的保护性免疫机制中起重要作用。     

HMGB1对淋巴细胞增殖、凋亡及Th1/Th2、Tc1/Tc2漂移的影响

目的:探索HMGB1是否参与淋巴细胞免疫功能的调节.方法:系列浓度HMGB1单独或与ConA联合刺激培养小鼠脾淋巴细胞.MTT法检测细胞增殖,流式细胞术(FCM)检测细胞凋亡、细胞表面CD3、CD8及细胞内IL-4、IFN-γ表达.结果:(1)HMGB1时间-剂量依赖性调节淋巴细胞增殖,而不影响其凋亡.(2)不同HMGB1浓度和刺激时间不影响淋巴细胞Th1、Th2及Th1/Th2变化,但10 μg/L和100 μg/L HMGB1刺激12～24 h,Th1亚群占优势;培养12～24 h,淋巴细胞Tc1亚群明显减少,Tc2无变化.Tc1/Tc2变化显示,1 μg/L和10 μg/L HMGB1刺激,Tc1亚群占优势.(3)培养12～24 h,上清中IL-2增加,sIL-2R减少,IL-2/sIL-2R比例升高20～50倍,尤以10 μg/L HMGB1刺激明显.结论:低剂量HMGB1可增强淋巴细胞免疫功能.     

骨髓间质干细胞降低大鼠移植物抗宿主反应的实验研究

目的 探讨MSCs对GVHD的作用及其机制.方法 建立大鼠同种异体骨髓移植模型,同时输入供者的T淋巴细胞诱导出移植物抗宿主反应,联合或不联合移植供体来源的MSCs,观察受鼠的生存时间,同时利用RT-PCR法研究Th1/Th2淋巴细胞亚群的比例,用ELISA法检测移植后体内IL-4细胞因子的浓度.结果 GVHD组的平均生存时间为(17.30±2.33)天,实验组的平均生存时间为(24.10±2.36)天 , 与单独移植HSCs相比,MSCs与HSCs共移植明显延长的受鼠的生存时间.同时,GVHD组Th1/Th 2 细胞比值为1.29±0.06,IL-4因子的浓度平均为(14.84±2.59) pg/mL,实验组Th1/Th 2细胞比值为(0.77±0.14),IL-4因子的浓度平均为(40.09±13.99) pg/mL.MSCs与 HSCs 共移植降低了体内Th1/Th2淋巴细胞亚群的比例,提高了体内IL-4细胞因子的浓度.结论 MSCs与HSCs共移植能有效抑制HSCs移植后致死性GVHD的发生,延长生存时间,同时MSCs 可能通过作用于体内Th1/Th2淋巴细胞亚群的比例,促进体内IL-4细胞因子的分泌从而间接发挥了抑制GVHD的作用.     

日本血吸虫感染小鼠肠系膜淋巴结T细胞亚群的变化

目的:观察C57BL/6小鼠感染日本血吸虫(Schistosome japonicum,Sj)4～6周肠系膜淋巴结T细胞亚群的改变。方法:用Sj尾蚴腹贴法建立Sj感染的小鼠模型。4～6周后取肠系膜淋巴结做淋巴细胞计数,使用细胞内细胞因子染色的方法,利用流式细胞仪检测肠系膜淋巴结淋巴细胞中分泌不同细胞因子的T细胞亚群含量的变化。结果:Sj感染C57BL/6小鼠4～6周后,肠系膜淋巴结细胞数量明显增多;流式细胞仪检测发现肠系膜淋巴结中CD4+T细胞中分泌IFN-γ的Th1细胞增多1倍,分泌IL-4和IL-5的Th2细胞增多近20倍,Th1/Th2轴发生偏移;分泌IL-17的Th17细胞也增多近5倍;分泌IFN-γ的CD8+T细胞也增多1倍。结论:日本血吸虫感染C57BL/6小鼠4～6周肠系膜淋巴结细胞增多,并向Th2和Th17型细胞极化。     

骨髓Sca-1+间充质干细胞移植减轻小鼠迟发型超敏反应

 目的 探讨骨髓Sca-1+间充质干细胞（BM-MSCs）在迟发型超敏反应（DTH）小鼠中的免疫调控作用。方法 小鼠随机分为对照组及MSCs注射组。注射组于0、2及6 d腹腔注射Balb/c小鼠Sca-1+ BM-MSCs,对照组注射生理盐水。所有鼠在7和14 d时分别于背部皮下与足跖注射C57BL/6小鼠脾细胞。24 h后用千分尺测量小鼠足跖的肿胀,ELISA法测外周血细胞因子及FACS法测脾脏免疫细胞比例。结果 注射组小鼠足跖的肿胀程度（0.368 ? 0.126 mm）显著轻于对照组（0.731 ? 0.111 mm,p < 0.01）。注射组外周血中IL-10和TGF-β含量显著高于对照组（p < 0.05）;而IL-12和TNF-α水平显著低于对照组（p < 0.05）。注射组小鼠脾脏调节型T细胞、树突细胞的比例明显高于对照组。结论 BM-MSC通过上调抑炎因子和调节型免疫细胞的数量而减轻DTH小鼠的免疫反应。     

移植耐受诱导的异基因胎肝移植小鼠的免疫功能重建

本文用门静脉注射异型脾细胞加腹腔注射环磷酰胺方法，成功地诱导了成年Ｂａｌｂ／ｃ小鼠（Ｈ－２ｄ）对Ｃ５７ＢＬ／６（Ｈ－２ｂ）小鼠的免疫耐受。致死照射的耐受Ｂａｌｂ／ｃ小鼠用Ｃ５７ＢＬ／６（Ｂ６）小鼠的胎肝细胞移植后，无移植排斥产生。嵌合状态分析的结果表明，在胎肝移植后９０ｄ和２４０ｄ，重建的Ｂａｌｂ／ｃ小鼠的脾细胞分别有７４．４％和８３．７％来自于供体Ｂ６小鼠．证明Ｂ６小鼠胎肝造血干细胞已经在致死照射的Ｂａｌｂ／ｃ小鼠体内稳定植入。免疫功能检测的结果表明，在胎肝移植后９０ｄ，照射Ｂａｌｂ／ｃ小鼠的免疫功能已经重建。     

The effect of a progesterone-induced immunologic blocking factor on NK-mediated resorption

Transfer of spleen cells from poly (I)-poly(C12U)-treated Balb/c mice to 6.5-days-pregnant Balb/c mice significantly increased the resorption rate (P less than 0.01) from 11% to 48%. The supernatant of progesterone-treated spleen cells from pregnant C3H mice abrogated the effect of spleen cell transfer. We conclude that by blocking NK activity in vivo, the progesterone-induced blocking factor favors the maintenance of pregnancy.     

Specific suppression of the local GVH reaction by F1 spleen cells

The local graft-versus-host (GvH) reaction in (C57BL/6 X BALB/c) F1 hybrid mice, assayed by popliteal lymph node enlargement, was specifically depressed by an injection of parental lymphocytes mixed with spleen cells from F1 mice pretreated with the same parental lymphocytes. Suppressor activity of CBF1 spleen cells was obtained 7 days after inoculation of parental lymphocytes, and peaked on day 10. The suppressive activity was induced by only spleen cells from CBF1 which was inoculated Balb/c lymphocytes, but not C57BL/6 lymphocytes. The lymphocyte subpopulation responsible for the suppressive activity was noticed in T cell population.     

研究嵌合状态与移植耐受关系的小鼠联体模型的建立

目的：探讨供体源的异基因血细胞嵌合体与受体耐受状态的关系,在不同品系的成年小鼠成功地建立了联体模型。方法：Ａｌｂ／ｃ（Ｈ－２＾ｄ）小鼠经尾静脉注入Ｃ５７ＢＬ／６（Ｈ－２＾ｄ,Ｂ６）脾细胞,同时Ｃ５７ＢＬ／６（Ｂ６）小鼠经尾静脉注入Ｂａｌｂ／ｃ小鼠脾细胞,２ｄ后,分别给Ｂａｌｂ／ｃ及Ｂ６小鼠腹腔注射环磷酰胺（ＣＹ）,可以明显延长Ｂａｌｂ／ｃ与Ｂ６联体小鼠的存活期（ＭＳＴ＝３０．４ｄ）。对经以上处理的     

Mitogenic effect of zinc on lymphocytes from strains of mice that are either high or low-responder to T-cell mitogens.

We have studied the in vitro mitogenic effect of ZnCl2 in cultures of lymphocytes from Balb/c or C57BL/6 mice which are high-responder or low-responder to T-cell mitogens respectively. Zn induced proliferation of spleen cells from Balb/c mice cultured without 2-ME. Higher levels of proliferation were observed in cultures with 2-ME. In contrast, Zn only induced proliferation of spleen cells from C57BL/6 mice in the presence of 2-ME. No response to Zn was observed in cultures without 2-ME, of spleen cells from either Balb/c or C57BL/6 mice depleted of plastic adherent cells. However, in cultures with 2-ME, Zn induced proliferation of non-adherent as well as plastic adherent cells from either strain of mice. In cultures without 2-ME, Zn induced proliferation of thymocytes from Balb/c mice, whereas did not show constant mitogenic effect on thymocytes from C57BL/6 mice. In contrast, Zn determined higher levels of proliferation of thymocytes from either strain of mice when cultured with 2-ME. Zn had earlier and stronger mitogenic effect on mature thymocytes of either strain of mice than in total thymocytes, both in cultures with or without 2-ME. However, Zn did not induced proliferation in cultures of immature thymocytes of either strain of mice.     

Effect of NK cells on GVHD in H-2 haploidentical bone marrow transplantation in mice

Objective: To study the effect of natural killer (NK) cells on graft-versus-host disease (GVHD) after H-2 haploidentical bone marrow transplantation (BMT) in mice. Methods :Murine model of H-2 haploidentical BMT was established by using Balb/c (H-2d) mouse as recipient, and Balb/c(H-2d)×C57BL/6 (H-2b) (H-2d/b) mouse as donor. Lethally irradiated Balb/c (H-2d) mice were transplanted with the bone marrow cells from Balb/c(H-2d)×C57BL/6(H-2b) (H-2d/b) mice containing donor spleen cells and/or NK cells. GVHD and survival rates were studied by observation of clinical manifestations and pathological changes. Results:In the group of bone marrow +spleen cells, GVHD was induced in 90% mice; but in the group plus with low amount of NK cells,GVHD was induced in 20% mice; and in the group transplanted with high amount of NK cells, GVHD was induced only in 10% mice. Compared to the group transplanted only with BM plus spleen cells, the incidences of GVHD in the latter two groups decreased significantly (P＜0.01) and the survival rates at different periods of 15, 30, 45 and 60 days increased obviously (P＜0.01 ). Conclusion: In mouse H-2 haploidentical BMT, alloreactive NK cells can reduce the incidence of GVHD and increase the survival rate.     

人免疫缺陷病毒Ⅱ型核心蛋白DNA疫苗的实验免疫研究

目的　检测HIV 2核心蛋白DNA疫苗诱导Balb c小鼠免疫应答的能力。方法　将表达HIV 2核心蛋白DNA疫苗质粒pVAXIgag肌注Balb c小鼠 ,分析CD4 、CD8 T淋巴细胞的数量、脾特异性CTL反应、血清中HIV 2的特异性抗体水平。结果　重组质粒pVAXI gag免疫组与空载体pVAXI及PBS对照组相比较差异显著 ,血清抗体滴度及淋巴细胞杀伤效应为P <0 .0 1,脾T细胞亚群的数量为P <0 .0 5。结论　HIV 2核心蛋白DNA疫苗能诱导Balb c小鼠产生特异性细胞免疫应答和体液免疫应答     

Mitogenic Effect of Zinc on Lymphocytes from Strains of Mice That are Either High or Low-Responder to T-Cell Mitogens

Abstract

We have studied the in vitro mitogenic effect of ZnCl₂ in cultures of lymphocytes from Balb/c or C57BL/6 mice which are high-responder or low-responder to T-cell mitogens respectively. Zn induced proliferation of spleen cells from Balb/c mice cultured without 2-ME. Higher levels of proliferation were observed in cultures with 2-ME. In contrast, Zn only induced proliferation of spleen cells from C57BL/6 mice in the presence of 2-ME. No response to Zn was observed in cultures without 2-ME, of spleen cells from either Balb/c or C57BL/6 mice depleted of plastic adherent cells. However, in cultures with 2-ME, Zn induced proliferation of non-adherent as well as plastic adherent cells from either strain of mice. In cultures without 2-ME, Zn induced proliferation of thymocytes from Balb/6 mice, whereas did not show constant mitogenic effect on thymocytes from C57BL/6 mice. In contrast, Zn determined higher levels of proliferation of thymocytes from either strain of mice when cultured with 2-ME. Zn had earlier and stronger mitogenic effect on mature thymocytes of either strain of mice than in total thymocytes, both in cultures with or without 2-ME. However, Zn did not induced proliferation in cultures of immature thymocytes of either strain of mice.     

Differential regulation of dendritic cell-T cell cross talk in the gut-associated lymphoid tissue

Dendritic cells (DC) play a central role in the regulation of immune responses by processing and presenting antigens to na?ve T cells. It has been proposed that after the initial interaction between DC and T cells, T cell-induced DC apoptosis serves as a down-regulatory mechanism that prevents the otherwise continuous activation of T cells by antigen-bearing DC. Our aim was to investigate and compare the susceptibility of Peyer's patch (PP)-derived and systemic (splenic) DC to antigen-specific T cell-mediated apoptosis in mice of different genetic background. Freshly isolated CD11c(+/hi)B220(-) DC from intestinal Peyer's patch and spleen from Balb/c and C3H/HeJ mice were co-cultured with syngeneic antigen-specific T cells in the presence or absence of the relevant antigen. In both mouse strains PP-DC showed higher susceptibility to T cell-mediated apoptosis compared to splenic ones, but levels of DC apoptosis were overall higher in C3H/HeJ mice compared to Balb/c. DC apoptosis was induced by both Th1 and Th2 antigen-specific clones and was strictly MHC class II-dependent in both strains, and interestingly we observed that although CD95-CD95L ligation played an overall minor part in T cell-induced DC apoptosis its role varied according to the mouse strain. Here, we demonstrated that PP-DC and splenic DC significantly differed in regard to their susceptibility to T cell-mediated killing. We interpreted these data as showing that the reciprocal regulation between DC and T cells in the gastrointestinal immune system is under stricter control compared to the systemic immune system and we hypothesized that these events are likely to contribute to the generation of fine balanced responses to intestinal antigens.