IL-7对胸腺T细胞及树突状细胞体外分化发育的影响

目的:探讨IL-7对胸腺T细胞及胸腺树突状细胞分化的影响。方法:摘取15～16日龄胎鼠胸腺进行体外器官培养(胚胎胸腺器官培养-FTOC),分别将细胞因子IL-7和培养基滴加在胸腺小叶上,12天后收集不同条件下经FTOC培养获得的胸腺细胞,流式细胞仪检测细胞表面分子CD4、CD8、CD11c、B220、Ia等的表达,通过光学显微镜观察细胞形态,通过细胞计数检测细胞数目的变化。再将经FTOC培养获得的胸腺细胞和异源的T细胞进行混合淋巴细胞反应,通过MTT法检测T细胞的增殖情况。结果:细胞计数结果表明添加外源性IL-7组的胸腺细胞数目明显减少,流式细胞仪检测结果显示其中胸腺CD4-CD8-双阴性细胞及CD8+单阳性细胞比例有所增加,而CD4+CD8+双阳性细胞比例显著下降,CD4+单阳性细胞比例没有明显变化;此外,B细胞和树突状细胞、NK细胞数量均有不同程度的增加。结论:IL-7在胸腺T细胞及胸腺树突状细胞的分化发育中发挥重要的调节作用。     

不同细胞因子诱导的小鼠骨髓树突状细胞亚群与小鼠脾脏树突状细胞亚群的比较

目的对粒-单集落刺激因子(GM-CSF)/白介素4(IL-4)或脱氧氟胸腺嘧啶配体(Flt3-L)体外诱导的小鼠骨髓来源树突状细胞(BMDC)亚群和正常小鼠脾脏DC亚群进行比较,探索诱生DC的特性。方法分离Balb/c小鼠骨髓细胞,分别加入含GM-CSF/IL-4或Flt3-L的培养液,体外培养7d,倒置显微镜观察细胞形态,并用流式细胞术检测CD11c、MHCⅡ、CD4、CD8α、CD45RA及Sirp-α分子;利用免疫磁珠从小鼠脾脏细胞中分离DC。结果两组细胞因子均可在体外诱导小鼠骨髓细胞分化发育为未成熟的DC;倒置显微镜下观察可见BMDCs表面有树突状突起,具有典型的DC形态学特点,与Flt3-L诱导的BMDC相比GM-CSF/IL-4诱导的DC体积大,树突长;但是,流式细胞术检测发现Flt3-L体外诱导的BMDCs与小鼠脾脏DC亚群更为相似。结论 GM-CSF/IL-4及Flt3-L均可在体外诱导小鼠骨髓细胞分化发育为DC,且Flt3-LDC亚群与脾脏DC亚群相似,有可能成为体外研究脾脏来源DC的一种方法。     

大剂量过敏原对致敏小鼠DC表面共刺激分子表达及调节性T细胞极化的作用

目的观察和比较致敏小鼠及正常小鼠DC表面共刺激分子表达及CD4+CD25+Foxp3+T数量的差异及大剂量过敏原在体外的作用。方法流式细胞仪检测致敏及正常对照小鼠脾脏DC表面分子CD11c、MHCⅡ、CD80、CD86表达。分离致敏及正常对照小鼠CD4+T细胞,流式细胞仪检测CD4+CD25+Foxp3+T细胞的数量。致敏小鼠脾脏DC、CD4+T细胞与10 mg/ml OVA或生理盐水共培养后,流式细胞仪检测并比较CD80、CD86等共刺激分子的表达及CD4+CD25+Foxp3+T细胞的数量。结果致敏小鼠脾脏DC表面共刺激分子CD80、CD86、MHCⅡ表达显著高于正常对照小鼠。10 mg/ml的OVA作用后,致敏小鼠脾脏DC表面共刺激分子CD80、CD86的表达明显降低。致敏小鼠脾脏细胞中CD4+CD25+Foxp3+T细胞数量显著低于正常对照小鼠。10 mg/ml的OVA作用后,致敏小鼠CD4+CD25+Foxp3+T细胞数量显著上升。结论大剂量过敏原在体外诱导致敏小鼠T细胞的不反应性,其机制与降低致敏小鼠DC共刺激分子表达,诱导调节性T细胞极化等有关。     

CpG ODN促进树突状细胞成熟的实验研究

目的：研究CpG ODN对小鼠骨髓来源的树突状细胞(bone marrow—derived dendritic cells,BMDC)分化成熟的影响。方法：以含非甲基化CpG基序的寡核苷酸(unmethylated CpG motif containing oligonucleotides,CpG ODN)刺激BMDC，流式细胞术检测DC膜表面CD80表达，ELISA检测DC分泌IL-l2水平，MTT法测定CpG ODN活化的DC刺激T细胞培殖能力。结果：CpG ODN可显著刺激DC表达CD80，分泌IL-l2，增强DC刺激T细胞增殖的能力。结论：CpG ODN可以有效促进DC的功能成熟。     

联合输注Flt3-L和GM-CSF表达质粒体内诱导小鼠DC的研究

目的:探讨联合输注Flt3-L和GM-CSF真核表达质粒体内诱导小鼠DC的方法并检测其抗原提呈功能。方法:采用尾静脉注射法分别输注Flt3-L及GM-CSF质粒,15d后收获小鼠脾脏;采用流式细胞术检测小鼠脾细胞CD11c、CD11b、B220、CD8α和NK1.1等表面标志以鉴定DC的比例及亚型;将体内诱导DC与HBsAg共孵育,然后刺激HBsAg预免疫小鼠的脾细胞并检测其分泌IFN-的水平。结果:联合输注Flt3-L和GM-CSF质粒小鼠的脾细胞达到4×108个细胞/脾脏、其中CD11c+细胞占20%以上,CD11c+细胞中CD11b+、CD11b-、B220+、CD8+、NK1.1+细胞的比例分别达17%、10%、26%、16%、7%左右;体内诱导DC负载HB-sAg后刺激HBsAg特异性淋巴细胞分泌IFN-γ的水平明显高于HBsAg单独刺激组。结论:采用小鼠尾静脉注射技术输注Flt3-L及GM-CSF质粒能够诱导CD11c+ DC的产生并包含多种亚型,体内诱导DC具备有效的抗原提呈功能。     

香烟烟雾提取物抑制树突状细胞诱导CD4~+T细胞分化为CD4~+CD25~+Foxp3~+调节性T细胞

目的探讨香烟烟雾提取物(CSE)暴露及抑制CD40-CD40L路径对小鼠髓源性树突状细胞(BMDC)诱导CD4~+T细胞分化为CD4~+CD25~+Foxp3~+调节性T细胞(Treg)的影响。方法使用40 ng/m L重组小鼠粒细胞-巨噬细胞集落刺激因子(rm GM-CSF)和10 ng/m L重组小鼠白细胞介素4(rm IL-4)联合诱导无特定病原体级健康雄性BALB/c小鼠骨髓来源的单个核细胞分化为树突状细胞(DC),流式细胞术检测小鼠BMDC表面CD40分子的表达,再采用免疫磁珠分选的方法从BALB/c小鼠脾脏细胞分离出CD4~+T细胞。将所培养出的小鼠BMDC与正常对照组小鼠脾脏细胞分选的CD4~+T细胞共培养,加入CSE及拮抗性CD40抗体,作用24 h;流式细胞术观察各组细胞CD4~+CD25~+Foxp3~+Treg的变化,液相芯片技术检测细胞上清液白细胞介素10(IL-10)、IL-6的水平。结果 BMDC与CD4~+T淋巴细胞共培养可以促进CD4~+CD25~+Foxp3~+Treg分化,经CSE刺激后,流式细胞术检测显示小鼠BMDC与CD4~+T细胞共培养后分化的CD4~+CD25~+Foxp3~+Treg数量降低,细胞上清液IL-10降低、IL-6的水平升高;而加入拮抗性CD40抗体细胞共培养组CD4~+CD25~+Foxp3~+Treg增加,液相芯片检测细胞上清液IL-10上升、IL-6的水平下降。结论 CSE减少CD4~+CD25~+Foxp3~+Treg数量,体外使用拮抗性抗CD40抗体阻断CD40-CD40L通路可以促进CD4~+T细胞分化为CD4~+CD25~+Foxp3~+Treg。     

全葡聚糖颗粒对DC诱导CD4+T细胞向Th17细胞分化的影响

目的研究全葡聚糖颗粒(whole glucan particle,WGP)对DC诱导CD4~+T细胞向Th17细胞分化的影响。方法采用重组小鼠FMS样酪氨酸激酶3配体(Flt3L)法诱导C57BL/6小鼠骨髓来源树突状细胞(BMDC)。用MACS磁珠分选法对OT-Ⅱ小鼠的脾脏和淋巴结中CD4~+T细胞进行纯化,加入特异性抗原卵清蛋白(OVA),与DC共培养。实验分组为:CON组、WGP组、TGP-β组、WGP+TGF-β组,培养5 d后,利用流式细胞术(FCM)检测各组中CD4~+T细胞增殖和Th17细胞变化情况,ELISA检测各组细胞上清液中IL-17A的含量,Q-PCR检测各组细胞中Th17细胞核转录因子维甲酸孤儿受体-γt(retinoid-related orphan receptor-γt,ROR-γt)mRNA表达水平。结果 TGF-β可以促进DC诱导CD4~+T细胞向Th17分化,而经WGP激发后,T细胞显著下调ROR-γt的转录水平,并减少对IL-17A的分泌。结论 WGP显著抑制TGF-β诱导CD4+T细胞向Th17细胞分化。     

LPS持续刺激对小鼠骨髓树突状细胞成熟的影响

目的　研究LPS持续刺激对小鼠骨髓树突状细胞 (DC)成熟的影响。方法　小鼠骨髓细胞用GM CSF培养 7d ,持续刺激组全程加入LPS ,短期刺激组在最后 48h加入LPS ,对照组不加LPS。流式细胞仪检测细胞表型和细胞摄取抗原的能力 ,ELISA检测细胞产生的细胞因子 ,混合淋巴细胞培养检测细胞提呈抗原的能力。结果　用LPS持续刺激的小鼠骨髓DC表达MHCⅡ、CD86、CD80和CD11c等分子和分泌TNF α和IL 12 (p70 )的能力并未增加 ,吞噬FITC OVA的能力显著升高 ,刺激同种异基因T细胞和刺激同种同基因T细胞增殖的能力亦显著低于LPS短期刺激组。结论　LPS持续刺激可抑制DC的发育成熟 ,可能是持续严重感染时免疫功能低下的原因     

HIV-1 C亚型密码子优化gp120负载人DC疫苗的构建及体外功能

目的构建HIV-1C亚型gp120负载人树突状细胞(dentriti ccell,DC)疫苗,并对其体外功能进行初步检测。方法利用Amaxa细胞核转染技术将pcDNA3.1-gp120质粒转染至人成熟DC,以Western blot检测gp120的表达。通过流式细胞仪检测DC表面共刺激分子的变化、混合淋巴细胞反应、CD8+T细胞表面活化分子CD25的表达及其分泌IFN-γ的变化。结果通过Western blot检测,gp120在DC中得到了正确表达。经流式细胞仪检测,DC表面分子CD80表达率由刺激前的33.34%上升至43.20%,CD86表达率由刺激前的60.08%上升至90.34%;负载gp120DC刺激淋巴细胞增殖率为86.72%;CD8+T细胞表面分子CD25表达率由刺激前的5.27%上升至74.21%,IFN-γ的表达率达37%。结论负载了HIV-1gp120的人树突状细胞能够显著刺激淋巴细胞的增殖、增强CD8+T细胞表面活化分子CD25表达以及促进CD8+T细胞分泌IFN-γ,为下一步DC治疗性疫苗的体内研究奠定基础。     

流式细胞仪三标记法检测白细胞介素-10对人树突状细胞表型的影响

目的观察白细胞介素(IL)10对体外培养人树突状细胞(DC)表型的影响,探讨流式细胞术三色荧光标记抗体检测细胞表面抗原的方法及意义。方法通过SCF、GMCSF、TGFβ1、Flt3和TNFα体外培养体系,将脐血CD34+造血干细胞诱导扩增获得DC,并于成熟过程中用重组人IL10进行干预。采用流式细胞术的三色荧光标记(FITC、PE、CY)单克隆抗体直接检测技术,分析细胞表型CD1a、CD11c、CD83、CD80、CD86和HLADR。结果IL10可下调成熟中DC表面CD11c、CD83、CD80和CD86的表达。结论IL10通过抑制DC表面黏附共刺激分子表达,可调节DC的递呈抗原功能;此外,采用流式细胞仪的三色荧光标记检测方法,不仅可以节约DC细胞用量,而且具有快速和准确的优点,值得推广应用。     

Flt3 ligand–receptor interaction is important for maintenance of early thymic progenitor numbers in steady‐state thymopoiesis

T‐cell production throughout life depends on efficient colonization and intrathymic expansion of BM‐derived hematopoietic precursors. After irradiation‐induced thymic damage, thymic recovery is facilitated by Flt3 ligand (FL), expressed by perivascular fibroblasts surrounding the thymic entry site of Flt3 receptor‐positive progenitor cells. Whether intrathymic FL–Flt3 interactions play a role in steady‐state replenishment of T cells remains unknown. Here, using competitive BM transplantation studies and fetal thymic organ cultures we demonstrated the continued numerical advantage of Flt3⁺ intrathymic T‐cell precursors. Sub‐kidney capsule thymic transplantation experiments, in which WT and FL^−/− thymic lobes were grafted into FL^−/− recipients, revealed that FL expression by the thymic microenvironment plays a role in steady‐state thymopoiesis. The deficiency of the most immature thymic T‐cell precursors correlated to upregulation of FL by thymic MTS15⁺ fibroblasts, suggesting that the number of Flt3⁺ progenitor cells may regulate the thymic expression of this cytokine. Together, these results show that FL expression by thymic stromal fibroblasts interacting with Flt3⁺ T‐cell progenitors is important for the physiological maintenance of early T‐cell development.     

Cultivation, proliferation and characterization of thymic macrophages.

Successful long-term culture of murine thymic macrophages was achieved by plating adherent thymic cells, in the presence of L cell-conditioned medium, on dishes coated with an extracellular matrix. Adherent thymic cells in normal conditions of in-vitro culture do not proliferate. Those maintained on plastic tissue-culture dishes, and exposed to L cell-conditioned medium, proliferate slowly to a limited degree and form very small colonies. In contrast, when cultured in dishes coated with an extracellular matrix formed by corneal endothelial cells, in the presence of L cell-conditioned medium, adherent thymic cells proliferate rapidly and after 12-21 days in culture form large colonies (about 3-5 mm in diameter). The proliferating cells were identified to be mononuclear phagocytes by their morphological appearance, their ability to ingest both bacteria and antibody-coated erythrocytes and by their nonspecific esterase activity. These cells were also shown to exhibit cell surface antigens that are characteristic of differentiated macrophages, e.g. Fc receptors and the specific macrophage cell surface marker F4/80. A high percentage of these cultured cells were found to bear I-A antigens. The adherent thymic mononuclear phagocytes could be trypsinized and passaged while maintaining both their ability to proliferate and their specific macrophage characteristics for a period of 70 days. Thus, monocyte-macrophage stem cells ae present in the thymus, and under appropriate in-vitro conditions, can be made to proliferate and mature to I-A-bearing macrophages.     

T cell developmental defects in 'viable motheaten' mice deficient in SHP-1 protein-tyrosine phosphatase. Developmental defects are corrected in vitro in the presence of normal hematopoietic-origin stromal cells and in vivo by exogenous IL-7

Defects in the gene that encodes SHP-1 protein tyrosine phosphatase result in multiple hematopoietic abnormalities and generalized autoimmunity in viable motheaten (me(v)) mice. These mice also exhibit early thymic involution and abnormalities in T cell development. Here, we describe the use of fetal thymic organ culture (FTOC) and bone marrow adoptive transfer to study the effects of SHP-1 deficiency on thymocyte development. Chimeric FTOC established with normal bone marrow placed onto deoxyguanosine-treated fetal thymic lobes or onto scid fetal thymic lobes generated T cells. Bone marrow from SHP-1-deficient me(v)/ me(v) mice generated decreased numbers of T cells in chimeric FTOC established using deoxyguanosine-treated thymi but generated normal numbers in chimeric FTOC established using scid thymi. However, scid fetal thymi seeded with me(v)/ me(v) bone marrow also exhibited morphological abnormalities and contained elevated numbers of macrophages. Addition of IL-7 to me(v)/ me(v) bone marrow-seeded scid FTOC led to increased cell numbers, particularly of macrophages. Intrathymic injection of IL-7 partially restored the ability of progenitor cells in me(v)/ me(v) bone marrow to populate the thymus of adoptive recipients. We conclude that abnormal T cell development in me(v)/ me(v) mice may in part be due to defects in the ability of bone marrow-derived accessory cells to provide bioavailable IL-7 to developing thymocytes.     

Influence of antibodies neutralizing cytokines on murine fetal thymic organ cultures

The role of cytokines in early T cell development was evaluated in a thymic organ culture system. Fetal thymic lobes from 14 day old mouse embryo's were cultured in the presence of antibodies neutralizing either IL-4, IL6 or TNF. In addition antibodies neutralizing TNF were added to cultures supplemented with human recombinant IL-2. The influence of these different treatments were evaluated by analyzing the different subsets generated after 12 days of culture with a panel of monoclonal antibodies. The antibody treatment did not result in dramatic changes in the cell populations nor did the anti-TNF inhibit the significant changes that are induced by the IL-2 treatment. These results show that based on the cellularity and thymocyte subsets no influence can be shown by inhibiting these cytokines. Other criteria, e.g. repertoire specificity have to be evaluated to address the influence of these treatments on early T cell development.     

Contact-mediated maturational effects of thymic stromal cells on murine thymocytes in culture.

The effect of direct contact between thymic stromal cells and thymocytes on differentiation markers and functions of the latter was studied. The thymic stromal cells included two epithelial and one fibroblast cell lines, previously described. Murine thymocytes were incubated with confluent monolayers of these cells or their supernatants for 24 hr, using monolayers of non-thymic cells and their supernatants as controls. Then, the thymocytes were tested for changes in expression of several surface antigens [Thy-1, Lyt-1, Lyt-2, L3T4, IL-2-receptor (IL-2R)], spontaneous [3H]thymidine incorporation (STI), lectin-induced proliferative response (PR) and lymphokine (IL-2 and IL-3) production. All three thymic stromal cell lines reduced the expression of Thy-1, Lyt-1 and Lyt-2 significantly. The expression of L3T4 was also reduced in some of the experiments, while IL-2R was not expressed by the thymocytes, neither before nor after the co-culture. The thymic stromal cell lines also increased the spontaneous [3H]thymidine incorporation and lymphokine production by the thymocytes and inhibited their proliferative response to lectins. Under the same experimental conditions, the culture supernatants of the thymic stromal cells and the non-thymic cells did not have any effect on the thymocytes, either when collected and used separately or when used in a co-culture system which allowed thymocyte contact with the medium but not with the stromal cells (Transwell system). These results suggest a specific effect of thymic stromal cells, epithelial as well as fibroblasts, on thymocyte maturation. The effect is mediated by direct cell contact and not by secreted factors.     

Feedback regulation of the secretion of a thymic hormone (thymulin) by human thymic epithelial cells in culture

The production of the thymic hormone, thymulin (FTS), was studied in primary cultures of human thymic epithelium by immunofluorescence using monoclonal anti-thymulin antibodies. The number of thymulin-containing cells and the thymulin level in the culture supernatant increased gradually during the culture. Addition of synthetic thymulin to the culture medium reduced significantly the increase of thymulin-containing cells. Conversely, addition of monoclonal anti-thymulin antibody from the beginning of the culture exacerbated the spontaneous increase of thymulin-containing cells and abrogated the effects of thymulin. Combined with similar data previously reported in vivo, these results demonstrate that thymulin is actively produced by cultured thymic epithelial cells and that its synthesis can be down-regulated by the hormone itself.     

The inflammatory cytokine,GM‐CSF,alters the developmental outcome of murine dendritic cells

Fms‐like tyrosine kinase 3 ligand (Flt3L) is a major cytokine that drives development of dendritic cells (DCs) under steady state, whereas GM‐CSF becomes a prominent influence on differentiation during inflammation. The influence GM‐CSF exerts on Flt3L‐induced DC development has not been thoroughly examined. Here, we report that GM‐CSF alters Flt3L‐induced DC development. When BM cells were cultured with both Flt3L and GM‐CSF, few CD8+ equivalent DCs or plasmacytoid DCs developed compared to cultures supplemented with Flt3L alone. The disappearance of these two cell subsets in GM‐CSF + Flt3L culture was not a result of simple inhibition of their development, but a diversion of the original differentiation trajectory to form a new cell population. As a consequence, both DC progeny and their functions were altered. The effect of GM‐CSF on DC subset development was confirmed in vivo. First, the CD8+ DC numbers were increased under GM‐CSF deficiency (when either GM‐CSF or its receptor was ablated). Second, this population was decreased under GM‐CSF hyperexpression (by transgenesis or by Listeria infection). Our finding that GM‐CSF dominantly changes the regulation of DC development in vitro and in vivo has important implications for inflammatory diseases or GM‐CSF therapy.     

In vitro lymphopoiesis in foetal thymic organ cultures: effect of various agents.

In this study 14-day-old foetal BALB/c mouse thymic lobes were removed and grown as organ culture in vitro for up to 6 days. The cultures were treated with agents which are known to alter the intracellular levels of cyclic nucleotides. The proliferative response of the lobes was judged by histological examination, 125I-UdR uptake and cell yields, of the lobes at various time intervals. The results indicate that agents which raise cyclic GMP levels stimulate the proliferative response of the lobes as judged by the various parameters used and that the response was largely restricted to the lymphoid cells. It has been suggested that most probably cyclic GMP is the positive signal for thymic lymphopoiesis perhaps not only in vitro but also in vivo.     

In vitromodels of T cell development

A number ofin vitrosystems are currently being used to study both thymocyte development and thymic stromal cell function. However, the usefulness of dispersed culture systems is limited since they often involve disruption of interactions within the normal three-dimensional architecture of the thymusin vivowhich are critical for normal development to proceed. In contrast, Fetal Thymus Organ Culture (FTOC) provides an experimental system where such interactions are maintained, thereby allowingin vitroaccess to key aspects of thymocyte development. More recently, Reaggregate Thymus Organ Cultures (RTOCs) have allowed detailed analysis of thymic stromal cell function, while retroviral transfection of thymocyte subsets under FTOC conditions provides a rapid means to investigate thymocyte development at the molecular level. Current use of the FTOC approach is summarised here, and where appropriate is compared to the use of dispersed culture systems.