ICAM-1 参与系统性红斑狼疮中免疫球蛋白产生的实验研究

目的:探讨ICAM-1在系统性红斑狼疮(SLE)免疫球蛋白产生中的作用。方法:流式细胞术检测分析SLE患者、健康者、anti-CD3 Ab/IFN-α刺激健康者CD4~+T细胞及Pristane诱导的狼疮样小鼠及对照鼠中CD4~+T细胞的活化表型;分选获得Pristane处理小鼠来源的CD4~+T细胞和B细胞,并于体外交叉共培养,加入ICAM-1阻断抗体或同型对照抗体,ELISA检测培养上清中IgG和IgM水平。结果:SLE患者及anti-CD3 Ab/IFN-α刺激健康者CD4~+T细胞表达HLA-DR,CD69和ICOS等分子的细胞比例明显高于对照组。Pristane诱导的狼疮样小鼠CD4~+T细胞的活化程度也显著高于对照;Pristane诱导的狼疮样小鼠血清中抗snRNP和抗dsDNA自身抗体水平显著高于对照组;Pristane处理小鼠来源的活化CD4~+T细胞与B细胞共培养可以促进B细胞产生IgM和IgG。而经抗ICAM-1抗体阻断处理的培养上清中IgM含量低于对照组,而IgG含量显著高于对照组。结论:Pristane来源的活化CD4~+T细胞可促进B细胞分化,ICAM-1分子可能在B细胞分化早期发挥作用,但不利于IgM型向IgG型的类别转换,为ICAM-1在SLE中抗体类别转化的分子机制提供新的理论依据。     

桥本甲状腺炎患者γδ T细胞表面共刺激分子的表达及意义

目的探讨桥本甲状腺炎(HT)患者γδT细胞与自身抗体形成之间的关系及机制,寻找潜在的干预靶点。方法流式细胞术检测19例HT患者、15例健康对照者外周血及5例HT和5例单纯性甲状腺肿患者甲状腺组织中γδT细胞及其亚型的比例水平;流式细胞术检测γδT细胞表面活化分子CD69、HLA-DR以及共刺激分子CD40配体(CD40L)、诱导性共刺激分子(ICOS)的表达水平;ELISA检测γδT细胞和B细胞共培养上清中Ig G、Ig M水平,并通过抗体阻断实验分析参与B细胞抗体产生的分子机制。结果与健康对照组相比,HT患者Vδ1+γδT细胞比例明显增加;CD69、HLA-DR、CD40L、ICOS的表达水平均显著上调;γδT细胞和B细胞共培养上清中Ig G的水平显著增高,而添加抗CD40L和抗ICOS抗体能够使共培养上清中Ig G的表达水平明显下降。结论 HT患者的γδT细胞通过表达共刺激分子CD40L和ICOS为B细胞提供协同刺激信号辅助其产生抗体,提示γδT细胞在HT的发病机制中可能发挥着重要作用。     

ICOS/ICOSL、OX40/OX40L及CD40/CD40L在系统性红斑狼疮患者外周血表达水平及其临床意义

本研究旨在检测SLE患者外周CD4+T细胞表面ICOS、OX40、CD40L及B细胞表面ICOSL、OX40L、CD40分子的表达情况,并探索其临床意义。采用流式细胞术,我们检测SLE患者及健康对照外周CD4+T细胞表面ICOS、OX40、CD40L及B细胞表面ICOSL、OX40L、CD40分子的表达,并分析其与SLE临床指标的相关性。结果显示,SLE患者外周CD4+T细胞上ICOS、OX40、CD40L及B细胞上ICOSL、OX40L、CD40分子的表达均明显高于健康对照组(均P0.05),且SLE患者CD4+T细胞表面ICOS的表达与患者血清IgG水平呈现正相关,B细胞表面ICOSL的表达与患者血清抗dsDNA抗体水平正相关,B细胞表面OX40L的表达与患者血清抗核抗体水平正相关(均P0.05)。上述结果表明SLE患者外周CD4+T细胞上ICOS、OX40、CD40L及B细胞上ICOSL、OX40L、CD40分子均发生上调,并与SLE自身抗体水平呈现正相关,提示分别表达于T细胞和B细胞表面的ICOS/ICOSL、OX40/OX40L及CD40/CD40L分子,通过相互作用参与SLE的致病过程。     

ICOS/GL50信号在T细胞依赖性体液免疫应答中的作用

研究ICOS/GL5 0信号在T细胞体外增殖、细胞因子分泌以及B细胞抗体分泌中的作用 ,进一步探讨该信号途径在机体体液免疫应答中的作用机制。采用3 H TdR检测GL5 0 L92 9转染细胞和特异性鼠抗人GL5 0单抗对T细胞体外增殖的作用 ;ELISA法检测GL5 0 L92 9转染细胞和抗人GL5 0单抗对T细胞分泌IL 2、IL 10以及ICOS L92 9转染细胞和特异性鼠抗人GL5 0单抗对PWM介导的B细胞分泌抗体的效应。结果提示GL5 0 L92 9转染细胞能够促进经抗CD3单抗活化的T细胞增值和分泌IL 10 ,而抗GL5 0单抗可以阻断这些效应。ICOS分子与B细胞上GL5 0分子的结合上调PWM介导的B细胞分泌抗体而抗GL5 0单抗则下调这一效应。这些表明 ,ICOS/GL5 0信号途径在机体T细胞依赖的体液免疫应答反应中发挥着重要的调节作用     

抗ICOS抗体体外对哮喘大鼠血液和淋巴液CD4~+CD25~+Foxp3~+调节性T细胞数量及其功能影响

目的:研究抗ICOS抗体对哮喘大鼠外周血和淋巴液来源CD4+CD25+Foxp3+调节性T细胞(Treg)数量及其功能的影响。方法:抗ICOS抗体处理血液和淋巴液中单个核细胞(MNC),流式细胞仪检测MNC中CD4+CD25+Foxp3+T细胞百分率,酶联免疫吸附试验(ELISA)检测MNC培养液上清IL-10和TGF-β1含量。结果:末次激发后各个时间点收集MNC,体外培养96 h,各组淋巴液来源MNC体外培养体系中CD4+CD25+Foxp3+Treg细胞百分率均显著高于血液(P<0.05),哮喘组淋巴液和血液来源MNC体外培养体系中CD4+CD25+Foxp3+Treg细胞百分率均显著低于正常对照组(P<0.05),抗ICOS抗体组淋巴液和血液来源MNC体外培养体系中CD4+CD25+Foxp3+Treg细胞百分率显著低于哮喘组(P<0.05)。末次激发后0 h收集淋巴液来源和血液来源MNC培养上清中抗ICOS抗体组IL-10显著低于哮喘组和正常对照组(P<0.05);末次激发后不同时间点收集MNC培养上清中各组TGF-β1无明显差别。结论:用抗ICOS抗体阻断ICOS/ICOSL信号通路加重哮喘大鼠Treg细胞缺陷,并在哮喘激发早期0 h抑制血液和淋巴液来源MNC体外培养体系中CD4+CD25+Foxp3+Treg细胞分泌IL-10,但对于TGF-β1分泌无显著影响。     

负载灭活口蹄疫病毒树突状细胞对CD8+T细胞的旁位活化效应

目的:探讨在体外条件下负载灭活口蹄疫病毒(FMDV)树突状细胞活化CD8+T细胞的机制.方法:用重组粒细胞-巨噬细胞集落刺激因子(rmGM-CSF)和白介素-4(rmIL-4) 将小鼠外周血单核细胞诱导分化成树突状细胞(MoDCs),以信号阻断法从淋巴结T细胞制备CD8+T细胞,利用负载灭活FMDV的MoDCs与CD8+T细胞共培养,以FMDV+MoDCs+淋巴结T细胞作为对照,用ELISA检测不同时间培养上清液中IFN-γ的含量.用蛋白酶体抑制剂和溶酶体抑制剂处理MoDCs,2小时后再负载灭活FMDV,并与CD8+T细胞共培养,对照组则用FMDV+MoDCs+CD8+T细胞和FMDV+MoDCs,用ELISA检测不同时间培养上清液中IFN-γ的含量.结果:在共培养9小时,CD8+T细胞的IFN-γ释放量约为淋巴结T细胞IFN-γ释放量的1/6,随后,淋巴结T细胞和CD8+T细胞均产生少量IFN-γ.用灭活FMDV负载被lactacystin和氯喹处理的DCs与CD8+ T细胞共培养后9～12小时,CD8+T细胞产生IFN-γ显著减少,在共培养24小时,IFN-γ释放显著增多,并在36小时达到峰值,与对照组相比,差异有统计学意义.结论:负载灭活FMDV的MoDCs可以活化淋巴结T细胞,而且,还可通过非MHCⅠ和非MHCⅡ类分子依赖途径激活CD8+T细胞,此即旁位活化效应.     

可诱导共刺激分子的研究进展

可诱导共刺激分子（Inducible Costimulatory Molecule,ICOS)是新发现的表达于活化T细胞的共刺激分子，属CD28－CTLA－4家族。ICOS的小鼠配体B7RP－1和人类配体B7－H2具有不同的表达形式和条件。人类ICOS通路可被抗原－TCR信号和L-2激活。人刺激通路诱导T细胞分化，增殖并分泌IL－4，IL－10，IFN－γ和TNF－γ等细胞因子，对B细胞和CTL细胞免疫应答也有一定的影响。阻断ICOS通路会引起T细胞凋亡。ICOS与CD28通路无功能交叉性，在免疫应答过程中具有重要而且独特的应用。     

Foxp3转染小鼠CD4+CD25-T细胞抑制NK细胞活性

目的： 通过逆转录病毒载体转染Foxp3基因到小鼠CD4+CD25-T细胞,以研究体外诱导获得的调节性T细胞对NK细胞免疫活性的调节作用及其机制。方法： 携带Foxp3基因的逆转录病毒转染初始CD4+CD25-T细胞,以获得持续性高表达Foxp3的CD4+ T细胞模型。CD4+Foxp3+ T细胞与NK细胞共培养后,用［51Cr］标记的YAC-1细胞检测NK细胞的杀伤毒性。在TGF-β阻断实验中,通过Transwell共培养实验以及向细胞共培养体系加入抗TGF-β抗体,并检测NK细胞杀伤毒性。结果：逆转录病毒转染初始CD4+CD25-T细胞,成功建立了表达Foxp3的CD4+T细胞模型,转染后1周Foxp3阳性表达的T细胞比例为38.0%。CD4+Foxp3+ T细胞在与NK细胞共培养的24 h和48 h后,对NK细胞的细胞毒性杀伤效应的抑制率分别为42.9%和22.7%。在CD4+Foxp3+ T细胞与NK细胞的共培养体系中加入抗TGF-β抗体后,其抑制率分别由原来的42.9%(24 h)、22.7%(48 h)变为3.2%(24 h)、2.1%(48 h)。在Transwell共培养实验中与NK细胞直接接触的Foxp3+CD4+T细胞可以诱导NK细胞免疫抑制,而没有直接接触的Foxp3+CD4+T细胞则不能抑制NK细胞的杀伤作用。结论：强制性表达Foxp3的CD4+CD25-T细胞可以在体外发挥免疫抑制作用,可以抑制NK细胞的细胞毒性杀伤作用。转染 Foxp3的CD4+CD25-T细胞对NK细胞发挥作用依赖于细胞之间的直接接触,与转染后T细胞表面表达TGF-β有关。     

005 可诱导共刺激分子的研究进展

可诱导共刺激分子(Inducible Costimulatory Molecule,ICOS)是新发现的表达于活化T细胞的共刺激分子,属CD28/CTLA-4家族.ICOS的小鼠配体B7RP-1和人类配体B7-H2具有不同的表达形式和条件.人类ICOS通路可被抗原-TCR信号和IL-2激活.该共刺激通路诱导T细胞分化、增殖并分泌IL-4、IL-10、IFN-γ和TNF-γ等细胞因子,对B细胞和CTL细胞免疫应答也有一定的影响.阻断ICOS通路会引起T细胞凋亡.ICOS与CD28通路无功能交叉性,在免疫应答过程中具有重要而且独特的作用.     

BTLA信号对T细胞活化的起始和早期阶段的调节作用

目的:观察BTLA分子在T细胞上的表达并探讨其在各个阶段不同时相对T细胞活化的抑制。方法:分离人外周血单个核细胞,经阴性选择磁珠分离纯化获得T淋巴细胞。检测T细胞上BTLA、CTLA-4和PD-1的表达;用CD3抗体刺激T细胞活化,比较BTLA、CTLA-4和PD-1在T细胞活化过程中的动态表达。CD3抗体联合CD28抗体活化T细胞,在不同的活化时间,MTT法检测BTLA单抗8H9对T细胞增殖的影响。GM-CSF和IL-4体外诱导单核细胞分化成未成熟DC,CD40抗体刺激DC成熟,流式检测HVEM在DC上的表达。用DC诱导T细胞活化,加入游离8H9或抗HVEM抗体,阻断HVEM和BTLA结合,MTT法检测T细胞增殖。结果:静止T细胞组成性高表达BTLA,不表达CTLA-4和PD-1分子。T细胞活化后,BTLA分子表达有所降低,然后迅速回升至高水平。CTLA-4、PD-1分子在活化后两天几乎不表达,第三天开始表达并逐渐上升。8H9可以抑制CD3和CD28抗体活化的T细胞增殖。CD3和CD28抗体预先活化T细胞24小时或48小时后,再加入8H9仍然具有抑制效应,但不如在T细胞活化之初加入8H9的抑制效应。单核细胞诱导的不成熟DC上高表达HVEM,当DC成熟后,HVEM表达降低。用游离8H9或HVEM抗体阻断DC表面HVEM与T细胞表面BTLA结合,48小时之内均明显增强了DC诱导的T细胞增殖。结论:BTLA信号可以提高T细胞的活化阈值,在T细胞活化的起始和早期阶段发挥重要的负性调控作用。     

ERMAP is a B7 family-related molecule that negatively regulates T cell and macrophage responses

T cell activation and tolerance are tightly regulated by costimulatory and coinhibitory molecules. B7 family members play a crucial role in regulating immune responses. In this study, we identified erythroid membrane-associated protein (ERMAP) as a novel T cell inhibitory molecule. ERMAP shares significant sequence and structural homology with existing B7 family members in its extracellular domain. The ERMAP protein is expressed on the cell surface of resting and activated antigen-presenting cells (APCs) and in some tumor tissues. The putative ERMAP receptor is expressed on activated CD4 and CD8 T cells and macrophages. Both mouse and human ERMAP-IgG2a Fc (ERMAP-Ig) fusion proteins inhibit T cell functions in vitro. Administration of ERMAP-Ig protein ameliorates autoimmune diseases, including experimental autoimmune encephalomyelitis and type 1 diabetes, in mice. Anti-ERMAP antibody enhances macrophage phagocytosis of cancer cells in vitro. Furthermore, administration of an anti-ERMAP antibody inhibits tumor growth in mice likely by blocking the inhibitory effects of ERMAP on T cells and macrophages. Our results suggest that therapeutic interaction with the ERMAP inhibitory pathway may represent a novel strategy for treating patients with autoimmune disease or cancer.     

Hepatocytes induce functional activation of naive CD8+ T lymphocytes but fail to promote survival

Intraperitoneal peptide injection of TCR-transgenic mide or expression of antigen in hepatocytes leads to an accumulation in the liver of specific apoptotic CD8+ T cells expressing activation markers. To determine whether liver cells are capable of directly activating naive CD8+ T cells, we have studied the ability of purified hepatocytes to activate TCR-transgenic CD8+ T cells in vitro. We show that hepatocytes which do not express CD80 and CD86 co-stimulatory molecules are able to induce activation and effective proliferation of specific naive CD8+ T cells in the absence of exogenously added cytokines, a property only shared by professional antigen-presenting cells (APC). Specific T cell proliferation induced by hepatocytes was comparable in magnitude to that seen in response to dendritic cells and was independent of CD4+ T cell help or bystander professional APC co-stimulation. During the first 3 days, the same number of divisions was observed in co-cultures of CD8+ T cells with either hepatocytes or splenocytes. Both APC populations induced expression of early T cell activation markers and specific cytotoxic T lymphocyte (CTL) activity. However, in contrast to T cells activated by splenocytes, T cells activated by hepatocytes lost their cytolytic function after 3 days of co-culture. This correlated with death of activated T cells, suggesting that despite efficient activation, proliferation and transient CTL function, T cells activated by hepatocytes did not survive. Death could be prevented by adding antigen-expressing splenocytes or exogenous IL-2 to the co-culture, indicating that hepatocytes are not involved in direct killing of CD8+ T cells but rather fail to promote survival. Dying cells acquired a CD8low TCRlow B220+ phenotype similar to the one described for apoptotic intrahepatic T cells, suggesting an alternative model to account for the origin of these cells in the liver. The importance of these findings for the understanding of peripheral tolerance and the ability of liver grafts to be accepted is discussed.     

CD4+CD25+调节性T细胞在自身免疫病中作用的研究进展

CD4 CD25 调节性T细胞具有独特的免疫抑制功能,通过细胞接触和细胞因子机制抑制自身反应性T细胞的活化与增殖,在自身免疫病中发挥着重要作用。通过研究CD4 CD25 调节性T细胞在自身免疫病中的作用,将会揭示这类疾病的发病机制,从而为治疗自身免疫病提供一个新途径。     

IL-4 and IL-2 upregulate the expression of antigen B7, the B cell counterstructure to T cell CD28: an amplification mechanism for T-B cell interactions.

We recently generated mAb 104 which is specific for the B cell activation antigen Ag B7. With this we studied the regulation of Ag B7 expression on normal tonsillar B lymphocytes as well as the activities of B7+ and B7- activated B cells. SAC and to a lesser extent anti-IgM antibody upregulated Ag B7 and this was further enhanced by IL-2 and most notably IL-4. Ag B7 was expressed on virtually all sIgG+ and sIgA+ B cells and approximately half of the sIgD+ and sIgM+ B cells. SAC-stimulated B7+ B cells proliferated and produced IgM, IgG and IgA in response to IL-2 and IgM and IgG in response to IL-4. SAC-stimulated B7- B cells proliferated and produced only IgM in response to IL-2 and IL-4. Considering that Ag B7 has recently been shown to be the counterstructure of the T cell CD28 and that CD28 triggering strongly enhances cytokine production by T cells, it is likely that the CD28/B7 interaction represents an important amplification phenomenon in T-B cell interaction leading to humoral immune responses. The preferential expression of Ag B7 on IgG and IgA committed cells suggests that CD28/B7 interaction may be more specific to secondary antibody responses provided by memory T and B cells.     

CD4+ T cells play a major role for IgM and IgG anti-DNA production in mice infected with Plasmodium yoelii

The infection by a non-lethal strain of Plasmodium yoelii induces the formation of autoantibodies such as anti-DNA and anti-Sm antibodies in mice. The extent of the relative increase in serum levels of IgM and IgG anti-DNA and anti-Sm antibodies and their kinetics were found to be similar to those of anti-hapten antibodies and of total IgM and IgG levels. This strongly suggested that anti-DNA and anti-Sm autoantibody responses observed in malaria-infected mice are a result of polyclonal activation of B cells. The analysis of the IgG subclasses reacting with DNA antigen showed significant levels of the T cell-dependent isotypes, IgG1 and IgG2. The role of T cells in the activation of autoreactive B cells was confirmed by using athymic nude mice. Indeed, BALB/c-nu/nu and C57BL/6-nu/nu mice failed to produce IgG anti-DNA antibodies after infection with P. yoelii. Moreover, the reconstitution of BALB/c nude mice with lymph node cells from congenic euthymic BALB-Igb mice showed the activation of autoreactive B cells in nude mice by T cells from euthymic mice. Studies in mice depleted of CD4+ T cells strongly suggested that malaria-induced anti-DNA antibodies were almost entirely dependent on the presence of CD4+ T cells, as this depletion significantly decreased IgM anti-DNA antibodies and completely abolished the IgG anti-DNA production, including the IgG3 subclass in infected mice. In contrast, depletion of the CD8+ T cell subset had no effect on the production of autoantibody in malaria-infected mice. Our results indicate that CD4+ T cells play a major role for both IgM and IgG anti-DNA production during the course of malaria infection.     

Altered Th1/Th2 commitment in human CD4+ T cells with ageing

The human immune system undergoes continuous remodelling with the advancement of age. Since age-associated functional alterations in the immune system could be caused by a possible change in helper T cell regulation in elderly subjects, we comparatively studied the function of CD4+ T cells in peripheral blood obtained from both young and old healthy volunteers. Upon cell activation by phorbol myristate acetate and ionomycin, the proportion of CD4+ T cells containing interferon-gamma (IFN-gamma) was found to be greater in the old subjects. Utilizing a co-culture system, which activated CD4+ T cells via the TCR/CD3 complex and CD28, we found that CD4+ T cells from the old subjects secreted more IFN-gamma and IL-2, but less IL-4, than those from the young subjects. Upon cell activation by co-culture, CD4+ T cells from the old subjects expressed more CD26, CD40L, and LFA-1, but less CD30, than those from the young. These results together suggest that the microenvironment in which CD4+ T cells develop in older people may cause production of more cells committed to Th1 than that in younger subjects.     

IgM-enriched human intravenous immunoglobulin suppresses T lymphocyte functions in vitro and delays the activation of T lymphocytes in hu-SCID mice

Previous studies of an experimental human immunoglobulin preparation for intravenous use, containing normal pooled IgM (IVIgM), have shown its beneficial therapeutic effect in experimental autoimmune diseases. The mechanisms of its immunomodulatory activity remain however, poorly understood. In the experiments reported here, IVIgM inhibited the proliferation of various autonomously growing human lymphoid cell lines in vitro, as well as of MLR- and of PHA-stimulated human T-lymphocytes. These effects of IVIgM were observed at non-apoptotic concentrations and were stronger on a molar basis than those of normal pooled IgG for intravenous use (IVIg). Both preparations, when administered to SCID mice, repopulated with human peripheral blood mononuclear cells, delayed the expression of the early activation marker CD69 on both human CD4+ and CD8+ T-lymphocytes, activated by the mouse antigenic environment. The data obtained show that normal pooled human IgM exerts a powerful antiproliferative effect on T-cells that is qualitatively similar but quantitatively superior to that of therapeutic IVIg. Our results suggest that infusions with IVIgM might have a significant beneficial immunomodulating activity in patients with selected autoimmune diseases.     

B cells regulate expression of CD40 ligand on activated T cells by lowering the mRNA level and through the release of soluble CD40

The expression of CD40 ligand (CD40L) on activated T cells (CD4⁺ T cell clone MT9) is diminished when the T cells are cultured in the presence of B cells. This effect, observed both with normal tonsil B cells and with the B cell line JY, was detected after 6 h and sustained at least until 18 h of co-culture. Analysis of mRNA showed that CD40L mRNA levels were not modified after 6 h, but were significantly down-regulated after 18 h of co-culture with B cells. Although CD40L expression could not be detected by a CD40-Fc chimera, the molecule was still expressed at the membrane as shown with a polyclonal antiserum against CD40L (anti-TRAP). In addition, T cells activated in the presence of B cells were stained by a polyclonal antiserum against CD40, without the appearance of CD40 mRNA. These results indicated that a soluble form of CD40 (sCD40) bound to the expressed CD40L on T cells. The existence of sCD40 was confirmed by detection of sCD40 in B cell supernatants using a specific enzyme-linked immunosorbent assay. Collectively, these data show that B cells can regulate the expression of CD40L on activated T cells at least by two different mechanisms.     

Peptide-activated double-negative T cells can prevent autoimmune type-1 diabetes development

Autoimmune diseases may develop because of defective maturation, activation, differentiation and function of regulatory T cells. Previous studies have shown that exposure to donor antigen activates peripheral TCRalphabeta+CD3+CD4-CD8-NK1.1-, double-negative (DN) T cells, which specifically suppress anti-donor T cells and enhance survival of skin and heart grafts from allogeneic and xenogeneic donors. However, the role of DN T cells in preventing T cell-mediated autoimmune disease is unknown. Here, we analyzed the ability of DN T cells to recognize peptides expressed on self MHC and to suppress peptide-reactive CD8+ T cells, using the P14 mouse model that expresses a transgenic TCR specific for gp33 peptide presented on self MHC class I-Db. We found that injection of gp33 peptide resulted in increased DN and decreased CD8+ T cell numbers in the lymph nodes when compared to untreated mice. Injection of gp33, but not TCR-non-specific AV peptide, increased expression of T cell activation markers on DN T cells. Moreover, gp33-activated DN T cells suppressed proliferation of syngeneic CD8+ T cells via killing activated CD8+ T cells in an antigen-specific fashion in vitro. Furthermore, transferring gp33-activated DN T cells inhibited the development of autoimmune diabetes, suggesting that DN T cells may provide a novel therapy for T cell-mediated autoimmune diseases.