CD40-CD40L共同表达于人内皮细胞及人动脉粥样斑块中

目的:探讨CD40和CD40L在人脐静脉内皮细胞及动脉粥样硬化斑块中是否可共同表达。方法:CD40及CD40L在内皮细胞表面的表达分别采用荧光技术、RT-PCR、流式细胞仪和Western blotting检测。人的动脉粥样硬化斑块中CD40及CD40L的表达采用免疫组化方法。结果:人内皮细胞能连续表达CD40及CD40LmRNA和蛋白, 并且细胞因子IL-1β、IL-6、TNF-α、INF-γ能明显刺激内皮细胞表达CD40、CD40L。人动脉粥样斑块中能共同表达CD40及CD40L, 而动脉壁的其它部分不表达。CD40L主要表达在斑块的肩部和底部, CD40在斑块中表达广泛。结论:人内皮细胞表面及粥样斑块中能共同高表达CD40和CD40L, 提示CD40及CD40L相互作用在动脉粥样硬化形成及发展中起重要作用。     

CD40L在肿瘤治疗中的作用

CD40L和CD40的相互作用在胸腺依赖的体液免疫和细胞免疫的调控中居于重要地位。研究表明,CD40L具有对肿瘤直接的生长抑制作用和对抗瘤免疫的激活作用。在对CD40L转染细胞诱导的抗肿瘤免疫的研究中,研究者们也取得了一些可喜的成果。这些研究进一步揭示了CD40L在肿瘤免疫治疗方面的应用前景。     

CD40系统与冠状动脉粥样硬化的关系

动脉粥样硬化(AS)是一种有免疫系统参与的慢性炎症性疾病.大量体外实验和体内实验均提示CD40/CD40L系统与AS的发生、发展及斑块的不稳定性密切相关,阻断CD40/CD40L的相互作用可能是抑制AS、稳定粥样硬化斑块的新举措.     

CD40L在肿瘤治疗中的作用

CD40L和CD40的相互作用在胸腺依赖的体液免疫和细胞免疫的调控中居于重要地位。研究表明，CD40L具有对肿瘤直接的生长抑制作用和对抗瘤免疫的激活作用。在对CD40L转染细胞诱导的抗肿瘤免疫的研究中，研究者们也取得了一些可喜的成果。这些研究进一步揭示了CD40L在肿瘤免疫治疗方面的应用前景。     

可溶性CD40的研究进展

CD40分子是属于肿瘤坏死因子受体（TNFR）超家族的Ⅰ型跨膜糖蛋白，可溶性CD40（sCD40）与膜型CD40（mCD40）共存，并具有与CD40L结合的能力，是CD40-CD40L作用的天然拮抗剂。研究显示健康人血清中存在低水平的sCD40，而肾脏疾病、肝脏疾病、血液病、神经系统疾病等患者血液和体液中异常高表达sCD40，且其水平与病程发展和预后有关，具有重要的临床意义。     

CD40和CD40配体的研究进展

ＣＤ４０是一种存在于Ｂ淋巴细胞、树突状细胞、造血前体细胞、上皮细胞及某些癌细胞表面的跨膜糖蛋白。由２７７个氨基酸组成，分子量为４５－５０ＫＤａ，是ＴＮＦ－Ｒ超家族成员。人ＣＤ４０基因定位于２０号染色体ｑ１１－３，小鼠基因位于２号染色体上，ＣＤ４０配体（ＣＤ４０Ｌ）由２６１个氨基酸构成，分子量为３４ＫＤａ，是ＴＮＦ超家族成员。基因位于ｘｑ２４。主要存在于活化的ＣＤ４＾＋Ｔ细胞表面，在ＣＤ８＾＋、ＫＦ     

CD40—CD40L与疾病

T淋巴细胞与抗原提呈细胞之间的信号传递调控着免疫系统的发展,其中CD40与其配体CD40L（CD154）的相互作用,不仅对T细胞活化和效应功能的表现起重要作用,且在抗感染,抗病毒及抗肿瘤和动脉粥样硬化症中扮演重要角色,本文综述了CD40－CD40L与人类疾病关系的研究进展。     

CD40和CD40配体的研究进展

ＣＤ４０是一种存在于Ｂ淋巴细胞、树突状细胞、造血前体细胞、上皮细胞及某些癌细胞表面的跨膜糖蛋白。由２７７个氨基酸组成，分子量为４５～５０ＫＤａ，是ＴＮＦ－Ｒ超家族成员。人ＣＤ４０基因定位于２０号染色体ｑ１１－３，小鼠基因位于２号染色体上。ＣＤ４０配体（ＣＤ４０Ｌ）由２６１个氨基酸构成，分子量为３４ＫＤａ，是ＴＮＦ超家族成员。基因位于ｘｑ２４。主要存在于活化的ＣＤ４＋Ｔ细胞表面，在ＣＤ８＋、嗜碱／肥大细胞表面也有表达。ＣＤ４０与ＣＤ４０Ｌ间的反应与Ｂ细胞活化、增殖、抗体的产生、生发中心的形成有关。反应的中断可导致免疫耐受，ＣＤ４０Ｌ缺陷可造成性联高ＩｇＭ综合征（ＨＩＭ）。     

CHD患者血清可溶性CD40L检测的临床意义

目的:探讨冠心病(CHD)患者血清可溶性CD40L(sCD40L)水平变化的临床意义.方法:应用酶联免疫吸附法(ELISA)对入选的90例CHD患者[急性心梗(AMI)患者28例,不稳定型心绞痛(UAP)患者35例,稳定型心绞痛(SAP)患者27例]的外周血sCD40L进行检测,并与30例正常对照者血清sCD40L的浓...     

氧化低密度脂蛋白及抗氧化剂对人脐静脉内皮细胞表达CD40和CD40 L的影响

目的探讨OX -LDL和VitE对人脐静脉内皮细胞表达CD40 和CD40L的影响。方法应用流式细胞技术检测细胞表面CD40和CD40L表达水平。结果低浓度OX -LDL(<200μg/L)可使内皮细胞表达CD40 和CD40L含量明显增加 ,具有浓度和时间依赖效应。高浓度(>200μg/L)OX -LDL刺激时 ,CD40 和CD40L表达明显下降。抗氧化剂VitE呈剂量依赖性部分逆转OX -LDL对内皮细胞表达CD40 和CD40L。结论OX -LDL刺激内皮细胞高表达CD40和CD40L可能是其致动脉粥样硬化的重要机制。     

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.     

CD40L表达在异基因造血干细胞移植中GVHD发生的意义

目的：初步探讨在异基因造血干细胞移植（HSCT）中发生移植物抗宿主病（GVHD）患者DC40L表达的变化以及意义。方法：HSCT治疗重型β-地中海贫血（n=12）和遗传性溶血性贫血（n=1）成功植入的儿童患者，其中脐血移植（UCBT）8例，异基因外周血造血干细胞移植(allo-PBSCT)5例，在移植前、移植后发生GVHD时采用流式细胞仪检测和比较外周血中CD40L和CD40的表达。结果：3例UCBT无GVHD，其余均发生了Ⅰ-Ⅳ度急性GVHD。急性GVHD发生时CD4^ CD40L^ 和CD8^ CD40LT细胞表达明显升高，allo-PBSCT者更明显；慢性GVHD发生时患者的CD40L^ 、CD25^ 和CD69^ 在CD4^ 和CD8^ T细胞上的表达亦增加。CD19^ CD40^ B细胞的表达在UCBT和allo-PBSCT的3个月内则一直处于低于正常的水平。结论：CD40L高表达与GVHD的发生相关，提示CD40-CD40L共刺激途径在GVHD的发生中可能起着重要作用。     

Epitope‐dependent synergism and antagonism between CD40 antibodies and soluble CD40 ligand for the regulation of CD23 expression and IgE synthesis in human B cells

BACKGROUND: The induction of IgE synthesis in naive B cells requires two T-cell-derived signals: one delivered through CD40 and the other via interleukin-4 (IL-4). The natural counterstructure to CD40 is the CD40 ligand (CD40L). We have asked about the interplay between CD40L and CD40 mAb that recognize distinct epitopes in delivering signals for regulating IL-4-dependent IgE synthesis and the expression of CD23, the low-affinity IgE receptor, in resting B cells. METHODS: After culture of purified human tonsillar B cells with CD40 agonists and IL-4, surface CD23 was determined by flow cytometric analysis. CD23 levels in cell lysates and supernatants were quantified by ELISA, as were those of secreted IgE. RESULTS: With regard to both induction of CD23 and IgE production, soluble CD40L trimer (sCD40LT) showed synergistic interaction with two mAb to CD40 which bind to epitopes located outside the ligand binding site (EA5 and 5C3), but not with a mAb (G28-5) which effectively competes for CD40L binding to CD40. Each of the two noncompeting mAb to CD40 was able to cooperate strongly with sCD40LT in promoting high-level induction of CD23 even in the absence of IL-4, an effect mirrored in the promotion of strong homotypic clustering and high-rate DNA synthesis. G28-5, uniquely, induced a down-regulation in IL-4-induced CD23 expression with time, a change that was accompanied by an increase in the amount of soluble CD23 detected. While the two noncompeting mAb consistently synergized with sCD40LT for the promotion of IL-4-dependent IgE synthesis, sCD40LT and G28-5 (which, by itself, was the most potent of the CD40 mAb at inducing IL-4-dependent IgE production) exhibited mutual antagonism in this regard, the level of which could be quite profound. CONCLUSIONS: This study demonstrates that appropriate targeting of CD40 can modulate IgE synthesis either positively or negatively.     

A soluble form of TRAP (CD40 ligand) is rapidly released after T cell activation

TRAP is a tumor necrosis factor (TNF)-related, 33-kDa type II transmembrane protein almost exclusively expressed on the surface of activated CD4⁺ T lymphocytes. Interaction of TRAP with CD40 on B cells is of paramount importance for immunoglobulin class switching and subsequent synthesis of IgG, IgA or IgE in vivo. We now provide evidence that activated T cells not only express cell membrane-associated TRAP but also a soluble form of TRAP (sTRAP). After generating monoclonal antibodies against TRAP and establishing a TRAP-specific enzyme-linked immunosorbent assay we were able to detect substantial amounts of sTRAP in the supernatants of activated T cells. The onset and rate of sTRAP release was found to parallel the expression of TRAP on the cell surface. sTRAP, an 18-kDa protein, is generated by proteolytic proccessing of full-length TRAP in an intracellular compartment. Starting with methionine 113 of fulllength TRAP, sTRAP lacks the transmembrane region and a part of the extracellular domain but contains the entire TNF-α homology region and can, therefore, bind to CD40. Like other members of the TNF superfamily (e.g. TNF-α, Fas/APO-1 ligand), TRAP thus has the potential to be biologically active not only in a transmembrane form but also as a soluble molecule.     

CD40-CD40 ligand interactions stimulate B cell antigen processing

The interactions between B cell CD40 and T cell CD40 ligand (CD40L) have been shown recently to play an important role in T cell-dependent activation of B cells. Here, we show that the ligation of CD40 stimulates the processing of antigen by B cells. The activation of an antigen-specific T cell hybrid by B cells co-cultured with insect cells expressing recombinant CD40L or with a CD40-specific monoclonal antibody requires less antigen and fewer B cells compared to control cells. The augmentation was observed both for processing initiated by antigen binding to and cross-linking the surface immunoglobulin, and processing of antigen taken up by fluid-phase pinocytosis. CD40 appears to affect a step in the intracellular processing of antigen, as CD40 has no effect on the presentation of an antigenic peptide which does not require processing. In addition, the CD40-induced augmentation of processing is not attributable to the effect of CD40 ligation on the cell surface expression of B7, LFA-1 or CD23. CD40 ligation does not affect the biosynthesis of the class II E^k molecules, and although ligation of CD40 induces B cell proliferation, the augmentation of processing does not require proliferation. The ability of CD40 to stimulate B cell antigen processing has the potential to influence significantly the outcome of antigen-dependent T cell-B cell interactions.     

CD40 ligand is a T cell growth factor

CD40 ligand (CD40L) is a 33-kDa type II membrane glycoprotein induced on T cells upon activation. CD40L has previously been shown to induce proliferation of resting B cells, immunoglobulin (Ig) secretion from B cells cultured with cytokines and cytokine secretion and tumoricidal activity from monocytes. In this report CD40L is shown to be stimulatory for human T cells, inducing CD25 (p55 IL-2R) and CD40L expression on resting peripheral blood T cells, enhanced expression of these molecules and CD69 on CD3-activated cells and secretion of interferon-y, tumor necrosis factor-a and interleukin (IL)-2 from T cells cultured in the presence of a sub-mitogenic concentration of phytohemagglutinin A (PHA). Furthermore, stimulation with CD40L induces proliferation of CD3- or PHA-activated T cells of blood, tonsillar or thymic origin. A similar proliferative response is observed with CD4^? and CD8⁺ T cells and this effect is largely IL-2 independent. A soluble construct of the extracellular domain of the CD40L has similar activity to that of membrane-expressed ligand in the induction of T cell surface antigens and proliferation. The results presented here taken together with the various activities ascribed for CD40L on B cells and monocytes demonstrate that CD40L has pleiotropic biological activity for cells of the hemopoietic lineage.     

Characterization and application of two novel monoclonal antibodies against CD40L: epitope and functional studies on cell membrane CD40L and studies on the origin of soluble serum CD40L

CD40 ligand, a 33-kDa cell membrane molecule, a member of the tumor necrosis factor superfamily, is an important costimulatory molecule during immune response. Here, we report on two functional mouse anti-human CD40L monoclonal antibodies 1B1 and 4F1 characterized by flow cytometry, Western blotting, and competition assay. The antibodies bound to distinct CD40L epitopes and therefore resulted in different bioactivity. Both antibodies could induce CD4+ T-cell alloantigenic hyporesponsiveness ex vivo. The antibodies were matched to develop a two-site enzyme-linked immunosorbent assay (ELISA) for soluble CD40L (sCD40L). Using this ELISA assay, we found major differences between plasma and serum sCD40L levels. Because the count of platelet sharply decreased in aplastic anemia (AA) and idiopathic thrombocytopenic purpura (ITP), we further analyzed the sCD40L concentration in the plasma of AA and ITP patients. The results showed that the sCD40L in serum was much lower than that of healthy subjects. These data demonstrate that platelets seem to be a major contributor to sCD40L, though not the only source of sCD40L in serum.     

Altered CD40 ligand induction in tolerant T lymphocytes

CD40 ligand (CD40L) is a member of the tumor necrosis factor superfamily and is expressed on the surface of activated T lymphocytes. The interaction of CD40L with CD40 on B cells results in B cell activation, immunoglobulin (Ig) secretion and Ig class switching. To study anergy as a mechanism of murine CD4 T cell tolerance, we determined both in vivo and in vitro that CD3-activated anergic cells are deficient in the ability to stimulate B cell proliferation, and that anergic cells are defective for the T cell receptor/CD3-mediated induction of CD40L expression. These results have implications for the recruitment of B cell responses by anergic T cells in vivo.