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超抗原由某些细菌、病毒、支原体和寄生虫产生，其中金黄色葡萄球菌肠毒素(SE)中SEB具有代表性；已知超抗原(SAg)可大量激活人和小鼠T细胞(CD4^ 和CD8^ )和抗原递呈细胞(APC)，并诱导IL-1、IL-2、IL-6、TNF、IFN-γ等Th-1细胞因子，乃至免疫无反应、细胞凋亡和免疫抑制；超抗原SEB诱导CD8^ T细胞成为细胞毒性T细胞，启动NK细胞的细胞因子产生，有研究发现，SEB具有双相激活作用，高剂量诱导迅速，低剂量诱导长期而长期的激活状态。 相似文献
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为研究超抗原（SAg)在禽类诱导的免疫机理和进一步揭示MDV（马立克氏病病毒）感染的免疫学规律，采用NO－释放法，设计用雏鸡骨髓巨噬细胞为靶细胞检测1日龄雏鸡接种超抗原SEB和MDV后脾与胸腺淋巴细胞IFN－γ体外诱生的动态变化。结果发现，超抗原SEB（SAG－SEB）可提高脾与胸腺淋巴细胞IFN－γ体外诱生水平，其中，高剂量（1ng/只）引起短时加强后下降，而低剂量（0.01ng)则出现缓升缓降现象，而MDV接种则抑制脾与胸腺淋巴细胞IFN－γ体外诱生，SAg-SEB能增强雏鸡细胞免疫，主要表现于接种初期（1－10dPI)，而MDV却在接种后1－25d间降低细胞免疫，说明超抗原SEB和MDV虽然均可引起鸡T细胞增殖，但对鸡免疫细胞IFN－γ的体外诱生作用不同。 相似文献
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B细胞受抗原的刺激而产生抗体，是一个相当复杂的过程，这也说明B细胞所处的微环境的特殊性。B细胞产生抗体需要T细胞和巨噬细胞的帮助，这一复杂过程大致可分为三个阶段。1．3．1．l第一阶段抗原受巨噬细胞处理加工后，通过限制性方式呈献于TH，即要求巨噬细胞和TH二者的主要组织相容性复合体（majorhistocomPatibilitv。。mplex，MHC）的I类分子必须同型。这样，抗原的载体就同T。进行限制性结合。此时，巨噬细胞产生a因子，T。产生p和7因子，这些因子在第二阶段发挥其激活B细胞的辅助作用。1．3．1．2第M阶段是激活B细胞使之发展… 相似文献
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李治力 《河南畜牧兽医(综合版)》2002,23(8):16-16
南京农业大学李祥瑞博士研制成功的一种新的免疫增强剂———白细胞介素－２（IL－２），它是由多个氨基酸组成的糖蛋白。IL－２具有促进体液免疫和细胞免疫的双重功能，其主要生物学活性有以下几个方面：１直接作用于B细胞促进其增殖、活化、产生抗体。２能显著促进T细胞活化、增殖，并增加杀伤性T细胞的作用。３刺激自然杀伤细胞，并增强其溶细胞活性。４可诱导杀伤性T细胞、淋巴因子激活的杀伤细胞等杀伤细胞的分化和效应，并诱导这些杀伤细胞产生干扰素、肿瘤坏死因子等细胞因子。５能活化巨噬细胞，增加吞噬病原体功能。大量试验证… 相似文献
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为研究超抗原(SAg)在禽类诱导的免疫机理和进一步揭示MDV(马立克氏病病毒)感染的免疫学规律,采用NO-释放法,设计用雏鸡骨髓巨噬细胞为靶细胞检测1日龄雏鸡接种超抗原SEB和MDV后脾与胸腺淋巴细胞IFN-γ体外诱生的动态变化.结果发现,超抗原SEB(SAG-SEB)可提高脾与胸腺淋巴细胞IFN-γ体外诱生水平,其中,高剂量(1 ng/只)引起短时加强后下降,而低剂量(0.01 ng)则出现缓升缓降现象;而MDV接种则抑制脾与胸腺淋巴细胞IFN-γ体外诱生; SAg-SEB能增强雏鸡细胞免疫,主要表现于接种初期(1-10 d PI),而MDV却在接种后1-25 d间降低细胞免疫;说明超抗原SEB和MDV虽然均可引起鸡T细胞增殖,但对鸡免疫细胞IFN-γ的体外诱生作用不同. 相似文献
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抗原经动物的口腔、粘膜或注射等途径进入动物体内，抗原在动物的体内，经过一系列免疫应答产生抗体。抗体的产生，首先抗原在机体内通过透导，在透导的过程中，根据透导时间的长短，决定抗体——IgG或IgM的产生。抗原在体内透导时间长短，它决定于抗原的性质和动物机体的反应程度，在体内透导的时间越长，产生IgG的可能性就越大(IgG在体内的产生晚于IgM)，再次反应需借助T细胞和B细胞的作用，与依赖性抗体FC(成熟的B细胞)结合，这种结合武装的白细胞，产生一种相应抗病原微生物的作用。 相似文献
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美研究人员报道 ,重组的全酵母疫苗能够激活树突状细胞 ( DC)并诱导保护性细胞免疫。研究人员在测试表达肿瘤和 HIV-1抗原的重组酿酒酵母 ( Saccharomyces cerevisiae)的免疫原性时发现 ,在不存在佐剂的情况下 ,用这种重组酵母免疫的小鼠能产生很强的包括肿瘤保护的抗原特异性 CTL反应 ,而且这种酵母还能刺激 DC的成熟和 IL-1 2产生 ,从而有效激发 MHC-1和 MHC-2限制的抗原特异性 T细胞反应。这项研究表明 ,重组酵母载体疫苗在诱导对多种传染病和肿瘤的有效细胞免疫方面也许有更强的作用重组酵母疫苗诱导细胞介导的保护性免疫@郭志… 相似文献
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B淋巴细胞的祖细胞存在于胎肝（胚胎小鼠14d或胎儿8－9周）的造血细胞岛（islandsofhaemopoieticcells）中，此后B淋巴细胞的产生和分化场所逐渐被骨髓所代替。B细胞（即B淋巴细胞）是淋巴样干细胞在鸟类法氏囊和哺乳类动物的骨髓中分化成熟而来，成熟的B细胞主要定居于淋巴结皮质浅层的淋巴小结和脾脏的红髓和白髓的淋巴小结内。成熟的B细胞经抗原或其它配体（如抗smIg）刺激活化后，进人克隆增殖状态，最后分化成熟为分泌抗体细胞（浆细胞），浆细胞能合成和分泌免疫球蛋白，主要执行机体的体液免疫（hu－moralimmunity）。在B细胞分… 相似文献
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Joo Youn Park Lawrence K. Fox Keun Seok Seo Mark A. McGuire Yong Ho Park Fred R. Rurangirwa William M. Sischo Gregory A. Bohach 《Veterinary microbiology》2011,147(1-2):149-154
The coagulase-negative staphylococci (CNS) are the most prevalent mastitis pathogen group yet their virulence characteristics have not been well described. We investigated the presence of 19 classical and newly described staphylococcal superantigen (SAg) genes in CNS isolates from bovine intramammary infections (IMI). A total of 263 CNS representing 11 different Staphylococcus spp. were examined, and 31.2% (n = 82) of CNS isolates had one or more SAg genes; there were 21 different SAg gene combinations. The most prevalent combination of SAg genes (seb, seln and selq; n = 45) was found in S. chromogenes, S. xylosus, S. haemolyticus, S. sciuri subsp. carnaticus, S. simulans and S. succinus. The genes for SAgs appear to be widely distributed amongst CNS isolated from bovine IMI. 相似文献
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多肽表位作为抗原的重要组成成分,可以被宿主免疫系统B细胞产生的抗体（Ig）和T细胞受体（TCR）识别,从而诱导机体产生免疫保护作用。传统的研究方法如交叠肽合成等费时费力,极大地限制了多肽表位的研究。随着生物信息学、高通量测序、CRISPR/Cas9、质谱（MS）等技术出现以及TAP非依赖型蛋白加工机制的不断阐述,使表位的研究得到不断完善。作者介绍了最新的多肽表位研究方法,包括利用计算机对B细胞和T细胞表位的预测、基于MHC与抗原肽结构作用为基础的方法、结合高通量测序技术的表位筛选方法、结合新型基因编辑技术的表位筛选方法、TAP非依赖性T细胞表位的最新研究等,并对今后多肽表位研究的发展进行了展望。 相似文献
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As an important component of the antigen, peptide epitopes can be recognized by T cell receptor (TCR) and antibodies which induced protective immunity by the host immune system. Traditional research methods, such as overlapping peptide synthesis is long time-consuming which greatly limits the study of epitopes. With the development of bioinformatics, high-throughput sequencing, CRISPR/Cas9 technology, MS and other technologies and explaining the processing mechanism of TAP-dificient protein constantly, the research for epitopes is being perfect continually. In this article, some new methods to study epitopes were introduced, including computer prediction of B cell or T cell epitopes, identification of epitopes based on the structure and interaction of MHC and antigenic peptides, screening epitopes by means of high throughput sequencing, screening epitopes by means of newly genome editing, the up-to-date research in TAP-deficient T cell epitopes, etc. Finally,future prospect for research direction of peptides was further forecasted. 相似文献
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FIV/HIV infections are associated with an early robust humoral and cellular anti-viral immune response followed by a progressive immune suppression that eventually results in AIDS. Several mechanisms responsible for this immune dysfunction have been proposed including cytokine dysregulation, immunologic anergy and apoptosis, and inappropriate activation of immune regulatory cells. Studies on FIV infection provide evidence for all three. Cytokine alterations include decreases in IL2 and IL12 production and increases in IFNγ and IL10 in FIV+ cats compared to normal cats. The elevated IL10:IL12 ratio is associated with the inability of FIV+ cats to mount a successful immune response to secondary pathogens. Additionally, chronic antigenic (FIV) stimulation results in an increase in the percent of activated T cells expressing B7 and CTLA4 co-stimulatory molecules in infected cats. The expression of these molecules is associated with T cells that are undergoing apoptosis in the lymph nodes. As ligation of CTLA4 by B7 transduces a signal for induction of anergy, one can speculate that the activated T cells are capable of T cell–T cell interactions resulting in anergy and apoptosis. The inability of CD4+ cells from FIV+ cats to produce IL2 in response to recall antigens and the gradual loss of CD4+ cell numbers could be due to B7–CTLA4 interactions. The chronic antigenemia may also lead to activation of CD4+CD25+ T regulatory cells. Treg cells from FIV+ cats are chronically activated and inhibit the mitogen-induced proliferative response of CD4+CD25− by down-regulating IL2 production. Although Treg cell activation can be antigen-specific, the suppressor function is not, and thus activated Treg cells would suppress responses to secondary pathogens as well as to FIV. Concomitant with the well-known virus-induced immune suppression is a progressive immune hyper-activation. Evidence for immune hyper-activation includes polyclonal B cell responses, gradual replacement of naïve CD4+ and CD8+ T cell phenotypes with activation phenotypes (CD62L−, B7+, CTLA4+), and the chronic activation of CD4+CD25+ Treg cells. Thus lentivirus infections lead to severe immune dysregulation manifested as both chronic immune suppression and chronic immune activation. FIV infection of cats provides a number of advantages over other lentivirus infections as a model to study this immune dysregulation. It is a natural infection that has existed in balance with the cat's immune system for thousands of years. As such, the natural history and pathogenesis provides an excellent model to study the long-term relationships between AIDS lentivirus and host immune system function/dysregulation. 相似文献
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It is well established that T cells cannot be activated by antigen alone but only if antigen is presented in context with I region associated (Ia) determinants. As a matter of fact, antigen-presenting cells or accessory cells, which are obligatory for the induction of any type of immune response, all share the same major characteristic of Ia expression. Thus, there seems to be a direct correlation between accessory cell function and Ia expression. Originally, Ia determinants were only detected on a few cell types, B cells and macrophages being the first. However, during the course of time, more and more cells were found to be Ia positive (Ia +) and it is possible that most cells can express Ia, if appropriately induced. The regulation of Ia expression has been best studied in macrophages, where it has been found that positive induction elements include phagocytosis and gamma-interferon, while prostaglandin E and alpha-fetoprotein tend to down-regulate the expression of Ia. The regulation of Ia expression on accessory cells is thus an integrated part of immune regulation. It is highly likely, although not yet directly proven, that the Ia molecules are the products of the immune response (Ir) genes located within the major histocompatibility complex. They may even be the mediators of the Ir genes which determine whether an immune response can take place at all and/or the extent of the response. Recently, it has been shown that not all Ia + cells are able to activate every known T cell function.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Yong Ho Park Sang Un Lee Witold A. Ferens Sparrow Samuels William C. Davis Lawrence K. Fox Jong Sam Ahn Keun Seok Seo Byoung Sun Chang Sun Young Hwang Gregory A. Bohach 《Journal of veterinary science (Suw?n-si, Korea)》2006,7(3):233-239
We previously demonstrated that stimulation of bovine peripheral blood mononuclear cells (PBMCs) with staphylococcal enterotoxin C (SEC), led to an inversion of the CD4+:CD8+ T cell ratio and generation of an atypical CD8+ T cell subpopulation expressing CD26. In the present study, we examined T cell apoptosis and proliferation profiles of PBMC subpopulations in cultures stimulated with SEC. Unlike when stimulated with concanavalin A, nucleic acid synthesis in bovine PBMC cultures stimulated with SEC was low during the first four days but increased greatly on day 5. In contrast, nucleic acid synthesis in human PBMC cultures stimulated with SEC increased continuously. To investigate the mechanism of delayed bovine T cell proliferation, various cell phenotypes were monitored. The inversion of the bovine CD4+:CD8+ T cell ratio in PBMC cultures stimulated by SEC was associated with higher proliferation and lower apoptosis of CD8+ T cells compared to CD4+ T cells. The mRNA levels for interleukin (IL)-4 and IL-13 were sustained over 4 days but IL-12 mRNA levels dropped to background on day 2. These data suggest that SEC induces a prolonged Th-2-biased microenvironment, and together with the inversion of the bovine CD4+:CD8+ T cell ratios in bovine PBMC cultures with SEC, may in part explain the inability of the mammary immune system to establish an effective response to Staphylococcus aureus infections. 相似文献
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应用ＥＬＩＳＰＯＴ试验测定重组卡介苗诱导的Ｔ细胞应答 总被引：7，自引：1，他引：6
应用免疫磁性分离技术去除免疫小鼠脾脏细胞中ＣＤ４^ 或ＣＤ8^ Ｔ细胞后，在酶免疫斑点试验中证实表达大肠杆菌ＭalE蛋白的重组卡介苗（rBCG.MalE)诱导的Ｔ细胞应答是ＣＤ４^ t细胞依赖的对MalE、PPD持异Ｔ细胞应答的动态分析结果表明，，rBCG.MalE、ＢＣＧ诱导的特异ＣＤ４^ T细胞应答存在Ｔh1/Th2平衡转换现象，即起始阶段为Ｔh1应答，一段时间后出现Ｔh2应答，并逐步形成Ｔh1/Th２混合应答。这些结果，分为枝杆菌Ｔ细胞应答规律提供了新的认识，同时，亦表明ＢＣＧ是优良的外源抗原表达与运送载体。 相似文献
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体外表达猪瘟病毒(CFSV)T、B细胞表位,并对表达产物的免疫原性进行分析.人工合成CFSV的多个T、B细胞表位及表位之间的连接linker基因,并将该基因插入pGEX-6P-1表达载体,经酶切和测序鉴定获得重组阳性克隆,成功构建了CFSV复合多表位抗原基因的原核表达质粒pGEX-BT500,转化E.coli BL21,IPTG诱导表达,纯化表达产物并免疫兔.结果:通过IPTG诱导目的基因可高效表达,SDS-PAGE结果表明,以终浓度为0.9 mmol· L-1的IPTG进行诱导,7h后表达量最高,产物分泌表达,相对分子质量约43 ku,表达产量约占菌体总蛋白的30％.Western blotting检测表明,表达的融合蛋白能与猪瘟阳性血清发生特异性反应;兔攻毒试验表明所免疫表达产物可保护(根据发热反应评价)兔.结果表明表达获得的产物具有良好的反应原性,这为应用该融合蛋白制备CSFV免疫血清学诊断试剂和多表位疫苗研究奠定了基础. 相似文献
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Glass EJ 《Research in veterinary science》2001,70(1):71-75
The tick-borne protozoan parasite, Theileria annulata, causes an overwhelming disease in Friesian cattle, imported to improve productivity, in a large area of the world. The parasite invades bovine macrophages and induces aberrant changes which seem pivotal in triggering disease in na?ve susceptible animals: parasite infected cells acquire dendritic cell features and over-activate CD4+ and CD8+ T cells. Elevated levels of interferon-gamma (IFN-gamma) are induced and B cells are developmentally arrested in the light zone of germinal centres. Infected macrophages are refractory to the effects of IFN-gamma and indeed flourish in its presence. High levels of pro-inflammatory cytokines, as evinced by high acute phase protein responses, probably also play a role in pathology. However, animals can become immune to further challenge. Cellular immune responses involving macrophages, natural killer cells and CD8+ T cells play a major role in recovery and subsequent maintenance of immunity. The main target for immunity appears to be the parasite infected macrophage, as attenuated cell lines can protect and are used as vaccines. Cloned lines selected for low cytokine production protect with no associated pathological reactions. Theileria annulata causes a relatively mild disease in an indigenous breed of cattle, which is associated with lower acute phase protein responses (controlled by macrophage cytokines). Thus the initial host-parasite interactions must determine the balance between immunity and pathogenesis. New generation vaccines to T. annulata should both induce active immunity and suppress pathology. 相似文献