Lymphocyte Dynamics

淋巴细胞动力学

• 批准号: 8336169
• 负责人: William Paul
• 金额: $ 129.17万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8336169
• 关键词: Academy; Accounting; Adjuvant; Antigens; Biological Models; Blastomyces; C-Peptide; CD4 Positive T Lymphocytes; CD8-Positive T-Lymphocytes; CD8B1 gene; Cell Count; Cell Death; Cell Fraction; Cell Proliferation; Cells; Cessation of life; Chronic Phase; Collaborations; Complex; Computational Biology; Data; Dendritic Cells; Effector Cell; Feedback; Frequencies; Genes; Goals; HIV; HIV Infections; Heating; Homeostasis; Human; IL2RA gene; Immune response; Immune system; Immunization; Immunocompetence; Immunology; Individual; Infection; Interleukin-1; Interleukin-15; Interleukin-17; Interleukin-2; Interleukin-7; Knock-out; Laboratories; Lead; Listeria monocytogenes; Lymphocyte; Lymphocyte Count; Lymphocytic choriomeningitis virus; Macaca; Measurement; Measures; Mediating; Memory; Molecular; Mus; Oregon; Pattern; Peptide/MHC Complex; Phenotype; Physiological; Play; Population; Primates; Process; Production; Proliferating; Proteins; Recording of previous events; Regulation; Regulatory T-Lymphocyte; Relative (related person); Role; SIV; Science; Scientist; Self Stimulation; Series; Specificity; Supplementation; T-Cell Depletion; T-Cell Proliferation; T-Cell Receptor; T-Lymphocyte; TNF gene; Time; Transgenic Organisms; Vaccines; Work; antigen challenge; base; cytokine; immune activation; immunogenicity; in vivo; interdisciplinary approach; killings; lymphocyte proliferation; mathematical model; memory CD4 T lymphocyte; precursor cell; professor; receptor; research study; response; tool development

Lymphocyte numbers are regulated both by responses to conventional exogenous antigens and endogenous microflora, by stimulation by self-peptide/MHC complexes and by the action of a series of cytokines. This multifaceted regulation permits individuals to maintain a broad repertoire of lymphocytes of distinctive specificities, allowing responses against a vast array of foreign substances and, at the same time, providing a pattern of memory based on the immunization history of the individual. The study of the process of lymphocyte dynamics that underlies this regulation requires a multidisciplinary approach, aimed both at the molecular underpinnings of the processes through which lymphocytes survive and proliferate and a systemics/ computational biology approach to appreciate the overall mechanisms governing total numbers of lymphocytes of distinct phenotype and distinct specificity. Emphasis has been placed on four aspects of this problem: the priming and expansion of naive CD4 T cells in response to antigen challenge, the dynamics of lymphocyte memory and of memory phenotype cells, the mechanisms underlying CD4 T cell depletion in HIV infection, and the process of homeostatic proliferation and death. Unit scientists have shown that primary responses are highly dependent upon the number of precursor cells that can respond to antigenic challenge. Using both real time PCR and flow cytometric analysis to measure the response when TCR transgenic cells are transferred to intact recipients, it has been shown that the factor of expansion (FE) of the antigen-stimulated CD4 T cells is highly dependent upon the number of specific precursors. In a model system based on responses of T cell receptor transgenic cells specific for a cyctochrome C peptide, when the frequency of precursors in the recipient is 3 or less, FE is 1500, at 300 cells it is 200 and at 30,000 it is 20. Limitation in expansion does not result from a smaller fraction of cells responding but rather, at least in part, from diminished proliferative rates of responding cells. Diminution in FE as number of precursors increase cannot be accounted for by Fas, TNF or IFNg-mediated cell death nor can it be due to limitation in numbers of dendritic cells or in amounts of antigen as increasing either DC number or amount of antigen does not alter the relationship of FE and precursor number. Furthermore, the effect is not altered by supplementation with IL-1, IL-2, IL-7 or IL-15. The relative frequency of regulatory T cells, either derived from the responding cells or from the host, is not altered by precursor frequency and the difference in FE occurs even when responding cells are unable to develop into regulatory T cells. The effect is highly antigen specific in that large numbers of cells of one specificity do not effect the rate of expansion of small numbers of cells of another specificity. The advantage of smaller cell numbers is even greater oif the cells are unresponsive to IL-27, suggesting that lymphocyte expansion is innately independent of precursor number but that effect is tempered by feedback effects of IL-27. In collaboration with Professor Gennady Bocharov of the Russian Academy of Sciences, a mathematical model of the proliferation of these cells has been developed conforms very well to the observed data. In the course of analyzing the control of FE on the part of both nave and memory cells, it was observed that the most potent stimulant of FE was the cytokine IL-1. When expansion of CD4 TCR transgenic T cells in a syngeneic host in response to antigen was measured, it was found that administering IL-1 over a 3 to 5 day period caused a ten fold enhancement in FE when compared to that seen using conventional adjuvants such as LPS. This was equally true for naive and memory cells and was not mediated by other cytokines. The effect could only be partially explained by enhanced proliferation so that greater survival was also implicated. The use of recipients that were IL-1 receptor knockouts and IL-1 receptor-sufficient donors of TCR transgenic T cells showed that IL-1 could act directly on the responding CD4 or CD8 T cells to mediate expansion. The IL-1 receptor antagonist diminished the adjuvant effect of LPS indicating that a substantial portion of the effect of this conventional adjuvant was due to endogenous production of IL-1. Initial analysis of genes activated and suppressed in cells responding to antigen in the presence of LPS suggest avenues for further analysis that may lead to a mechanistic understanding of the IL-1 effect. The very robust effect of IL-1 suggests it may have a role in certain immunization strategies. IL-1 acts directly on CD4 T cells to enhance their differentiation into IL-17 producing cells. However, although IL-1 acts directly on CD8 cells to mediate their expansion, differentiation of CD8 cells requires the action of IL-1 on non T cells. Experiments involving the use weak vaccines, such as heat killed Listeria monocytogenes, the gD2 protein of H. simplex, heat killed Blastomyces or a pneumococcal protein candidate have shown that the magnitude and protective value of these agents is strikingly enhanced when IL-1 is used together with the vaccine to enhance immunogenicity. Memory CD4 T cell proliferation was shown to be quite slow. Specific T cells from mice infected with LCMV divide at a rate of 2% per day. By contrast CD44bright CD25- CD4 T cells divide much more rapidly, at 8 to 10% per day. Furthermore this rapid steady state proliferation of "memory phenotype" CD4 T cells is similar in conventional and germfree mice. Analysis of the repertoire of memory phenotype undergoing proliferation revealed no difference in receptor complexity from that of non-dividing memory phenotype cells. This implies that division is largely stochastic and probably dominantly driven by cytokines rather than by peptide/ MHC complexes, whether of exogenous or endogenous origin. Working with colleagues at the Oregon Regional Primate Center, we have analyzed lymphocyte dynamics in SIV-infected macaques and have obtained evidence for CD4 T cell populations that decay at very distinct rates in the period after their burst-like expansion. Laboratory of Immunology scientists and our colleagues have shown the critical role that aberrant immune activation in lentiviral infection plays in the decay of CD4 T cell number and in the degradation of immunocompetence in SIV-infected macaques and HIV-infected humans. The ongoing activation of the immune system caused directly or indirectly by infection appears to be of particular importance in the loss of potential effector cells during the chronic phase of the infection.

淋巴细胞数通过对常规外源抗原和内源性菌群的反应，通过自肽/MHC复合物刺激以及一系列细胞因子的作用来调节淋巴细胞。这种多方面的调节允许个人维持广泛的特异性淋巴细胞，允许针对各种异物的反应，同时，基于个体的免疫历史提供了记忆模式。该调节基础的淋巴细胞动力学过程的研究需要多学科的方法，这既针对淋巴细胞生存和增殖的过程的分子基础，又是一种系统/计算生物学方法，以欣赏整体机制的总体机制，构成了不同的淋巴结型和不同型的型物型。重点放在了这个问题的四个方面：响应抗原挑战，淋巴细胞记忆和记忆表型细胞的动力学启动和扩展，HIV感染中CD4 T细胞耗竭的基础机制以及稳态增殖和死亡的过程。 单位科学家表明，主要反应高度依赖于可以响应抗原挑战的前体细胞的数量。当将TCR转基因细胞转移到完整的受体时，使用实时PCR和流式细胞仪分析来测量反应，已经表明，抗原刺激的CD4 T细胞的膨胀因子（FE）高度依赖于特定前体的数量。在模型系统中，基于T细胞受体转基因细胞的响应，特异于细胞色素C肽时，当受体中的前体的频率为3或更小时，Fe为1500，在300个细胞时为200个细胞，在30,000时为20。膨胀的限制并不是由于细胞的较小分数而响应，但至少在较小的细胞响应中响应了一个细胞的呈现速率。 Fe的减少，因为FAS，TNF或IFNG介导的细胞死亡无法解释前体的数量增加，这也不能因为树突状细胞数量的限制或抗原量的限制，因为DC数量增加或抗原的数量不会改变Fe和前体数量的关系。此外，补充IL-1，IL-2，IL-7或IL-15不会改变效果。调节性T细胞的相对频率（源自响应细胞或宿主）的相对频率不会因前体频率而改变，即使响应细胞无法发展为调节性T细胞，FE的差异也会发生差异。该作用是高度抗原特异性的，因为一个特异性的大量细胞不会影响另一种特异性的少量细胞的膨胀速率。细胞数较小的优点是细胞对IL-27的反应无反应，这表明淋巴细胞膨胀与前体数独立于前体数，但这种效果受到IL-27的反馈效应的缓解。 与俄罗斯科学院的Gennady Bocharov教授合作，已经开发出这些细胞增殖的数学模型非常符合观察到的数据。 在分析中殿和记忆细胞部分的Fe控制过程中，观察到Fe最有效的刺激剂是细胞因子IL-1。当测量合成宿主中CD4 TCR转基因T细胞的膨胀时，与使用常规辅助剂（如LPS）相比，在3至5天的抗原响应抗原响应抗原时，在3至5天的时间内施用IL-1会增加十倍的增强。对于天真和记忆细胞而言，这同样是正确的，并且不是由其他细胞因子介导的。这种效果只能通过增强的增殖来部分解释，因此也涉及更大的生存。使用IL-1受体敲除和TCR转基因T细胞的IL-1受体充满供体的受体的使用表明，IL-1可以直接作用于反应的CD4或CD8 T细胞上以介导膨胀。 IL-1受体拮抗剂减少了LP的辅助作用，表明该常规辅助剂的很大一部分是由于内源性产生IL-1所致。在LPS存在下对抗原反应的细胞中激活和抑制的基因的初步分析提出了进一步分析的途径，这可能会导致对IL-1效应的机械理解。 IL-1的非常强大的作用表明它可能在某些免疫策略中起作用。 IL-1直接作用于CD4 T细胞，以增强其分化为IL-17产生的细胞。 但是，尽管IL-1直接作用于CD8细胞介导其膨胀，但CD8细胞的分化需要IL-1对非T细胞的作用。 涉及使用弱疫苗的实验，例如热杀死李斯特菌单核细胞增生李斯特氏菌，H。单核细胞增生李斯特菌，热杀死的爆炸性药物或肺炎球菌蛋白候选者的实验表明，当IL-1与疫苗一起使用以增强免疫力的疫苗时，这些药物的幅度和保护价值显着增强。 记忆CD4 T细胞增殖表明非常慢。 来自感染LCMV的小鼠的特异性T细胞以每天2％的速率分裂。 相比之下，CD44Bright CD25- CD4 T细胞以每天8至10％的速度更快地分裂。 此外，在常规小鼠和无毛虫小鼠中，“记忆表型” CD4 T细胞的这种快速稳态增殖相似。对发生增殖的记忆表型曲目的分析表明，受体复杂性与非分散记忆表型细胞的复杂性没有差异。 这意味着分裂在很大程度上是随机的，可能是由细胞因子而不是由肽/ MHC复合物（无论是外源性还是内源性起源）驱动的。 与俄勒冈地区灵长类动物中心的同事合作，我们分析了SIV感染的猕猴中的淋巴细胞动力学，并获得了CD4 T细胞种群的证据，这些CD4 T细胞种群在其突发样膨胀后以非常不同的速度衰减。免疫学科学家和我们的同事的实验室表明，在慢病毒感染中异常的免疫激活在CD4 T细胞数量的衰减中发挥异常，以及在SIV感染的猕猴和受HIV感染的人中的免疫能力降解中。在感染的慢性阶段，由于感染直接或间接引起的免疫系统的持续激活似乎在潜在效应细胞的丧失中特别重要。