免疫学概述ppt课件

1、分子免疫学概述,2011.09,The Origin of Immune Concept,The term “Immunity” = Latin word “Immunitas” = Protection from legal prosecution (Roman senators) Biological definition = Protection from infectious diseases 2.The concept of immunity = existed in ancient Greek & Chinese = the experienced view,“天花”又名痘疮,十六

2、世纪下半叶（明代隆庆年间1567-1572）正式发明了人痘接种术，十七世纪普遍推广。,The medical view of immunity = Edward Jenner (1796) Observation = Milkmaids generally get No Smallpox Hypothesis = Pus from vaccinia (cowpox) = Protect milkmaids from smallpox Test = Inoculate materials from cowpox pus = Protect a young boy from smallpox (P

3、rotective immunity),The vaccination against smallpox,Exudate from a cowpox pustule on the hand of milkmaid Sarah Nelmes was inserted into scratches on the arms of James Phipps, May 14, 1796.,1796年，英国人Edward Jenner发明牛痘苗预防天花（cowpox vaccine）。,Edward Jenner,Eradication of smallpox,4.The concept of “Immu

4、nity” developed gradually over time through many scientific findings: = Robert Koch (1905 Nobel Laureate) = Infectious diseases caused by microorganisms = Louis Pasteur = Vaccines against cholera & rabies = These clinical successes = The search of underlying mechanism of “Protection of Infectious Di

5、seases”,研制出多种减毒疫苗（attenuated vaccine）,用于预防鸡霍乱,炭疽杆菌,狂犬病等疾病。,Louis Pasteur,1880年，鸡霍乱弧菌减毒疫苗,Vaccines for common infectious diseases,b型流感嗜血杆菌,破伤风,百日咳,风疹,腮腺炎,麻疹,脊髓灰质炎,乙肝,白喉,Still no effective vaccines for many infectious microbes, e.g., HCV, HIV, Dengue virus.etc,细胞免疫和体液免疫学派的形成： (19世纪后叶-20世纪中叶) 免疫学重大学说和理

6、论：克隆选择学说(1957)；免疫网络学说(1974) 对免疫系统的全面认识：发现各种免疫器官及免疫细胞,Descriptive Science” = “Experimental Science”,(1) 细胞免疫学说 (cellular immunity),Neutrophil,梅契尼可夫,1880s- Metchnikoff discovered phagocytic cells that ingest microbes and particles,cells conferred immunity,免疫应答机制的研究:,1. The Discovery of antibody functi

7、ons in 1897 2. The Nobel Laureate in Medicine 1908,Adopted from Nature Immunology, July 2008,liquid of blood conferred immunity,发现抗体能清除各种病原微生物或者能中和细菌毒素。,(2) 体液免疫学说 (humoral immunity),Paul Ehrlich: One of the fathers of humoral adaptive immunity,Q: Which confers immunity cells or serum? A: Both cells

8、 and serum contribute to immunity!,MacFarlane Burnet （1899-1985）,克隆选择学说 clonal selection theory,体内事先就存有能识别各种抗原的细胞克隆(clone)，每一细胞表面均有对特定抗原的受体，能与相应抗原结合而识别它们。抗原的作用在于选择与其相应的细胞克隆与其受体结合后，引起细胞的增殖分化，产生免疫应答，产生大量抗体（即免疫球蛋白）。,抗体形成理论 -克隆选择学说,体内存在无数抗原特异性淋巴细胞克隆 胚胎期与自身成分反应的淋巴细胞被“禁忌”形成耐受 出生后淋巴细胞遇到相应抗原发生特异应答，并形成记忆 禁忌细

9、胞突变可导致自身免疫,Advances in technology (e.g., Cell culture, Monoclonal Ab, Flow cytometry, Genetic engineeringetc) have facilitated our understanding of the immune system and its functions. “,(1)免疫学理论研究 抗体多样性和特异性的遗传学基础 T细胞抗原受体的基因克隆 免疫遗传学和MHC限制性的发现 细胞因子及其受体 信号转导的研究 危险信号学说,(2)免疫学应用研究： 基因工程疫苗 基因工程制备重组细胞因子 免

10、疫细胞治疗 治疗性抗体,免疫（immunity) 传统概念指免除疫病、免除感染，指机体抗感染的防御能力。 现代概念指机体对“自己”或“非己”的识别并排除“非己”的功能。,免疫的基本功能,免疫系统 (immune system)：机体执行免疫功能的组织、器官、细胞和分子构成免疫系统。,The four kinds of pathogens that cause human disease,常见的病原微生物,Overview of immune responses,固有免疫 （innate immunity） 是机体抵御病原微生物入侵的第一道防线，并启动和参与适应性免疫应答。 天然免疫（natur

11、al immunity)或非特异性免疫(nonspecific immunity)，是个体出生时就具有的免疫力，通过遗传获得，是生物在长期进化过程中逐渐形成的，其针对外来异物的范围广，反应迅速，其应答模式和强度不因与病原微生物的反复接触而改变。,固有免疫系统的组成,屏障 细胞 分子,皮肤黏膜屏障：物理、化学、微生物 血-脑屏障、血-胸腺屏障 血-胎屏障、气-血屏障,巨噬细胞、中性粒细胞、树突状细胞、T 细胞、NK细胞、NKT细胞、B1细胞、肥大细胞、嗜碱性粒细胞和嗜酸性粒细胞等。,抗菌肽、溶菌酶、急性期蛋白、补体、细胞因子和黏附分子、,Epithelial barriers prevent t

12、he entry of microbes,固有免疫细胞,Phagocyte NK ILLs（固有样淋巴细胞） DC MC Basophil Eosinophil, T细胞 NKT细胞 B1细胞,Monocyte-macrophage Neutrophil,肺部巨噬细胞吞噬大肠杆菌,Phagocytosis by innate immunity,固有性免疫分子,指体表分泌液以及血浆和其它体液中能够识别或攻击病原体的可溶性分子。,抗菌肽 antimicrobial peptides 溶菌酶 lysozyme 急性期蛋白(acute phase proteins, APP) 脂多糖结合蛋白（LBP）

13、 血清淀粉样蛋白（SAP） 甘露糖结合蛋白（MBP） C反应蛋白等（CRP） 补体 细胞因子和黏附分子,Complement activation pathways,Elie Mechnikoff:The Pioneer of Innate Immunity,1. The Discovery of Phagocytes & Phagocytosis 2. The Nobel Laureate in Medicine 1908,Adopted from Nature Immunology, July 2008,The development of modern Immunology in 20t

14、h century mainly centers on understanding the Adaptive Immune System.,Charles A. Janeway, M.D. Yale Univ.,The “Renaissance” of innate immunity,In 1989, Janeway = Immune recognition of microbes = Detection of conserved molecular patterns, referred to PAMPs (Pathogen-Associated Molecular Patterns) wit

15、h features: 1. Invariant among a given class of microbes. 2. Have essential roles in microbial physiology. 3. Recognized by receptors of the innate immune system, called PRRs (Pattern-Recognition Receptors). 4. Innate immunity regulates adaptive immunity,Julie A. Hoffmann, Ph.D. Strasbourg, France,T

16、he “Renaissance” of innate immunity,In 1996, Hoffmanns group Toll functions as a PRR in Drosophila,Key concepts in innate immunity,1. The innate immune system mainly recognizes common structures shared by classes of microbes, = Pathogen Associated Molecular Patterns (PAMPs), e.g., LPS, Peptidoglycan

17、, Microbial DNA & RNA. 2. Host receptors that recognize PAMPs are called Pattern- Recognition Receptors (PRRs), which are encoded in “Germline” DNA= limited Diversity. 3. Innate immunity not only provide the first line of defenses but link to the program of adaptive immunity. 4. PRRs may also recogn

18、ize components from injured or dead host cells = Autoimmune diseases,Pathogen-AssociatedMolecularPatterns(PAMP),是病原微生物（尤其是原核生物）表面存在一些人体所没有的，但可为许多相关微生物所共享、结构恒定、进化保守的分子结构。,损伤相关分子模式 （damage-associated molecular patterns，DAMPs）,机体自身细胞所释放的内源性分子，即内源性危险信号，来源于受损或坏死组织和某些激活的免疫细胞。主要有HMGB1、热体克蛋白等。,PAMP vs DAMP,

19、Sterile inflammation,conserved microbial motifs VS non-microbial signals,Locations of Different PRRs,Body fluids -Soluble PRRs Cellular PRRs - Cell surface - Endosomes - Cytosol,Toll-like Receptors,MyD88-Dependent and independent Signaling,NLRs are cytoplasmic bacterial sensors that activate inflamm

20、asomes,1,Viral Pattern Recognition Receptors: Signaling and Consequences,Interaction between innate and& adaptive immunity,1. Innate immunity = Ag presentation (by Dendritic cells) 2. Adaptive immunity = Ag recognition (by T & B lymphocytes),适应性免疫 （adaptive immunity）,是机体获得性、抗原特异性、抵抗病原微生物感染的高效防御机制。 获

21、得性免疫（acquired immunity)或特异性免疫(specific immunity)，是个体出生后，在环境中受抗原刺激所产生的免疫力，针对特定抗原，有特异性、多样性、记忆性和耐受性。 1) 特异性，对某个特定的异物性抗原能引起特异性免疫应答；指抗原特异性。 2) 多样性，机体可针对环境中多种多样的抗原，分别建立起不同的特异性免疫应答；多样性是特异性产生的基础。 3) 记忆性，当异物抗原再次入侵时，可产生快而强的再次免疫应答效应；记忆性淋巴细胞。4) 耐受性，正常情况下，免疫系统对自身成分有保护性的免疫耐受；,抗原决定簇Antigenic determinant，AD,抗原分子表面具

22、有特殊立体构型和免疫活性的化学基团称为抗原决定簇或抗原决定基。由于抗原决定簇通常位于抗原分子表面，因而又称为抗原表位(epitope)。 抗原决定簇抗原决定基 抗原表位 抗原决定簇决定抗原的特异性，即决定抗原与抗体发生特异性结合的能力（实际是抗原决定簇与抗体的结合）。,AD的数目、性质和空间构象决定抗原特异性 抗原以AD与相应抗原受体及抗体特异性结合,APC加工处理的抗原种类: 外源性抗原(exogenous antigen): 通过吞噬或吞饮等作用被APC从细胞外摄入的抗原，以抗原肽-MHC I I类分子复合物形式提呈给CD4+T细胞 。 内源性抗原(endogenous antigen):

23、 细胞内合成的抗原，以抗原肽-MHC I类分子复合物形式提呈给CD8+T细胞 。,外源性抗原加工，处理及提呈,APC 摄取的外源性抗原在内体中降解成肽，与 MHC类分子(在内质网合成) 结合后表达于细胞表面。外源性抗原加工中需要 Ii 链和 HLA-DM 分子的参与。Ii 链 与 MHC类分子的转运有关，并通过 CLIP 封闭 MHC类分子的肽结合部位，阻止 MHC-类分子在内质网中与内源性抗原肽结合。HLA-DM 分子促使 CLIP 从 MHC类分子肽结合区解离，有利抗原肽与 MHC类分子结合。,内源性抗原加工，处理及提呈,内源性抗原经蛋白酶体降解成肽，通过抗原加工相关转运体(TAP1、TA

24、P2)转运进入内质网，与 MHC类分子(在内质网合成)结合成肽-MHCI类复合物，通过高尔基体表达于细胞表面。 TAP是内质网上的异源性二聚体，由TAP-1及TAP-2基因编码胞浆中蛋白酶体（proteasomes, 核心成分为低分子量多肽LMP,细胞被病毒感染后出现的病毒蛋白，基因突变后产生的肿瘤抗原,THE ADAPTIVE IMMUNE RESPONSE,Antibody-Mediated Immunity (AMI) Involves B lymphocytes, plasma cells and antibodies Humoral immunity Name derives fro

25、m antibodies found in body fluids (humors - old medical term) Cell-Mediated Immunity (CMI) Involves T lymphocytes, antigen-presenting cells and MHC (major histocompatibility complex) molecules Cellular immunity,Types of adaptive immunity,1. Humoral immunity = Molecules in body fluid, e.g. Antibody (

26、Ab) = Key player = B cells = Target extracellular microbes & toxins 2. Cell-mediated immunity = Key player = T cells = regulate other immune cells = Target intracellular microbes, e.g. viruses, bacteria,For innate immunity, it also includes Humoral & Cellular components for immune defense,1、抗原提呈与识别阶

27、段（感应阶段）： 2、活化、增殖、分化阶段（反应阶段）： T细胞活化、增殖分化为效应T细胞； B细胞活化、增殖分化为浆细胞； 部分细胞发育为记忆细胞。 3、效应阶段： 效应T细胞对抗原的清除； 浆细胞分泌抗体清除抗原。,免疫应答的三个阶段,Overview of adaptive immune responses,CELL-MEDIATED IMMUNITY (CMI),Directed against intracellular microorganisms Non-phagocytic cells and phagocytic cells T-lymphocytes (T cells) D

28、ifferentiate into effector cells following antigen presentation by antigen presenting cells (APCs) Functional types of T cells Helper (CD4 T cells) TH1 and TH2 cells Cytotoxic (CD8 T cells),T cells develop in the thymus,TSC,CD4 RTE,TCR,TCR,CD8,CD4,b-selection,Positive selection,Negative selection,Fu

29、nctional maturation,TCR-b rearrangement,TCR-a rearrangement,CD8 RTE,Development of Thymocytes,Double negative,Double positive,Single positive,T cells undergo further differentiation in secondary lymphoid tissues after encounter with antigen,Only a small fraction of naive T cells (mature T cells befo

30、re they encounter antigen) survives the positive and negative selection, and leaves the thymus. Mature naive T cells can re-circulate between blood and lymphoid tissues for many years (in contrast to B cells, which have shorter life span). In secondary lymphoid tissues, T cells accumulate in T cell

31、areas, where they become activated by their specific antigens. Encounter with antigen induces the final stage of T cell development: their differentiation into effector T cells. Some effector T cells stay in the lymphoid tissues (CD4-TH2 cells), while others migrate to site of infection (CD8 and CD4

32、-TH1 cells).,T细胞受体复合物 由TCR和CD3组成。前者识别和结合抗原肽, 后者将TCR获得的抗原信号传递至细胞内。,T细胞对抗原的识别,APC,T细胞,T细胞活化的双信号刺激 第一信号：TCR对MHCII抗原肽复合物的识别，CD3分子将第一信号传递到细胞内。 第二信号：CD28识别专职APC上的B7分子,又称协同刺激信号。,Effector T cells,In contrast to terminally differentiated B cells (plasma cells), there are several types of terminally different

33、iated effector T cells. CD8 T cells Cytotoxic T cells (recognize MHC class I molecules) CD4 T cells,TH1 helper cells (activate macrophages) TH2 helper cells (induce differentiation of B cells into plasma cells and production of antibodies),Activation (cytokines),(recognize MHC II molecules),The immu

34、ne system is maintained in a carefully regulated balance between the two polarised control arms, Th1 (cellular immunity) and Th2 (humoral immunity).,In disease states the balance is skewed. multiple sclerosis, rheumatoid arthritis and type I diabetes, have a Th1 bias, whereas cancer patients have a

35、Th2 bias.,Th1 and Th2 Cells Do not Represent All CD4+ Cells,More T helper subsets,Th3: TGF-producing CD4 T cells Tr1: IL-10-producing CD4 T cells Th9: IL-9-producing CD4 T cells Tfh: follicular helper T cells, located in the follicular regions of lymph nodes and spleen,follicular Th1/Th2/Th17 cells,

36、ANTIBODY-MEDIATED (HUMORAL) IMMUNITY,Directed against extracellular microorganisms and toxins B-lymphocytes (B cells) Differentiate into plasma cells which produce antibodies Function as antigen-presenting cells (APCs) Classification of Antibodies (Immunoglobulins) Immunoglobulin M (IgM) Immunoglobu

37、lin G (IgG) Immunoglobulin A (IgA) Immunoglobulin D (IgD) Immunoglobulin E (IgE),抗体的功能 V区的功能 识别并特异性结合抗原 单体（IgG, IgE) 2价 二聚体(分泌型IgA) 4价 五聚体(IgM) 10价 中和效应 中和毒素和病毒 与Ag结合 促吞噬细胞吞噬,抗体的结合价,实际意义,C区的功能 1.激活补体系统 Ab(IgM、IgG) + Ag C1q 补体经典途径 IgG4、IgA和 IgE的凝聚物 补体旁路途径 2.介导免疫细胞活性 (1)调理作用（opsonization）：IgG + 抗原(颗粒性

38、) FcR（单核、巨噬细胞及中性粒细胞） 促吞噬细胞吞噬； (2)ADCC：IgG + 抗原(靶细胞) Fc R（NK 细胞） 杀伤靶细胞； (3)介导超敏反应：型、型和型超敏反应。 3.穿越胎盘和粘膜,Antibody-Dependent Cellular Cytotoxicity (ADCC),Th2与B细胞的相互作用，获得第二信号：协同刺激信号,CD40-CD40L,活化的Th2细胞分泌细胞因子及表达CD40L，辅助B细胞活化,第二信号（Th细胞信号） 有二种方式 （1）Th细胞-B细胞间接触作用：CD40L-CD40等 （2）Th细胞分泌细胞因子：IL-4、5、6等,胸腺依赖性抗原（T

39、D-Ag）,Specificity, Memory, and Homeostasis of Adaptive Immunity,体液免疫应答一般规律,多克隆抗体(polyclonal antibody，PcAb )：采用传统的免疫方法，将抗原物质经不同的途径进入动物体内，经数次免疫后采取动物血液，分离出血清，由此获得的抗血清即为多克隆抗体。用天然的抗原物质免疫动物，刺激多个B细胞克隆所获得的免疫血清（含多种特异性抗体）。 单克隆抗体(Monoclonal Antibody，McAb):由一个B细胞分化增殖的子代细胞产生的针对单一抗原决定簇的抗体，称单克隆抗体。 由一个B细胞克隆产生。 识别一种

40、抗原表位。 高度均一（结构、特异性）。 杂交瘤技术制备。 基因工程抗体：利用基因工程技术来制备的抗体分子称为基因工程抗体，是分子水平的抗体。,US和EU所批准的治疗性抗体,鼠源性单克隆抗体将逐渐被人源化抗体所替代：鼠源性单克隆抗体与人补体成分结合能力低，CDC作用相应较弱，对肿瘤细胞的杀伤能力较弱；它与NK等免疫细胞表面Fc受体亲和力弱，介导的 ADCC作用较弱；鼠源抗体在人血循环中的半衰期短，它发挥ADCC与CDC作用的时间较短；鼠单克隆抗体具有免疫原性，宿主易产生抗抗体引起过敏反应。,抗体人源化改造及人源抗体制备,人-鼠嵌合抗体：应用基因工程技术将小鼠单克隆抗体的恒定区用人源抗体恒定区代替

41、而拼接成嵌合抗体。 改型抗体如CDR移植、SDR移植：用鼠单克隆抗体的CDR、SDR移植到人源抗体可变区，替代人源抗体CDR、SDR。 表面氨基酸残基人源化,抗体人源化的主要技术,macrophage,Activated T cell,a,A,D,P56 B C58,B,C,NH2,COOH,IL-2,Cytockines are low-molecular-weight regulatory proteins or glycoproteins secreted by white blood cells and various cells (vascular endothelial cell, epidermic cell and fibroblast ) in body in response to a number of stimuli.,Cytokine,Biological effects,Cytokine imbalance during inflammation,细胞因子的研究热点 1、新细胞因子的基因克隆化 2、细胞因子受体的基因克隆化 3、细胞因子信号转导机制 4、新一代细胞因子：高活性，多功能，低毒副作用，长半衰期，