Lecture1-免疫學概述.ppt

1、分子免疫學概述,吉林大學畜牧獸醫(yī)學院 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,

2、“天花”又名痘瘡,十六世紀下半葉（明代隆慶年間1567-1572）正式發(fā)明了人痘接種術，十七世紀普遍推廣。,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

3、smallpox (Protective 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，英國人Edward Jenner發(fā)明牛痘苗預防天花（cowpox vaccine）。,Edward Jenner,Eradication of smallpox,4.The conce

4、pt of “Immunity” 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 In

5、fectious Diseases”,研制出多種減毒疫苗（attenuated vaccine）,用于預防雞霍亂,炭疽桿菌,狂犬病等疾病。,Louis Pasteur,1880年，雞霍亂弧菌減毒疫苗,Vaccines for common infectious diseases,b型流感嗜血桿菌,破傷風,百日咳,風疹,腮腺炎,麻疹,脊髓灰質炎,乙肝,白喉,Still no effective vaccines for many infectious microbes, e.g., HCV, HIV, Dengue virus.etc,細胞免疫和體液免疫學派的形成： (19世紀后葉-20世紀中葉

6、) 免疫學重大學說和理論：克隆選擇學說(1957)；免疫網(wǎng)絡學說(1974) 對免疫系統(tǒng)的全面認識：發(fā)現(xiàn)各種免疫器官及免疫細胞,Descriptive Science” = “Experimental Science”,(1) 細胞免疫學說 (cellular immunity),Neutrophil,梅契尼可夫,1880s- Metchnikoff discovered phagocytic cells that ingest microbes and particles,cells conferred immunity,免疫應答機制的研究:,1. The Discovery of anti

7、body functions in 1897 2. The Nobel Laureate in Medicine 1908,Adopted from Nature Immunology, July 2008,liquid of blood conferred immunity,發(fā)現(xiàn)抗體能清除各種病原微生物或者能中和細菌毒素。,(2) 體液免疫學說 (humoral immunity),Paul Ehrlich: One of the fathers of humoral adaptive immunity,Q: Which confers immunity cells or serum? A:

8、 Both cells and serum contribute to immunity!,MacFarlane Burnet （1899-1985）,克隆選擇學說 clonal selection theory,體內(nèi)事先就存有能識別各種抗原的細胞克隆(clone)，每一細胞表面均有對特定抗原的受體，能與相應抗原結合而識別它們?？乖淖饔迷谟谶x擇與其相應的細胞克隆與其受體結合后，引起細胞的增殖分化，產(chǎn)生免疫應答，產(chǎn)生大量抗體（即免疫球蛋白）。,抗體形成理論 -克隆選擇學說,體內(nèi)存在無數(shù)抗原特異性淋巴細胞克隆 胚胎期與自身成分反應的淋巴細胞被“禁忌”形成耐受 出生后淋巴細胞遇到相應抗原發(fā)生特異應

9、答，并形成記憶 禁忌細胞突變可導致自身免疫,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)免疫學理論研究 抗體多樣性和特異性的遺傳學基礎 T細胞抗原受體的基因克隆 免疫遺傳學和MHC限制性的發(fā)現(xiàn) 細胞因子及其受體 信號轉導的研究 危險信號學說,(2)免疫學應用研究： 基因工程疫苗 基因工

10、程制備重組細胞因子 免疫細胞治療 治療性抗體,免疫（immunity) 傳統(tǒng)概念指免除疫病、免除感染，指機體抗感染的防御能力。 現(xiàn)代概念指機體對“自己”或“非己”的識別并排除“非己”的功能。,免疫的基本功能,免疫系統(tǒng) (immune system)：機體執(zhí)行免疫功能的組織、器官、細胞和分子構成免疫系統(tǒng)。,The four kinds of pathogens that cause human disease,常見的病原微生物,Overview of immune responses,固有免疫 （innate immunity） 是機體抵御病原微生物入侵的第一道防線，并啟動和參與適應性免疫應答。

11、 天然免疫（natural immunity)或非特異性免疫(nonspecific immunity)，是個體出生時就具有的免疫力，通過遺傳獲得，是生物在長期進化過程中逐漸形成的，其針對外來異物的范圍廣，反應迅速，其應答模式和強度不因與病原微生物的反復接觸而改變。,固有免疫系統(tǒng)的組成,屏障 細胞 分子,皮膚黏膜屏障：物理、化學、微生物 血-腦屏障、血-胸腺屏障 血-胎屏障、氣-血屏障,巨噬細胞、中性粒細胞、樹突狀細胞、T 細胞、NK細胞、NKT細胞、B1細胞、肥大細胞、嗜堿性粒細胞和嗜酸性粒細胞等。,抗菌肽、溶菌酶、急性期蛋白、補體、細胞因子和黏附分子、,Epithelial barrier

12、s prevent the entry of microbes,固有免疫細胞,Phagocyte NK ILLs（固有樣淋巴細胞） DC MC Basophil Eosinophil, T細胞 NKT細胞 B1細胞,Monocyte-macrophage Neutrophil,肺部巨噬細胞吞噬大腸桿菌,Phagocytosis by innate immunity,固有性免疫分子,指體表分泌液以及血漿和其它體液中能夠識別或攻擊病原體的可溶性分子。,抗菌肽 antimicrobial peptides 溶菌酶 lysozyme 急性期蛋白(acute phase proteins, APP) 脂

13、多糖結合蛋白（LBP） 血清淀粉樣蛋白（SAP） 甘露糖結合蛋白（MBP） C反應蛋白等（CRP） 補體 細胞因子和黏附分子,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 Immuno

14、logy in 20th 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 Pa

15、tterns) with 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. Strasbour

16、g, France,The “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, Pe

17、ptidoglycan, 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

18、also recognize 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）表面存在一些人體所沒有的，但可為許多相關微生物所共享、結構恒定、進化保守的分子結構。,損傷相關分子模式 （damage-associated molecular patterns，DAMPs）,機體自身細胞所釋放的內(nèi)源性分子，即內(nèi)源性危險信號，來源于受損或壞死組織和某些激活的免疫細胞。主要有HMGB1、熱體克蛋白等。,PA

19、MP vs DAMP,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 activ

20、ate inflammasomes,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),適應性免疫 （adaptive immunity）,是機體獲得性、抗原特異性、抵抗病原微生物感

21、染的高效防御機制。 獲得性免疫（acquired immunity)或特異性免疫(specific immunity)，是個體出生后，在環(huán)境中受抗原刺激所產(chǎn)生的免疫力，針對特定抗原，有特異性、多樣性、記憶性和耐受性。 1) 特異性，對某個特定的異物性抗原能引起特異性免疫應答；指抗原特異性。 2) 多樣性，機體可針對環(huán)境中多種多樣的抗原，分別建立起不同的特異性免疫應答；多樣性是特異性產(chǎn)生的基礎。 3) 記憶性，當異物抗原再次入侵時，可產(chǎn)生快而強的再次免疫應答效應；記憶性淋巴細胞。4) 耐受性，正常情況下，免疫系統(tǒng)對自身成分有保護性的免疫耐受；,抗原決定簇Antigenic determinant

22、，AD,抗原分子表面具有特殊立體構型和免疫活性的化學基團稱為抗原決定簇或抗原決定基。由于抗原決定簇通常位于抗原分子表面，因而又稱為抗原表位(epitope)。 抗原決定簇抗原決定基 抗原表位 抗原決定簇決定抗原的特異性，即決定抗原與抗體發(fā)生特異性結合的能力（實際是抗原決定簇與抗體的結合）。,AD的數(shù)目、性質和空間構象決定抗原特異性 抗原以AD與相應抗原受體及抗體特異性結合,APC加工處理的抗原種類: 外源性抗原(exogenous antigen): 通過吞噬或吞飲等作用被APC從細胞外攝入的抗原，以抗原肽-MHC I I類分子復合物形式提呈給CD4+T細胞 。 內(nèi)源性抗原(endogenou

23、s antigen): 細胞內(nèi)合成的抗原，以抗原肽-MHC I類分子復合物形式提呈給CD8+T細胞 。,外源性抗原加工，處理及提呈,APC 攝取的外源性抗原在內(nèi)體中降解成肽，與 MHC類分子(在內(nèi)質網(wǎng)合成) 結合后表達于細胞表面。外源性抗原加工中需要 Ii 鏈和 HLA-DM 分子的參與。Ii 鏈 與 MHC類分子的轉運有關，并通過 CLIP 封閉 MHC類分子的肽結合部位，阻止 MHC-類分子在內(nèi)質網(wǎng)中與內(nèi)源性抗原肽結合。HLA-DM 分子促使 CLIP 從 MHC類分子肽結合區(qū)解離，有利抗原肽與 MHC類分子結合。,內(nèi)源性抗原加工，處理及提呈,內(nèi)源性抗原經(jīng)蛋白酶體降解成肽，通過抗原加工相關

24、轉運體(TAP1、TAP2)轉運進入內(nèi)質網(wǎng)，與 MHC類分子(在內(nèi)質網(wǎng)合成)結合成肽-MHCI類復合物，通過高爾基體表達于細胞表面。 TAP是內(nèi)質網(wǎng)上的異源性二聚體，由TAP-1及TAP-2基因編碼胞漿中蛋白酶體（proteasomes, 核心成分為低分子量多肽LMP,細胞被病毒感染后出現(xiàn)的病毒蛋白，基因突變后產(chǎn)生的腫瘤抗原,THE ADAPTIVE IMMUNE RESPONSE,Antibody-Mediated Immunity (AMI) Involves B lymphocytes, plasma cells and antibodies Humoral immunity Name

25、derives from 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.

26、 Antibody (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

27、,1、抗原提呈與識別階段（感應階段）： 2、活化、增殖、分化階段（反應階段）： T細胞活化、增殖分化為效應T細胞； B細胞活化、增殖分化為漿細胞； 部分細胞發(fā)育為記憶細胞。 3、效應階段： 效應T細胞對抗原的清除； 漿細胞分泌抗體清除抗原。,免疫應答的三個階段,Overview of adaptive immune responses,CELL-MEDIATED IMMUNITY (CMI),Directed against intracellular microorganisms Non-phagocytic cells and phagocytic cells T-lymphocytes

28、(T cells) Differentiate 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 s

29、election,Functional 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

30、 cells before 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

31、 in T cell 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 (

32、CD8 and CD4-TH1 cells).,T細胞受體復合物 由TCR和CD3組成。前者識別和結合抗原肽, 后者將TCR獲得的抗原信號傳遞至細胞內(nèi)。,T細胞對抗原的識別,APC,T細胞,T細胞活化的雙信號刺激 第一信號：TCR對MHCII抗原肽復合物的識別，CD3分子將第一信號傳遞到細胞內(nèi)。 第二信號：CD28識別專職APC上的B7分子,又稱協(xié)同刺激信號。,Effector T cells,In contrast to terminally differentiated B cells (plasma cells), there are several types of terminall

33、y differentiated 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 molecule

34、s),The immune 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 patie

35、nts have a 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/

36、Th17 cells,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)

37、Immunoglobulin G (IgG) Immunoglobulin A (IgA) Immunoglobulin D (IgD) Immunoglobulin E (IgE),抗體的功能 V區(qū)的功能 識別并特異性結合抗原 單體（IgG, IgE) 2價 二聚體(分泌型IgA) 4價 五聚體(IgM) 10價 中和效應 中和毒素和病毒 與Ag結合 促吞噬細胞吞噬,抗體的結合價,實際意義,C區(qū)的功能 1.激活補體系統(tǒng) Ab(IgM、IgG) + Ag C1q 補體經(jīng)典途徑 IgG4、IgA和 IgE的凝聚物 補體旁路途徑 2.介導免疫細胞活性 (1)調(diào)理作用（opsonization）：I

38、gG + 抗原(顆粒性) FcR（單核、巨噬細胞及中性粒細胞） 促吞噬細胞吞噬； (2)ADCC：IgG + 抗原(靶細胞) Fc R（NK 細胞） 殺傷靶細胞； (3)介導超敏反應：型、型和型超敏反應。 3.穿越胎盤和粘膜,Antibody-Dependent Cellular Cytotoxicity (ADCC),Th2與B細胞的相互作用，獲得第二信號：協(xié)同刺激信號,CD40-CD40L,活化的Th2細胞分泌細胞因子及表達CD40L，輔助B細胞活化,第二信號（Th細胞信號） 有二種方式 （1）Th細胞-B細胞間接觸作用：CD40L-CD40等 （2）Th細胞分泌細胞因子：IL-4、5、6

39、等,胸腺依賴性抗原（TD-Ag）,Specificity, Memory, and Homeostasis of Adaptive Immunity,體液免疫應答一般規(guī)律,多克隆抗體(polyclonal antibody，PcAb )：采用傳統(tǒng)的免疫方法，將抗原物質經(jīng)不同的途徑進入動物體內(nèi)，經(jīng)數(shù)次免疫后采取動物血液，分離出血清，由此獲得的抗血清即為多克隆抗體。用天然的抗原物質免疫動物，刺激多個B細胞克隆所獲得的免疫血清（含多種特異性抗體）。 單克隆抗體(Monoclonal Antibody，McAb):由一個B細胞分化增殖的子代細胞產(chǎn)生的針對單一抗原決定簇的抗體，稱單克隆抗體。 由一個B細

40、胞克隆產(chǎn)生。 識別一種抗原表位。 高度均一（結構、特異性）。 雜交瘤技術制備。 基因工程抗體：利用基因工程技術來制備的抗體分子稱為基因工程抗體，是分子水平的抗體。,US和EU所批準的治療性抗體,鼠源性單克隆抗體將逐漸被人源化抗體所替代：鼠源性單克隆抗體與人補體成分結合能力低，CDC作用相應較弱，對腫瘤細胞的殺傷能力較弱；它與NK等免疫細胞表面Fc受體親和力弱，介導的 ADCC作用較弱；鼠源抗體在人血循環(huán)中的半衰期短，它發(fā)揮ADCC與CDC作用的時間較短；鼠單克隆抗體具有免疫原性，宿主易產(chǎn)生抗抗體引起過敏反應。,抗體人源化改造及人源抗體制備,人-鼠嵌合抗體：應用基因工程技術將小鼠單克隆抗體的恒定

41、區(qū)用人源抗體恒定區(qū)代替而拼接成嵌合抗體。 改型抗體如CDR移植、SDR移植：用鼠單克隆抗體的CDR、SDR移植到人源抗體可變區(qū)，替代人源抗體CDR、SDR。 表面氨基酸殘基人源化,抗體人源化的主要技術,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,細胞因子的研究熱點 1、新細胞因子的基因克隆化 2、細胞因子受體的基因克隆化 3、細胞因子信號轉導機制 4、新一代細胞因子：高活性，多功能，低毒副作用，長半衰期