第11章-免疫系统与免疫功能.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Need for defense against intruders:,-virus；bacteria；pathogens,Need for eliminating abnormal cells,11.1 非特异性防御,人体对病原体侵害的防御共设置了三道防线。,皮肤、口腔、鼻腔、消化道与呼吸道中的黏膜及其分泌物等构成了第一道防线。,第一道防线对病原体不具有选择性或特异性，因此称为非特异性防御。,部分侵入到组织或细胞内的病原体还会受到人体内特殊免疫细胞与化学成分的抵御和攻击，吞噬作用、抗菌蛋白和炎症反应等构成了人体抵御病原体入侵的第二道防线。,这些特殊的免疫细胞与化学成分一般都是淋巴系统的组成部分。人体的淋巴系统是各种免疫细胞协同作用的网状系统，它们由淋巴管、淋巴结和包括胸腺、骨髓、脾脏和扁桃体等器官共同组成。,第三道防线：特异性免疫,First-line respiratory defenses,Phagocytosis by a macrophage,干扰素的作用机理,A simplified view of the inflammatory response,11.2 特异性反应,特异性免疫的发现：天花,Jenner Pasteur,可以引起人或动物体内免疫应答的特殊外来物质称为抗原。人体和哺乳动物对不同的抗原具有特殊的识别能力，并能立即作出相应的反应，释放出许多直接攻击入侵抗原的细胞，或者通过另一类细胞制造出相应的具有识别抗原功能的防御性蛋白质（抗体）。,种牛痘或患天花、麻疹等疾病痊愈以后，人体一种称为,B,细胞的淋巴细胞产生出游离于体液中的抗体蛋白，依靠,B,细胞的免疫方式称为体液免疫。,人体还能针对病原体产生出一种称为,T,细胞的淋巴细胞直接对病原体进行攻击，依靠,T,细胞的免疫方式称为细胞免疫。,B,细胞和,T,细胞的分化,当一种病毒或细菌突破了非特异性防御由呼吸道进入人体后，巨噬细胞便会立即启动免疫应答。,免疫系统的,T,细胞通过细胞表面,MHC,蛋白的进行自我与非我的识别。,MHC,分子嵌合抗原的细胞（抗原呈递细胞）将加工过的抗原提交给,T,细胞，进一步激活细胞毒性,T,细胞，最终杀死被病毒和细菌感染的细胞。,T,细胞及细胞介导的免疫应答,细胞介导的免疫应答可以防御病毒感染和癌症，杀死并消灭被感染的体细胞，同时也消灭了其中的病毒等病原体。,T,细胞介导的细胞免疫过程,When macrophages process the foreign antigens,they secrete interleukin-1,which stimulates cell division and proliferation of T cells.,Once the helper T cells have been activated by the antigens presented to them by the macrophages,they secrete the cytokines known as macrophage colony-stimulating factor and gamma interferon,which promote the activity of macrophages.,In addition,the helper T cells secrete interleukin-2,which stimulates the proliferation of,cytotoxic,T cells that are specific for the antigen(Interleukin-2 also stimulates B cells).,Cytotoxic,T cells can destroy infected cells only if those cells display the foreign antigen together with their MHC-I proteins.,The T cell immune defense.After a macrophage has processed an antigen,it releases interleukin-1,signaling helper T cells to bind to the antigen-MHC protein complex.This triggers the helper T cell to release nterleukin-2,which stimulates the multiplication of cytotoxic T cells.In addition,proliferation of cytotoxic T cells is stimulated when a T cell with a receptor that fits the antigen displayed by an antigen-presenting cell binds to the antigen-MHC protein complex.Body cells that have been infected by the antigen are destroyed by the cytotoxic T cells.As the infection subsides,suppressor T cells“turn off”the immune response.,B,细胞及体液介导的免疫应答,B cells also respond to helper T cells activated by interleukin-1.Like cytotoxic T cells,B cells have receptor proteins on their surface,one type of receptor for each type of B cell.B cells recognize invading microbes much as cytotoxic T cells recognize infected cells,but unlike cytotoxic T cells,they do not go on the attack themselves.,The way B cells do their marking is simple and fool-proof.Unlike the receptors on T cells,which bind only to antigen-MHC protein complexes on antigen-presenting cells,B cell receptors can bind to free,unprocessed antigens.When a B cell encounters an antigen,antigen particles will enter the B cell by endocytosis and get processed.Helper T cells that are able to recognize the specific antigen will bind to the antigen-MHC protein complex on the B cell and release interleukin-2,which stimulates the B cell to divide.In addition,free,unprocessed antigens stick to antibodies on the B cell surface.This antigen exposure triggers even more B cell proliferation.,B cells divide to produce long-lived memory B cells and plasma cells that serve as short-lived antibody factories.The antibodies are released into the blood plasma,lymph,and other extracellular fluids.,The B cell immune defense.Invading particles are bound by B cells,which interact with helper T cells and are activated to divide.The multiplying B cells produce either memory B cells or plasma cells that secrete antibodies which bind to invading microbes and tag them for destruction by macrophages.,B,细胞及体液介导的免疫应答,在体液免疫中，抗体是攻击病原体的分子级武器，它是一种,-,球蛋白,(,Ig),，,或称为免疫球蛋白。,免疫球蛋白的基本结构：,“,Y”,型的四链分子,按照抗体的结构与功能的差别，它们被分成,IgM,IgG,IgD,IgA,IgE,等,5,类,单克隆抗体,单克隆是指所有制备抗体的细胞都是同一个细胞的拷贝，因此其产生的抗体完全相同。,单克隆抗体是大规模细胞培养的产物，而不是直接来自于动物血清。,制备单克隆抗体的过程涉及到细胞培养、细胞融合等多种步骤。,11.3 免疫系统疾病,艾滋病是由人类免疫缺陷病毒（,HIV,）,引起的获得性免疫缺陷综合征。,HIV,是一种逆转录病毒，可特异性地侵犯,CD4+T,细胞，使人体细胞免疫功能被破坏。,HIV,感染人体的过程,HIV,感染,T,淋巴细胞的过程,