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Antigen

chapter 2. Antigen. 抗原.  Conceptions  Immunogenicity and Specificity of Antigen  Classification of Antigen  Superantigen and Adjuvant. Ⅰ . Conception.

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Antigen

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  1. chapter 2 Antigen 抗原  Conceptions  Immunogenicity and Specificity of Antigen  Classification of Antigen  Superantigenand Adjuvant

  2. Ⅰ.Conception Antigen (抗原) Complete antigen (完全抗原) Hapten (半抗原) Tolerogen (耐受原) Allergen (变应原)

  3. 1.Antigen (Ag) pathogen→B cell →corresponding antibody (Ab) combine specifically Ag A.Definition of Ag B ---抗原是能与B、T 淋巴细胞抗原识别受体结合,启动免疫应答,并能与应答产物 ( 抗体或效应T细胞) 发生特异性结合的物质 ︱ BCR —TCR B.2 important properties of Ag T immunogenicity antigenicity

  4. B.2 important properties of Ag  Immunogenicity antigen ↓ IS ↓induce IR ↓ products of IR (Ab/effector T cells) Combine specifically ---the ability for inducing an IR, including induce production of antibody and effector T cell 免疫原性是指能够刺激机体产生特异性免疫应答，包括诱导产生抗体及效应性T 淋巴细胞的能力 Antigenicity/immunoreactivity →immunogenicity →antigenicity ---the ability to combine specifically with the Ab or effector T cell induced by its own ---能与其诱生的抗体或效应性T细胞发生特异性结合的能力,称为抗原性或免疫 反应性

  5. 2.Complete antigen & hapten A.Complete antigen (完全抗原) ---Substances that have both immuno-genicity and immunoreactivity(antigenicity) B.Hapten(半抗原) ---Substances that have immunoreactivity, butlack of immunogenicity

  6. (二硝基苯) 半抗原 combine with (有免疫反应性) combine with combine with anti-dinitrobezene (抗二硝基苯) (无免疫原性) (有免疫原性) •Hapten couple(偶联) to protein or other carriers (载体) to form complete antigen •hapten+carrier = complete antigen

  7. 3.Tolerogen & allergen Tolerogen antigen→ →T/B → → response negative (state of specific nonresponse) “immune tolerance” (免疫耐受) Allergen antigen → →T/B → → high response “hypersensitivity/allergy” (超敏反应/变态反应)

  8. 1.Decisive factors for immunogenicity Ⅱ.Immunogenicity and Specificity of antigen A.Foreigness(异物性) • various microbes • allogenic substance • heterogenic protein (such as immune sera)  Non-self substances  Self tissue (including: changed or cryptical) 在胚胎期未与免疫活性细胞充分接触过的物质均为异物 B.Physicochemical characteristics

  9. B.Physicochemical characteristics Chemical propertyMolecule weight Glutin (明胶) Glutin +2% tyrosine→→ (酪氨酸) Y Y MW>100kD 免疫原性弱 免疫原性增强 Complexity of structureMolecular conformation and accessibility （分子构象和易接近性）

  10. Tyrosine Glutan poly-alanine poly-lysine Immunogenicity +++ ± +++ 分子构象和易接近性不同,其免疫原性也不同 Physical property

  11. C.Host D.Immunized route Genetic characteristics of the host Age, sex, and state of health

  12. 2. Specificity of antigen 多价抗原 多价抗原 induce AD binding to AD specificity of immunogenicity specificity of immunoreactivity A.Antigenic determinant (AD) 抗原分子中决定抗原特异性的特殊化学基团称为抗原决定基,又称为表位(epitope);是与TCR/ BCR及抗体特异性结合的基本单位 Antigenic valence 能与抗体结合的抗原决定基(表位)的数目,称为抗原的结合价

  13. A. Antigenic determinant (AD) AD  Definition Ag 抗原分子中决定抗原特异性的特殊化学基团称为抗原决定基,又称为表位(epitope); 是与TCR/BCR及抗体特异性结 合的基本单位 Ag B antigen Ag antigen T

  14. The chemical composition and spatial structure of AD decide specificity of Ag (半抗原) 抗间位氨基苯磺酸抗体 苯磺酸基 苯砷酸基 甲酸基

  15.  Antigenic valence AD ---The numbers of epitope which can bind to antibody 多价 抗原 能与抗体结合的抗原决定基(表位)的数目,称为抗原的结合价 *Natural antigen is polyvalent antigen

  16. B.Classification of AD According to structure of AD • linear determinant •conformational determinant  According to location of AD on Ag molecule • functional determinant • cryptical determinant  According to AD recognized byT or B cell • T cell epitope • B cell epitope  Hapten epitope and carrier epitope (i.e. B cell epitope and T cell epitope)

  17. •T cell epitope---epitope recognized by TCR *linear determinant *location in the insideof antigen 1,2: B细胞表位 3 :T 细胞表位 T细胞只识别经加工处理的线性表位，一般不识别构象决定基 2 •B cell epitope---epitope recognized by BCR/Ab 3 1 *conformational determinant or linear determinant *location on the surfaceof natural antigen 3 B细胞可识别线性表位或构象决定基，且无需加工处理

  18. C.Common antigen and cross-reaction  Common antigen 两种不同抗原具有相同或相似的抗原决定簇,则称为共同抗原(common antigen) Cross-reaction 抗体对具有相同或相似的抗原决定簇的不同抗原的反应,称为交叉反应(共同抗原又称交叉反应抗原) 交叉反应 Ag1 Ag2

  19. 1.Depend on whether need the Th cell for producing the antibody Ⅲ. Classification of antigen A.Thymus dependent antigen(TD-Ag) B.Thymus independent antigen(TI-Ag)

  20. 2. Depend on the consanguinity between the Ag and organism (亲缘关系) • Xenogenic Ag • （异种抗原） • B. Allogenic Ag • （同种异型抗原） • C.Autoantigen（自身抗原） • D.Heterophilic antigen (异嗜性抗原) or Forssam antigen • E.Idiotype Ag

  21. Ⅳ.Superantigen and adjuvant 1. Superantigen A.Conception B. Types 一种在极低浓度下(1~10ng/ml)即可激活大量T细胞克隆,并产生极强的免疫应答的特殊抗原类物质,称为超抗原 exogenous superantigen 如金葡菌肠毒素A~E endogenous superantigen 如逆转录病毒的蛋白产物 TCR+T cell superantigen 如热休克蛋白(HSP) B cell superantigen 如金葡菌蛋白A(SPA) C.Characteristic and mechanism

  22. a terminal of SAg directly binding to nonpolymorphic region of MHC-Ⅱ the other terminal of SAg combine with TCRV of CD4+T cell *The difference between common Ag and Sag (Conbinate site, not processed by APC, no restriction-MHC)

  23. 2.Adjuvant A.Conception 某些物质预先或与抗原同时注入体内，可增强机体对该抗原的免疫应答或改变免疫应答类型,此类 物质称为佐剂 B.Types 卡介苗、脂多糖、弗氏佐剂…… C.Mechanisms D.Use

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