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《Immunology》Lecture 3 ： B Cell and Antibody

《Immunology》Lecture 3 ： B Cell and Antibody. Feng Zhang (Ph.D) Office ： Biological Building Room 402 Email ： zhangfeng@imau.edu.cn. 3.1 B Cell. Born in the bone marrow 1 billion B cell per day per guy Early stage: select gene coding 2 kinds of BCR proteins and relocate to B cell surface.

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《Immunology》Lecture 3 ： B Cell and Antibody

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  1. 《Immunology》Lecture 3：B Cell and Antibody Feng Zhang(Ph.D) Office：Biological BuildingRoom 402 Email：zhangfeng@imau.edu.cn

  2. 3.1 B Cell • Born in the bone marrow • 1 billion B cell per day per guy • Early stage: select gene coding 2 kinds of BCR proteins and relocate to B cell surface. • BCR v.s. Antibody • Very simillar • Antibody lack anchor sequence

  3. 3.1.1 BCR • Components: 2H + 2L • Gene localized on Chromosome 14

  4. 3.1.2 How BCRtransfer signal • Homologous /cognate antigen • Epitope

  5. 3.1.3 B Cell activation With Th help:

  6. Without Th help: • Repeat epitopes  BCR • Mitogens (error activation)

  7. BCR crosslinking + ?  activation • BCR crosslinking  proliferation but no antibodies secreted! • Only with 2nd signal: from innate Immune sys (such as IFN- γ) • Other reason: T cell only recognize proteins, so with Th help, only for proteins, but not for other molecules like lipid or saccharides..

  8. 3.1.4 Class Switching

  9. 3.2 Antibody

  10. 3.2.1 IgM

  11. 3.2.2 IgG • Subtype: IgG1, 2,3 • ADCC (antibody dependent cellular cytotoxicity) • Neutralize virues • Penetrate blood-placenta barrier • Half life: about 3 weeks (v.s. IgM 1 day)

  12. 3.2.3 IgA

  13. 3.2.4 IgE

  14. 3.3 SOMATIC HYPERMUTATION • Normal: single base mutation rate: 1/100million • In V, D, J region: 1/1000 • Increase the high affinity to antigen- optimization! • Affinity mutation • Only for B cell activated by Th.

  15. 3.4 B CELLS MAKE A CAREER CHOICE Plasma cells are antibody factories. Memory B cells are not produced when B cells are activated without T cell help.

  16. SUMMARY FIGURE

  17. Questions • B cells are produced according to the principle of clonal selection. Exactly what does this mean? • 2. Describe what happens during T cell-dependent activation of B cells. • 3. Describe “fail-safe” systems that are involved in B cell activation. • 4. How can B cells be activated without T cell help? • 5. Why is T cell-independent activation of B cells important in defending us against certain pathogens? • 6. Describe the main attributes of IgM, IgG, IgA, and IgE antibodies. • 7. Why do class switching and somatic hypermutation produce B cells that are better able to defend against invaders? • 8. Why do most mast cells wait until their second exposure to an allergen before they degranulate? Hint: Think about the timing.

  18. 1， B细胞是通过克隆选择理论产生的，这是什么意思？ • 2， 请详述T细胞依赖的B细胞活化。 • 3， 请详述在B细胞活化过程中的两个保险体系。 • 4， 请详述在没有T细胞辅助的情况下B细胞是如何被激活的。 • 5， 为什么非依赖T细胞的B细胞活化对于我们防御特定病原体是如此重要？ • 6， 详述IgM、IgG和IgA的主要作用。 • 7， 为什么经过类型转换和体细胞高突变产生的B细胞可以更好地防御入侵者？

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