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Chapter 17 Chapter 17

ImmunoregulationImmunoregulation

Chapter 17 Chapter 17

ImmunoregulationImmunoregulation

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Chapter 17 Immunoregulation

The ability of the immune system to control and regulate its own responses is called immunoregulation.

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• To keep the individual homeostasis by regulating the balance between immunocyte and immunocyte, between immunocyte and immune molecule, and between immune system and nerve system /endocrine system.

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PartⅠ Immunoregulation on genetic level

PartⅡ Immunoregulation on molecular level

PartⅢ Immunoregulation on cellular level

PartⅣ Immunoregulation on individual and mass level

Contents

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PartⅠ Regulation on genetic level

Immune response of individual controled by hereditary background:

• Genes encode TCR and BCR• Genes encode molecules regulating

immune response: MHC ?

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• Regulation of Ag• Regulation of Ab• Regulation of Complement• Regulation of co-stimulator and

receptor

PartⅡ Regulation on molecular level

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1. Regulation of antigen

Origination stage of immune response:

• Route of Ag entrance a individual • Dosage of Ag• Structural characteristic: antigen

competition

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2. Regulation of antibody

• Regulation of immune complex: IgM, IgG

• Regulation of idotype-anti-idiotype network

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2. Regulation of antibody

• Regulation of Ag-Ab complex to immune response-----Antibody feedback regulation

• IgM ---- positive feedback regulation

• IgG ---- negative feedback regulation

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g

B cell

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FcRⅡB

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Idiotypic determinant or idiotype: a unique determinant on an antibody ,usually formed by one or more of the hypervariable regions.

Idiotypic determinant may be recognized as “foreign” in an individual, but they are usually present in quantities too low to induce self-tolerance.

Anti-idiotypic antibody: antibodies against idiotype of antibodies -------- internal image of Ag

2. Regulation of idiotypic networks

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Ab2β Ab2α

YYB

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3. Regulation of complements

• Promote APC capture antigens:

CR1 receptor on APC capture C3b-Ag-Ab complex

• Promote the activation of B cell:

CR1, CR2 on B cell

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4. Regulation of co-stimulator and receptor

• T cell: B7 ------ CD28, CTLA-4

• B cell: CD40L ------ CD40, FcRⅡB

5. Regulation of cytokines

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PartⅢ Regulation on cellular level

 • Regulation of T cells: Natural regulatory T cells(Treg): CD4+CD25+foxp3+

Th cell subset

• Regulation of B cells• AICD (activation induced cell death)

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 The immunoregulation of T cell

subsets

Th1 cells promote the cellular immunity suppressing the humoral immunity.

Th2 cells promote the humoral immunity suppressing the cellular immunity.

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Th1

+IL-12 +IL-4

IL-2 IFN-

IL-4 IL-10

inhibit

Cell mediated immunity

Humoral immunity

Th0

Th2

Interaction of Th1 and Th2

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Regulation of T cell subset by different cytokines

• T cell subset Representative cytokine

• CD4+Th1 IL-2, IFN-γ• CD4+Th2 IL-4, IL-10• CD4+Th3 TGF-β• CD4+Th17 IL-17

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Activation-induced cell death （ AICD）

AICD: activated T or B cell apoptosis elicited by Fas(CD95)

• Apoptosis of target cell : FasL on Tc binds to Fas on target cells-----

induce the apoptosis of target cell.• Apoptosis of activated T cells: Fas is also expressed on activated Tc or B

cell, so FasL on activated T cell binds to Fas on activated T cell or B cell, then induces activated T cells or B cell apoptosis.

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(FasL)

(Fas)

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Part IV Regulation on systemic level

• Regulation of nerve-endocrine-immune system networks:

Nerve and endocrine regulate immune system.

Immune system regulate nerve and endocrine system.

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神经肽

免疫介质

内分泌激素

中枢神经系统中枢神经系统松果体激素

免疫系统免疫系统

免疫介质

内分泌激素内分泌系统内分泌系统

精神因素

Interaction of neuroendocrine system

and immune system

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