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lecture 7 Immunology Hypersensitivity Dr. Dalia Galal
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Page 1: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

lecture 7 Immunology

Hypersensitivity

Dr. Dalia Galal

Page 2: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Hypersensitive Reactions

1. Type I Hypersensitivity

2. Type II Hypersensitivity

3. Type III Hypersensitivity

4. Type IV Hypersensitivity

Page 3: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

1. Basic concepts1. Basic concepts

Hypersensitivity reactions are harmful immune responses , occur when an

individual who has been primed by an antigen, produce tissue injury and

dysfunction.

Allergen : the antigens that give rise to immediate hypersensitivity

Atopy : the genetic predisposition to synthesize inappropriate levels of IgE

specific for external allergens

Types of hypersensitivity : I 、 II 、 III 、 IV

Page 4: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

1) 、 Characteristics

2) 、 Components and cells

3) 、 The process and mechanism

4) 、 Common diseases of type I Hypersensitivity

2. 2. Type I hypersensitivity

Page 5: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

1) Characteristics

Occur and resolve quickly

Mediated by serum IgE

Systemic and tissue dysfunction

Genetic predisposition

Page 6: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Allergen : pollen 、 dust mite 、 insects etc

selectively activate CD4+Th2 cells and B cells

Allergin ( IgE ) and its production

IgE : mainly produced by mucosal B cells in the lamina prapria

IL-4 is essential to switch B cells to IgE production

High affinity receptor of the IgE on mast cell and basophil

And Eosinophil

2) Components and cells in Type I hypersensitivity

Page 7: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.
Page 8: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

3 The process and mechanism of Type I hypersensitivity

1) Priming stage:last more than half a year

2) Activating stage:

Crosslinkage Enzyme reaction Degranulation of mast cell , basophil

3) Effect stage:

Immediate/early phase response: Mediated by histamine

Start within seconds

Last several hours

Late-phase response : Mediated by new-synthesized lipid mediators

Take up 8-12hours to develop

Last several days

Page 9: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.
Page 10: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Allergen

Degranulation ,release and synthesis of biological mediators of primed target cells

LOXCOXAcetyl-transferases

Phosphoration of ITAM MAPK

Lipid mediatiors

Endoplasmic reticulum

Degranulation

Myosin

Phosphoration of

Light chain

Cell membrane

Activation of PTK

Phosphatidylcholine

Histamine

Arachidonic acid

Inactivated PKC

ActivatedPKC

Hydroxyl phosphalipid Phosphalipid

Page 11: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

The biological mediator on effect stage

1. Histamine:

Dilate blood vessel and Increase vascular permeability

2. Leukotrienes:

Bronchial smooth muscles contract Asthmas

3. Prostaglandin (PGE ):High concentration of PGE Inhibit the secretion of histamine

low concentration of PGE promote the release of histamine

4. Platelet activating factor (PAF) :

Agglutinate and activate platelets to release histamine

5. Eosinophil chemotactic factor ( ECF-A ) :

6. Bradykinin :

Vasodilator function

Page 12: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

4. Skin allergy:

4. Common disease of type I hypersensitivity

1.  Systemic anaphylaxis: a very dangerous syndrome

1) Anaphylactic drug allergy : penicillin

2) Anaphylactic serum allergy :2. Respiratory allergic diseases :

1) Allergic asthma : acute response, chronic response

2) Allergic rhinitis

3. Gastrointestinal allergic diseases :

The lack of IgA protein hydrolase Undigested protein Allergen

Page 13: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

3. 3. Type II Hypersensitivity

1. Characteristic features

2. Mechanism of Type II Hypersensitivity

3. Common diseases of Type II Hypersensitivity

Page 14: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

1. Characteristic features

Primed IgG or IgM + Antigen on membrane

Injury and dysfunction of target cells

Page 15: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Allergen

Stimulate Antibody

A. Opsonic phagocytosis

D. ADCC of NK

C. Effect of complement

Combined opsonic activities

Cell injury ways of type II hypersensitivity

Cell

Page 16: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

2. Mechanism of Type II hypersentivity

1. Surface antigen on target cells

Target cells: Normal tissue cell, changed or modified self tissue cells

2. Antibody, complement and modified self-cell

Antigen : Blood group antigen, Common antigen,

Self-antigen modified by physical factors or infection

Drug antigen,

Antigen-antibody complex

Activate complement Lyse target cells Opsonic phogacytosis Destroy target cells

Kill the target cellsMacrophage+ 、 Natural killer cells NK 、 + T cells

Stimulating or blocking effect Promote /surpress the target cell funcion

Page 17: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Antigen or hapten on cell

Antibody (IgG, IgM)

Activate complement

Lyse target cell

Opsonic phagocytosis NK , phagocyte Stimulate / block

Destroy target cell ADCC

Target cell injury Change the function ofTarget cell

Mechanism of Type II hypersensitivity

Page 18: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

3. Common disease of type II hypersensitivity 1)Transfusion reaction

2) Hemolytic disease of newborn

3) Autoimmune hemolytic anemia and type II drug reaction i. Foreign antigen or hapten Penicillin RBC hemolytic anemia

Quinin Platlet thrombocytopenic purpura

Pyramidone Granulocyte agranulocytosis

ii. Self-antigen

Drug conversion from a hapten to a full antigen

induce self antibody autoimmune hemolytic anemia

Page 19: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

4. Type III4. Type III hypersensitivityhypersensitivity

1. Characteristics

2. Mechanism of type III hypersensitivity

3. Common disease of type III hypersensitivity

Page 20: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

1 、 characteristics

Free Ag + Primed Ab Larger immune complex

Deposit in tissue or blood vessel wall  

Inflammation

Page 21: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

2 、 Mechanism of type III hypersensitivity

Formation of the intermediate immune complex

Deposition of the intermediate immune complex

Tissue injury by the immune complex

Page 22: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Soluble antigen Body Antibody

Immune complex

Small molecular soluble Immune complex

intermediate molecular soluble Immune complex

Large molecular insoluble Immune complex

Deposit on the basement of capillaries

Combine and activate complement system

C3a,C5a,C3b

Infiltration of neutrophils

Phagocytose complex

Release the enzymes in lysosome

Tissue injury

Eliminate by phogacytosis

Platelets

Bleeding Edema

Local or systemic immune complex diseases

Page 23: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

3. common disease of type III hypersensitivity 1. Local immune complex disease Arthus reaction : Experimental local reaction,

Necrotic vasculitis vasculitis, Ulcer

Human local reaction: insulin-dependent diabetes mellitus (IDDM)

2. Acute systemic immune complex disease    serum sickness 

antigen (Pinicillin 、 Sulfanilamide ) + Anti-serum Ab+Ag systemic tissue

injury ,fever, arthritis, skin rash

3. Chronic immune complex disease systemic lupus erthymatosus SLE

Rheumatoid arthritis : RF+IgG Deposit on synovial membrane

Page 24: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

5. Type IV hypersensitivity 5. Type IV hypersensitivity

1 、 Characteristics of type IV hypersensitivity

2、 Mechanism of type IV hypersensitivity

3 、 Common diseases of type IV

hypersensitivity

Page 25: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

1. Characteristics

Interaction of primed T cells and associated antigen

Infiltration of Mononuclear Cells, Inflammatory response

Page 26: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

2. Mechanism of type IV hypersensitivity

Formation of effector and memory T cells

Inflammation and cytotoxicity caused by effector T cells

1) Inflammation and tissue injury mediated by CD4+Th1

Release chemokines and cytokines

Immune injury mainly caused by infiltration of mononuclear cells and lymphocytes

2) Cytotoxicity of CD8+CTL

Page 27: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

Antigen T cell(CD4+,CD8+)

Secondary contact

Induce

Primed T cell

CD4+ T cell

CD8+ T cell

ReleaseCytokines

IL-2TNF-INF-

TFMCFMIFMAFSRF

Directly kill target cells

Infiltration of monocyte and M

Proliferation of T cell

Exudation and edema

Inflammation characterized by infiltration of M , monocyte, And tissue injury

Mechanism of type IV hypersensitivity

Page 28: Lecture 7 Immunology Hypersensitivity Dr. Dalia Galal.

3. Common disease of type IV hypersensitivity

1) Infectious delayed type hypersensitivity

OT( Old Tuberculin ) test

2) Contact dermatitis :

Paint, drug red rash, papula, water blister, dermatitis

3) Acute rejection of allogenic transplantation and

immune response in local tumor mass

Same disease (SLE), multiple immune injury ,hypersensitivity involved

Same drug (penicillin), several types of hypersensitivity