Hypersensitivity Reaction Leacture

Question 1

Disorders of the immune system include?

Answer 1

Hypersensitivity reactions
Autoimmune diseases (caused by immune rxns against itself)
Immunologic deficiency syndromes (results from defects in normal immune responses)

Question 2

What does checks and balances in the immune system?

Answer 2

Inadequate control or inappropriately targeted

Question 3

What are some causes of hypersensitivity reactions?

Answer 3

Autoimmunity
Rxns against microbes 
Rxns against environmental antigens
Inappropriate control
Impossible to eliminate antigen
Positive feedback loops
--> chronic inflammation

Question 4

What is type I Hypersensitivity?

Answer 4

Allergy/Atopic disorders
Rapid
Production of IgE antibody
Strong TH2 responses
Release of mediators from mast cells
Can be fatal --> anaphylaxis

Question 5

How are mast cells activated?

Answer 5

Exposure to allergen –> activation of TH2 and IgE class switching in B cells –> IgE production –> binding of IgE to mast cells –> repeat exposure to the allergen –> activation

Question 6

What happens when cytokines are produced after mast cells are activated?

Answer 6

Late phase reaction

Question 7

What happens when vasoactive amines or lipid mediators are produced after mast cells are activated?

Answer 7

Immediate hypersensitivity reaction

Question 8

What is a late phase reaction?

Answer 8

Leukocyte infiltration
Epithelial damage
Bronchospasm

Question 9

What is a immediate reaction?

Answer 9

Vasodilation
Vascular leakage
Smooth muscle spasm

Question 10

Why does type I hypersensitivity occur?

Answer 10

Reaction dependent on TH2 and IgE primarily meant for combating parasitic infections
Helminthic infections –> IgE production/Mast cells/eosinophils

Question 11

Type II Hypersensitivity is what?

Answer 11

Antibody Mediated Diseases
Opsonization & phagocytosis
Inflammation
Antibody mediated cellular dysfunction

Question 12

What’s an example of opsonization and phagocytosis?

Answer 12

Autoimmune hemolytic anemia

Question 13

What’s an example of inflammation?

Answer 13

Goodpasture syndrome

Question 14

What are some antibody mediated cellular dysfunction?

Answer 14

Myasthenia Gravis

Graves Disease

Question 15

Type II Hypersensitivity is what?

Answer 15

Immune Complex Diseases
Antigen-Antibody Immune complexes
Exogenous or endogenous antigens
Size of complex is a critical determinatn
Deposit in blood vessels or in regions where blodd in filtered with high hemodynamic pressure
Inflammation

Question 16

What is acute serum sickness?

Answer 16

Foreign serum administered for passive immunization

Question 17

Type IV Hypersensitivity is what?

Answer 17

T Cell Mediated
CD4 T cells --> cytokine mediate inflammation 
Delayed type hypersensitivity
Macrophage mediated tissue damage
Granulomatous inflammation 
CD8 T cells --> direct cell toxitiy
 Type I diabetes mellitus

Question 18

Formation of granulomas occurs how?

Answer 18

APC binds an antigen and IL2 works on the CD4 TH1 cell

TNF goes to the creation of monocytes which are acted on by IFN-gamma

Question 19

TH17 causes what?

Answer 19

Inflammation and tissue injury

Question 20

TH1 causes what?

Answer 20

Macrophage activation and inflammation