Hypersensitivity

Question 1

Which hypersensitivities can lead to tissue damage?

Answer 1

Hypersensitivity 2 and 4

Question 2

Which hypersensitivities are mediated by antibodies?

Answer 2

Hypersensitivity 2 and 3

Question 3

Which hypersensitivity is responsible for ALLERGIC reaction?

Answer 3

Hypersensitivity 1

Question 4

Which hypersensitivity is involves T cell mediated DTH?

Answer 4

Hypersensitivity 4

Question 5

What is the mechanism of hypersensitivity 1?

Answer 5

1. Th2 cells with cytokine IL-4
2. trigger class switch in B cells
3. IgE circulating binds FceR1 on MAST Cells and leads to activation of mast cell
4. cross linking signal increases mast cell degranulation
5. mediators increase inflammation

Question 6

What receptor is important for Hypersenstivity 1 ? Which Antibody is involved ?

Answer 6

FceR1 receptor , IgE

Question 7

What is immediate phase of H-Sensitivity 1 ?

Answer 7

increase in edema , vasodilationm, sm muscle contraction

Question 8

What is latent phase of H-Sensitivity 1 ?

Answer 8

2-24 hours later … increase in leukocytes to the area (neutrophils, eusinophils and macrophages

Question 9

What are the clinical syndromes of H-Sensitivity 1 ?

Answer 9

1. asthma- increased capillary permeability in lungs , SOB

2. anaphylaxis - bronchi sm muscle vasodilation , decrease in BP

Question 10

What can we use to detect Type 1?

Answer 10

Allergen testing

Question 11

What is Hypersensitivity 2?

Answer 11

IgM and IgG against surface (cell surface or extracellular matrix

Question 12

What are the mechanisms of Hypersensitivity 2? (2 main)

Answer 12

1. Complement-mediated (cytotoxic)
   • Opsonization ( increase in C3a / C5a or recruitment and activation of inflammatory cells )
   - ENHANCES Phagocytosis (via FcRy / CR1 receptors)

2.Non-cytotoxic
• Change in physiologic behavior of a cell

Question 13

Examples of Non-cytoxic effects of hypersensitivity 2?

Answer 13

1. GRAVES disease

2. Myasthenia gravis

Question 14

Graves disease?

• type of sensitivity?
• mechanism?
• sxs

Answer 14

1. Type 2
2. Ab binds TSH receptor stimulating TSh release without hormone (non cytotoxic)
3. hyperthyroidism

Question 15

Myasthenia Gravis

• type of sensitivity?
• mechanism?
• sxs

Answer 15

1. Type 2
2. Ab inhibits Acetycholine binding Ach receptor (non -cytotoxic)
3. muscle weakness

Question 16

Good pasture syndrome..

• type of sensitivity?
• mechanism?

Answer 16

1. Type 2
2. Ab binds protein in kidney glomeruli and lungs (cytotoxic ;complement/ Fc receptors)
3. nephritis and lung hemmorhage

Question 17

Rheumatic Fever..

• type of sensitivity?
• mechanism?
• sxs

Answer 17

1. Type 2
2. Ab binds strep cell wall Ag (cytotoxic; phagocytosis)
3. myocarditis

Question 18

What is Type 3 hypersensitivity?

Answer 18

Complement-mediated recruitment and activation of inflammatory cells resulting in some combination of arthritis, vasculitis and/or nephritis.

Question 19

How does quinidine work ?

Answer 19

binds C3b —> to RBC—> hemolytic anemia

Question 20

How does alpha-methyldopa work?

Answer 20

binds directly to RBC self Ag—-> hemolysis . (phagocytosis)

Question 21

Systemic Lupus and inflammation response ?

Answer 21

nephritis, vasculitis , arthritis

Question 22

Poststreptoccoal Glomuleronephritis and inflammation response ?

Answer 22

nephritis

Question 23

Serum Sickness and inflammation response ?

Answer 23

SYSTEMIC vasculitis/ nephritis due to immune complex build up in circulation

Question 24

Arthrus Reaction and inflammation response ?

Answer 24

LOCAL vasculitis , immune complex build up in local area

Question 25

What is (2) mechanisms of type 4 hypersensitivity ?

Answer 25

``` Cytokine-mediated tissue damage • T cell IFN-y activation of macrophage • IL-17 recruitment and activation of neutrophil Direct killing • CTL-mediated cellular death ```

Question 26

Which T cells are involved in DTH ?

Answer 26

Th1 and Th17

Question 27

What are two major triggers of Hypersensitivity 4?

Answer 27

1. M tuberculosis | 2. contact by poison ivy, metals, chemicals

Question 28

What is the principle difference between type II and type III hypersensitivity? a. whether Ab reacts with Ag on cell or reacts with Ag before it interacts with cell b. the class isotoype of Ab c. the participation of complement d. the participation of T cells

Answer 28

A. Type 2 deals with Ab binding to cell surface or ECM Ag Type 3 involves Immune complex formation before interaction with cell

Question 29

two important properties of allergens?

Answer 29

1. binds with specificity to IgE | 2. can bind IgE with LOW concentration (low threshhold)