Exam 3: Dr. Pharr Hypersensitivity

Question 1

What is hypersensitivity?

Answer 1

Exaggerated immune responses that cause inflammation and tissue damage

Question 2

What are the 4 types of hypersensitivity reactions and their effector mechanisms?

Answer 2

Type I: IgE-mediated hypersensitivity to harmless antigens
Type II: Antibody-mediated destruction of cells
Type III: Immune complex mediated
Type IV: T-cell mediated

Question 3

What is a type I hypersensitivity reaction?

Answer 3

Allergic response to harmless environmental antigen

Question 4

What is an allergy?

Answer 4

A state of hypersensitivity to a non-harmful antigen

Question 5

What is sensitization of type I hypersensitivity reactions?

Answer 5

Initial exposure generates a primary immune response

Question 6

When do germinal centers form?

Answer 6

In the second week of the primary response

Question 7

What do germinal centers do?

Answer 7

Isotype switching to IgE
Memory B cells and long-lived plasma cells
Mast cells express the high-affinity Fc receptor for IgE and therefore bind free IgE from the blood

Question 8

When does the early phase of type I hypersensitivity reactions local response occur?

Answer 8

Immediately

Question 9

What is the effector function of IgE?

Answer 9

Activation of mast cells, which degranulate and release histamine and TNF-α

Question 10

When does the late phase of type I hypersensitivity reactions local response occur?

Answer 10

After 6-8 hours

Question 11

What is involved in mast cell synthesis?

Answer 11

Prostaglandins and leukotrienes came vasodilation and vascular permeability
Cytokines and chemokines recruit leukocytes

Question 12

Describe the emigration of eosinophils in response to mast cell-derived chemokines in type I hypersensitivity reactions

Answer 12

Respond to mast cell-derived cytokines

Release tissue damaging proteases

Question 13

Describe the emigration of basophils in response to mast cell-derived chemokines in type I hypersensitivity reactions

Answer 13

IgE mediated activation or respond to mast cell-derived cytokines
Release histamine

Question 14

What does the emigration of leukocytes in response to mast cell-derived chemokines in type I hypersensitivity reactions result in?

Answer 14

Narrowing of the airway or sustained edema

Question 15

What is the systemic response of type I hypersensitivity reactions?

Answer 15

Allergen enters the bloodstream:

IgE-mediated activation of mast cells

Question 16

What is anaphylaxis?

Answer 16

An immediate type I hypersensitivity reaction causing circulatory shock and suffocation due to bronchiole constriction

Question 17

What does histamine release by mast cells do?

Answer 17

Vasodilation and vascular permeability – decreases blood pressure
Bronchial smooth muscle contraction
Intestinal smooth muscle contraction

Question 18

What are examples of allergens?

Answer 18

Drugs
Insect venoms
Foods

Question 19

What is the sensitization of type II hypersensitivity reactions?

Answer 19

Some drugs can bind to self protein and induce a primary immune response i allergic individuals

Question 20

What is a classic examples of type II hypersensitivity reactions?

Answer 20

Antibiotics such as penicillin

Question 21

Describe drug-induced hemolytic anemia

Answer 21

Drug binds to delf proteins to generate new epitope
Activation of a primary response to a new epitope
Germinal center formation results high affinity

Question 22

What could future exposure of the drug in type II hypersensitivity reactions cause?

Answer 22

Antibiotics bind to self proteins

Drug-induced IgG binds to the surface of RBCs

Question 23

What is drug-induce hemolytic anemia?

Answer 23

RBCs are opsonized by IgG and activated complement C3b. This results in the removal of opsonized erythrocytes by macrophages in the spleen

Question 24

What is the local response of type III hypersensitivity reactions?

Answer 24

Artus reactions–immune complexes form in the tissue, cause localized inflammation

Question 25

What is a classic example of type III hypersensitivity local response reactions?

Answer 25

Booster vaccination sometimes results in swelling and/or pain at the injection site Residual antibodies from previous vaccination form immune complexes with the vaccine antigen

Question 26

What is an immune complex?

Answer 26

Antibody with its antigen

Question 27

What will immune complexes in type III hypersensitivity reactions do?

Answer 27

Activate the classical pathway of complement

Question 28

Describe complement activation in type III hypersensitivity reactions

Answer 28

Proinflammatory | Mast cells will degranulate in response C5a and signals through the Fc receptor for IgG

Question 29

What is the systemic response of type IIII hypersensitivity reactions?

Answer 29

Serum sickness–immune complexes form n the bloodstream | Immune complexes can form in the capillaries of a number of tissues and induce inflammation

Question 30

What is a classic examples of a systemic response to type III hypersensitivity reactions?

Answer 30

Treatment for snake bites. Antiserum from horses immunized with snake venoms

Question 31

What can the antiserum from horses occur with?

Answer 31

Injection of a large amount of poorly catabolized foreign antigen (horse IgG)

Question 32

When does the immune response to horse IgG occur?

Answer 32

Within 7-10 days

Question 33

What is the sensitization phase of the delayed-tpye hypersensitivity in type IV hypersensitivity reactions?

Answer 33

Primary immune response

Question 34

What is the elicitation phase of the delayed-tpye hypersensitivity in type IV hypersensitivity reactions?

Answer 34

Mediated by memory Th1 helper T cells

Question 35

What is the classic example of delayed type hypersensitivity of type IV hypersensitivity reactions?

Answer 35

Tuberculin skin test | Requires previous infection with Mycobacterium tuberculosis or vaccination with the BCG

Question 36

What are other test for cel-mediated immunity in type IV hypersensitivity reactions?

Answer 36

Anthraxin test | Candidin test

Question 37

What is anthraxin test?

Answer 37

Bacillus anthracis | Cell wall preparation from the attenuated strain

Question 38

What is the candidin test?

Answer 38

Yeast extract from Candida albicans

Question 39

What are type IV hypersensitivity reactions due to?

Answer 39

Intracellular pathogens

Question 40

Is a delayed-type hypersensitivity of a type IV hypersensitivity reaction duet an allergy?

Answer 40

No

Question 41

What is a contact hypersensitivity of a type IV hypersensitivity reaction?

Answer 41

Allergic response to chemically modified self proteins

Question 42

What is a classic example of contact hypersensitivity of type IV hypersensitivity reactions?

Answer 42

Poison ivy Chemical from the leaf, pentadecacatechol, is lipid soluble The chemical can form covalent bonds and modify extracellular skin proteins (presented by MHC class II) or enter a cell and modify intracellular proteins (presented by MHC classI)

Question 43

What happens with allergic contact dermatitis in type IV hypersensitivity reactions?

Answer 43

Activation of memory Th1 helper T cells; pro-inflammatory cytokines Activation of memory CTL; cellular cytotoxicity and IFN-γ

Question 44

What are the 2 types of contact dermatitis?

Answer 44

Allergic contact dermatitis | Irritant contant dermatitis

Question 45

What is allergic contact dermatitis?

Answer 45

Immunological form | Allergic response to an antigen

Question 46

What is irritant contact dermatitis?

Answer 46

Non-immunological form Response to chemical to irritate or traumatize the skin No sensitization Can occur immediately

Question 47

What is a mechanism for irritant contact dermatitis?

Answer 47

A wide range of chemicals can activate keratinocytes to produce pro-inflammatory cytokines and chemokines