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Immunology - DVM year 1 > Exam 3: Dr. Pharr Hypersensitivity > Flashcards

Exam 3: Dr. Pharr Hypersensitivity Flashcards

1
Q

What is hypersensitivity?

A

Exaggerated immune responses that cause inflammation and tissue damage

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2
Q

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

A

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

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3
Q

What is a type I hypersensitivity reaction?

A

Allergic response to harmless environmental antigen

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4
Q

What is an allergy?

A

A state of hypersensitivity to a non-harmful antigen

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5
Q

What is sensitization of type I hypersensitivity reactions?

A

Initial exposure generates a primary immune response

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6
Q

When do germinal centers form?

A

In the second week of the primary response

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7
Q

What do germinal centers do?

A

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

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8
Q

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

A

Immediately

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9
Q

What is the effector function of IgE?

A

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

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10
Q

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

A

After 6-8 hours

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11
Q

What is involved in mast cell synthesis?

A

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

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12
Q

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

A

Respond to mast cell-derived cytokines

Release tissue damaging proteases

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13
Q

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

A

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

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14
Q

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

A

Narrowing of the airway or sustained edema

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15
Q

What is the systemic response of type I hypersensitivity reactions?

A

Allergen enters the bloodstream:

IgE-mediated activation of mast cells

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16
Q

What is anaphylaxis?

A

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

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17
Q

What does histamine release by mast cells do?

A

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

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18
Q

What are examples of allergens?

A

Drugs
Insect venoms
Foods

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19
Q

What is the sensitization of type II hypersensitivity reactions?

A

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

20
Q

What is a classic examples of type II hypersensitivity reactions?

A

Antibiotics such as penicillin

21
Q

Describe drug-induced hemolytic anemia

A

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

22
Q

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

A

Antibiotics bind to self proteins

Drug-induced IgG binds to the surface of RBCs

23
Q

What is drug-induce hemolytic anemia?

A

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

24
Q

What is the local response of type III hypersensitivity reactions?

A

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

25
Q

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

A

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

26
Q

What is an immune complex?

A

Antibody with its antigen

27
Q

What will immune complexes in type III hypersensitivity reactions do?

A

Activate the classical pathway of complement

28
Q

Describe complement activation in type III hypersensitivity reactions

A

Proinflammatory

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

29
Q

What is the systemic response of type IIII hypersensitivity reactions?

A

Serum sickness–immune complexes form n the bloodstream

Immune complexes can form in the capillaries of a number of tissues and induce inflammation

30
Q

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

A

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

31
Q

What can the antiserum from horses occur with?

A

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

32
Q

When does the immune response to horse IgG occur?

A

Within 7-10 days

33
Q

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

A

Primary immune response

34
Q

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

A

Mediated by memory Th1 helper T cells

35
Q

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

A

Tuberculin skin test

Requires previous infection with Mycobacterium tuberculosis or vaccination with the BCG

36
Q

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

A

Anthraxin test

Candidin test

37
Q

What is anthraxin test?

A

Bacillus anthracis

Cell wall preparation from the attenuated strain

38
Q

What is the candidin test?

A

Yeast extract from Candida albicans

39
Q

What are type IV hypersensitivity reactions due to?

A

Intracellular pathogens

40
Q

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

A

No

41
Q

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

A

Allergic response to chemically modified self proteins

42
Q

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

A

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)

43
Q

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

A

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

44
Q

What are the 2 types of contact dermatitis?

A

Allergic contact dermatitis

Irritant contant dermatitis

45
Q

What is allergic contact dermatitis?

A

Immunological form

Allergic response to an antigen

46
Q

What is irritant contact dermatitis?

A

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

47
Q

What is a mechanism for irritant contact dermatitis?

A

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

Immunology - DVM year 1 (35 decks)

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