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Molecular Immunology > Lecture 14: Type 1 Hypersensitivity Reactions > Flashcards

Lecture 14: Type 1 Hypersensitivity Reactions Flashcards

1
Q

_____: adaptive immune responses that occur in exaggerated or inappropriate forms and result in disease

A

Hypersensitivity reactions

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2
Q

What is the pathologic immune mechanism associated with Type 1 Hypersensitivity reactions?

A

IgE antibody

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3
Q

What are the two primary mechanisms of tissue injury in Type 1 Hypersensitivity reactions?

A

1) Activation of mast cells, basophils, eosinophils + release of their mediators (histamine, arachidonic acid, cytokines)

2) Release of O2 and N2 radicals + proteases

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4
Q

What mechanisms of tissue injury are common to both Type II and Type III hypersensitivity reactions?

A

1) Activation of complement
2) Recruitment and activation of leukocytes (neutrophils, macrophages)

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5
Q

If a transfusion goes poorly, what type of hypersensitivity response will often occur?

A

Type 2

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6
Q

Auto-immunity, Arthus Reaction, or Serum Sickness are associated with which hypersensitivity?

A

Type 3

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7
Q

True or False: Type III hypersensitivity reactions are antibody mediated while Type II are immune complex mediated

A

False -

Type II reactions are: antibody mediated cytoxic/cytolytic reactions

Type III reactions are: immune complex-mediated

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8
Q

IgM or IgG antibodies against
tissue or cell surface antigen is seen in which hypersensitivity reaction?

A

Type II

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9
Q

Immune complexes of
circulating antigens and IgM or IgG antibodies are seen in which hypersensitivity reaction?

A

Type III

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10
Q

Which hypersensitivity reaction is T cell mediated?

A

Type IV

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11
Q

What are the two mechanisms of tissue injury used in Type IV hypersensitivity reactions?

A

1) Activated macrophages,
cytokines

2) Direct target cell lysis,
cytokines

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12
Q

Both CD4+ T cells (delayed type hypersensitivity) and CD8+ CTLs (T cell-mediated cytolysis) are present in which hypersensitivity reaction?

A

Type IV

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13
Q

Anaphylactic and allergic
reactions are associated with which type of hypersensitivity?

A

Type 1

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14
Q

There are often adverse responses mediated by___, which includes: allergies, asthma, and anaphylaxis

A

IgE

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15
Q

____: an antigen that stimulates IgE-mediated reactions (pollen, dust,
animal dander, etc.)

A

allergen

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16
Q

_____: an adverse response provoked by an allergen, mediated by
IgE, results in vasodilation and constriction of smooth muscles (including those of the bronchus), which can result in shock and death.

A

Anaphylaxis

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17
Q

____: susceptibility of certain individuals to natural sensitization by
environmental allergens, e.g., pollen, spores, foods

___: serum from a sensitized atopic individual that contains antibodies to an allergen

A

Atopy

Atopic serum

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18
Q

____: the process of inducing an immune response resulting in an
untoward (adverse) effect – for type I hypersensitivities it is the production
of IgE

A

Sensitization

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19
Q

What are the three phases of Type 1 hypersensitivity reactions?

A

Stage 1: Sensitization
Stage 2: Activation
Stage 3: Effector

20
Q

What are the steps of the sensitization phase?

A

1 - Exposure to allergen
2 - Th2 activation and IgE production
3 - IgE binds to mast cell Fc receptors

21
Q

What are the steps of the activation phase?

A

4 - 2nd exposure to allergen
5 - allergen binds to mast cell-associated IgE
6 - signal transduction

22
Q

What are the two steps of the effector phase?

A

7 - Mediator release (e.g. histamine)
8 - End organ effects of mediators

23
Q

What are four pre-disposing factors for sensitization?

A

1) Allergens (antigens that tend to drive Th2 responses and IgE production)

2) Route of exposure (location of mast cells in skin, mucosa, CT)

3) Age
4) Genetic predisposition

24
Q

In the second step of Type 1 Hypersensitivity reaction, ___ is synthesized.

A

IgE

25
Q

In the second step of Type 1 Hypersensitivity reaction,
______ activation
helps B cells commit to becoming ___

A

Th2 CD4+ lymphocyte ; IgE

26
Q

In the second step of Type 1 hypersensitivity reactions, ___, ___, and ____ strongly influence Th2-mediated B cell isotype switch and commitment to IgE production

A

IL-4, IL-5, and IL-13

27
Q

True or False: Most individuals can make IgE but only a few become atopic

A

True

28
Q

In the third step, IgE binds to a high affinity receptor on mast cells known as ____, thereby increasing IgE half life

A

FceRI

29
Q

Upon 2nd exposure to an allergen, more ___ is made by memory B cells

A

IgE

30
Q

Once allergen binds to the mast cell-associated IgE, ___ between two ___ molecules on mast cell surface occurs (signal transduction).

A

crosslinking; IgE molecules on mast cell surfaces

31
Q

Degranulation (release) of histamine, serotonin, heparin, proteases, etc. is associated with the ___ phase

A

effector

32
Q

True or False: In the 7th stage, there is a delayed release of newly
synthesized mediators

A

True

33
Q

In the 7th step, mast cell activation results in
release of newly synthesized
components, such as ___, ____, and ___

A

Leukotrienes, Prostaglandins, Thromboxanes

34
Q

In the 7th step, cytokine production also occurs, especially __ which potentiates Th2
responses.

A

IL-4

35
Q

GM-CSF, IL-3, and IL-5 are made in the 7th step. What is their shared role?

IL-8 is also made in the 7th step. What is it’s role?

A

Stimulate eosinophil growth and differentiation

Leukocyte chemotaxis

36
Q

True or False: Wheal and flare, vomiting and diarrhea, and enlarged nasal turbinates with blueish green mucosa are examples of mild, local symptoms of Type 1 Hypersensitivity reactions.

A

True

37
Q

What are two examples of severe Type 1 Hypersensitivity reactions?

A

1) Laryngeal edema
2) Severe systemic anaphylaxis

38
Q

True or False: Asthma, chronic obstructive airway, and respiratory inflammation can result due to type 1 reactions

A

True

39
Q

How long does the initial type 1 reaction response take? late phase response?

A

initial response: minutes
late phase: hours

40
Q

What are the three lethal outcomes of Type 1 hypersensitivity reactions?

A

1) Asphyxiation form laryngeal edema
2) Suffocation from bronchiolar constriction/contraction
3) Shock

41
Q

Type I hypersensitivities require antibodies of
which isotype?

A. IgG
B. IgA
C. IgM
D. IgD
E. IgE

A

E. IgE

42
Q

Sensitization requires which of the following
cell surface molecules?
A. FceRI
B. CD16
C. CD8
D. HLA-A

A

A. FceRI

43
Q

True or False: RIST and RAST are examples of in vitro tests used to diagnose type 1 hypersensitivity reactions

A

True
- note: RAST is more specific

44
Q

What are the two types of allergen immunotherapy?

A

1) SCIT
2) SLIT

45
Q

What are three types of hyposensitization mechanisms?

A

1) blocking antibodies
2) specific suppressor T cells
3) Th2 to Th1 switch

note: not the same as Drug desensitization!

46
Q

Two examples of immunotherapy?

A

1) Allergen immunotherapy - SCIT and SLIT
2) Hyposensitization mechanisms

47
Q

If a patient is taking OTC antihistamines for their
seasonal allergies, will they still produce anti-
allergen IgE?

A. Yes
B. No
C. They never produced IgE

A

A. Yes

Molecular Immunology (27 decks)

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