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ESA 4 Rev > Type 1 hypersensitivity > Flashcards

Type 1 hypersensitivity Flashcards

1
Q

How long after exposure does a type 1 reaction occur?

A

Immediately <30 mins

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2
Q

Which T cell response is triggered in allergy?

A

TH2

TH1 triggered in non-allergic (immunotolerance)

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3
Q

What events occur following TH2 activation?

A

B- cells produce IgE.

IgE binds to mast cells and cause activation.

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4
Q

Why might there by more allergies in westernised countries?

A

Reduced Infection burden - “hygiene hypothesis”
Microbial dysbiosis - alterations in biome

Other- small families, good sanitation, high antibiotic use = more TH2 responses

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5
Q

Where are mast cells produced and where do they mature and differentiate?

A

Produced in bone marrow.

Mature and differentiate once in tissues.

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6
Q

Where are mast cells located?

A

Mucosal and epithelial tissues - GI tract, skin, resp epithelium

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7
Q

Give examples of mediators released by mast cells.

A 
Tryptase
Histamine
Cytokines + chemokines - IL-4
Leukotrienes C4, D4 and E4
Platelet-activating factor
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8
Q

What effect does histamine have?

A

Increased vascular permeability
SM contraction
Toxic to parasites

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9
Q

What does tryptase do?

A

Remodels connective tissue matrix

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10
Q

What do leukotrienes do?

A

SM constriction - Bronchoconstriction
Vascular permeability- hypotension and CV collapse
Mucus secretion

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11
Q

What does platelet-activating factor do?

A

Attracts leukocytes

Activates neutrophils, eosinophils + platelets

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12
Q

What happens upon 1st exposure to an allergen?

A

TH2 response and sensitisation produces IgE.

Antigen-specific IgE binds to mast cells and waits. No response.

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13
Q

What happens upon 2nd exposure to allergen?

A

Antigen binding causes IgE cross-linking of mast cells and degranulation. Allergic response.

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14
Q

What are the 3 main effects triggered by mast cell degranulation?

A
  1. Increased vascular permeability
  2. Vasodilation
  3. Bronchial constriction
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15
Q

What is urticaria?

A

Mast cell activation within the epidermis.

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16
Q

What is angioedema?

A

Mast cell activation in the deep dermis.

Lips, eyes, tongue and upper RT affected - emergency.

17
Q

What are the main mediators in angioedema?

A

Histamine + bradykinin

18
Q

What causes anaphylaxis?

A

Systemic activation of mast cells

19
Q

What are the signs/symptoms of anaphylaxis?

A 
Hypotension
CV collapse
Angioedema
Generalised urticaria 
Breathing problems
20
Q

What causes the signs/symptoms associated with anaphylaxis?

A

Vasodilation
Increased permeability
Bronchial constriction

21
Q

What treatment targeting the abnormal TH2 response can be used for allergies ?

A

Allergen desensitisation

Anti-IgE monoclonal antibody

22
Q

What treatment targeting mast cell degranulation can be used?

A

Anti-histamines
Leukotriene receptor antagonists
Corticosteroids

23
Q

What is sensitisation?

A

Activation of APCs and memory effector cells upon first exposure to an antigen.
Antigen specific IgE made.

24
Q

What if the effect of IL-4 secretion from mast cells?

A

Stimulate and activate TH2 response.

25
Q

What treatments are there aimed at symptoms of allergic reaction?

A

Anti-histamines
Leukotriene receptor antagonists
Corticosteroids

26
Q

What treatments are there aimed at desensitisation?

A

Allergen desensitisation

Anti-IgE mAb

27
Q

What 4 lifestyle advice could you give to somebody with an allergy?

A

Avoid the allergen
Carry epipen
Carry allergy card
Check labels

28
Q

What does prolonged epidermal exposure to antigens cause?

A

Eczema

Atopic dermatitis

29
Q

What type of reaction is anaphylaxis?

A

Systemic manifestation of type 1

30
Q

What are 5 signs/symptoms of anaphylaxis?

A 
Hypotension
CV collapse
Generalised urticaria 
Angioedema
Breathing problems

ESA 4 Rev (16 decks)

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