Hypersensitivity 1

Question 1

What are the 4 types of hypersensitivity disorders?

Answer 1

I- Immediate hypersensitivity
II- Direct cell killing
III- Immune complex mediated
IV- Delayed hypersensitivity

Question 2

Allergic responses are Type _ disease.

Answer 2

I

Question 3

An allergic reaction is an _ mediated response to an allergen.

Answer 3

IgE

Question 4

Examples of some common allergies. (4)

Answer 4

1. Allergic triad- asthma, eczema, rhinitis
2. Urticaria
3. Angioedema
4. Food, drugs

Question 5

Why is the prevalence of allergic disease on the rise?

DONT Memorise

Answer 5

Westernised countries- improved sanitation & vaccination, children have lower exposure to common pathogens.

More likely to develop allergic disease

Question 6

What is the pathophysiology of allergic reactions? (4)

Answer 6

1. Production of specific IgE directed against allergen
2. IgE-allergen complex binds to mast cells via Fc receptors
3. Degranulation of mast cells
4. Release of pre-formed and newly synthesised inflammatory molecules eg histamine and leukotrienes

Question 7

Allergic reactions occur within minutes to a couple of hours. T/F?

Answer 7

True

Question 8

Clinical presentation of allergic diseases? (8)

Answer 8

1. Asthma
2. Urticaria
3. Hay fever
4. Angioedema
5. Anaphylaxis
6. Rhinits
7. Conjuctivitis
8. Diarrhoea vomiting

Question 9

Some common allergens? (6)

Answer 9

1. Pollen
2. Dust mite
3. Animal dander
4. Nuts
5. Drugs
6. Venom

Question 10

Upon activation, what do mast cells release?

Answer 10

1. Preformed- Histaimen, tryptase, heparin

2. Synthesised on demand- leukotrienes, cytokines (IL4, TNF), prostaglandins

Question 11

IgE antibodies bind to mast cells via _ receptors.

Answer 11

Fc

Question 12

Mast cell release is primarily seen in the first exposure to the allergen. T/F?

Answer 12

False- Re-exposure triggers mast cell release

Question 13

What is angioedema?

Answer 13

Self limiting localised swelling of tissue under submucosal membrane

Question 14

What are the two types of oedema useful in clinical examination?

Answer 14

Pitting and non pitting

Pitting- indentation of an area remains after releasing applied pressure

Question 15

Spontaneous mast cell degranulation is an example of an IgE mediated allergic reaction. T/F?

Answer 15

False- non IgE mediated

Question 16

What are some examples of non IgE allergic reactions?

Answer 16

1. Drugs
2. Thyroid disease
3. Physical urticaria (response to heat & pressure)

Question 17

A common drug that can induce asthma in a a fifth of asthmatics is _.

Answer 17

Aspirin & other NSAIDS like ibuprofen

Question 18

What specific investigations are useful for allergic diseases?

Answer 18

1. Skin prick test. (gold standard)
2. Quantitate specific IgE to specific allergen
3. Challenge test- supervised exposure to putative allergen.

If acute anaphylactic reaction- check serum mast cell tryptase levels

Question 19

What is quantitive IgE test?

Answer 19

Measures amount of IgE in serum directed against a specific allergen

Question 20

Rise in tryptase levels occur in both anaphylactic and local reactions. T/F?

Answer 20

False- only anaphylaxis

Question 21

What are the different management options for IgE mediated allergies?

Answer 21

1. Targeted avoidance
2. Block mast cell activation
3. Prevent effects of mast cell activation
4. Anti-inflammatories
5. Anaphylaxis management
6. Immunotherapy

Question 22

Sodium cromoglycate is an exampe of?

Answer 22

Mast cell stabiliser- blocks its activation.

Used as a spray

Question 23

What are the two drug classes that prevent the effects of mast cell activation?

Answer 23

1. Anti-histamines
2. Luekotriene receptor antagonist- blocks effects of leukotrienes produced by mast cells after activation. Eg Montelukast

Question 24

Example of anti-inflammatories?

Answer 24

Corticosteroids

Question 25

How do you treat anaphylaxis?

Answer 25

1. Self administered adrenaline- arterial vasoconstriction (increased BP, reduced permeability) but bronchial dilation relaxing airways

Question 26

What does immunotherapy involve?

Answer 26

Controlled slow steady exposure to allergen