Infection: Allergies Flashcards Preview

ESA 3 > Infection: Allergies > Flashcards

Flashcards in Infection: Allergies Deck (8)
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1
Q

What does hypersensitivity mean?

A

Hypersensitivity is the antigen-specific immune responses that are excessive and result in harm to the host

2
Q

What is the sensitisation phase and effector phase?

A

The sensitisation phase is the first encounter with the pathogen - there is creation of IgE specific to the allergen which binds to mast cells.
The effector phase results in clinical pathology upon re-exposure to the same antigen. The allergen binds to the IgE in the mast cell causing release of huge amounts of inflammatory mediators.

3
Q

Why do people have allergies?

A

People living in westernised countries as opposed to developing countries have high antibiotic use, small families and stable intestinal microflora. This means that they have the TH2 phenotype and express IgE mediated type 1 hypersensitivity reactions

4
Q

What are some common allergens?

A

Insect venom (wasp and bee stings)
Milk, eggs, peanuts, sea food
Penicillin
Latex

5
Q

What is the effect of histamine during an allergic reaction?

A

Histamine binds to H1 receptors on the bronchi and causes the smooth muscle to contract making breathing difficult.
Histamine also causes dilation and increase permeability of the BV causing oedema (seen on the skin as urticaria)

6
Q

What is anaphylaxis?

A

Systemic activation of mast cells leading to hypotension, cardiovascular collapse, angioedema (swelling of face and neck) and bronchial constriction.

7
Q

What is the treatment of type 1 hypersensitivity reactions?

A

Antihistamines
Anti IgE
Corticosteroids - reduce the inflammatory response
Adrenaline given IM in severe anaphylaxis to constrict BV and reverse airways obstruction, also increases force of contraction of heart and reduces mast cell activation

8
Q

How can allergies be diagnosed?

A

Clinical history - seasonality, atopy
Blood test - look for allergen specific IgE
Skin prick tests - inject allergen into epidermis and look at mast cell reaction

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