Allergies

Question 0

Understand the pathophysiology behind the types of hypersensitivity reactions

Answer 0

1st exposure (sensitisation):
Plasma cell --> antigen specific IgE 
2nd exposure (clinical pathology):
Histamine, chemokines --> vascular permeability, vasodilation, bronchial constriction

Question 1

Describe the different types of hypersensitivity reaction

Answer 1

Type I (immediate) - allergies
Type II (antibody mediated) 5-12h
Type III (immune complex mediated) 3-8h
Type IV (cell mediated) 24/48h

Question 2

Appreciate the clinical significance of hypersensitivity reactions

Answer 2

Vascular permeability
Vasodilation
Bronchial constriction
Skin manifestation - urticaria (mast cells in epidermis)
Face manifestation - angioedema (mast cells in deep dermis)
Systemic manifestation - anaphylaxis (systemic activation of mast cells)

Question 3

Explain the treatment and management of allergies

Answer 3

Treatment- adrenaline:
Reverses peripheral vasodilation
Reduces oedema
Relaxes bronchioles/bronchi
Increases force of heart
Inhibits mast cell activation 
Management:
Allergen avoidance/elimination
Education (e.g. of EPIPEN use)
Medic alert identification