ENT - allergy Flashcards
Define allergy
Chronic condition involving abnormal hypersensitive reaction produced by the immune system to an ordinarily harmless antigen called anallergen
What are the 2 types of rhinitis
ALLERGIC RHINITIS & NON-ALLERGIC RHINITIS
Allergic rhinitis is also known as
Hayfever
Define rhinitis
Nasal mucosa inflammation
Define allergic rhinitis
Nasal mucosa inflammation due to an allergen - e.g. pollen, cat hair, dust
Immediate symptoms of allergic rhinitis (4)
Itchy nose
Sneezing
Blocked nose
Rhinorrhoea (nasal discharge)
Late symptoms of allergic rhinitis (3)
Chronic obstruction
Hyposmia (Reduced smell)
Hyper-reactivity
Pathophysiology of allergic rhinitis (type 1 hypersensitivity reaction) (2)
Sensitisation to the allergen
-plasma cells produce specific IgE in response to allergen and IgE binds to mast cells
Re-exposure to the allergen
- stimulates that specific IgE to act against the allergen
- mast cell degranulation
What do mast cells contain (4)
Histamine, leukotrienes, prostaglandins, chemotactic factors
Effect of histamine release in allergic rhinitis
Vasodilation –> increasing vascular permeability
Effect of leukotriene release in allergic rhinitis
promotes inflammation by activating neutrophil production and recruiting them to the area
Effect of prostagrandin release in allergic rhinitis (2)
Smooth muscle contraction
Vasodilation
Effect of chemotactic factor release in allergic rhinitis
Leukocyte infiltration (esp eosinophils)
2 stages of type 1 hypersensitivity reaction
Acute (immediate response)
-minutes after exposure
Late phase response
-2-4hrs after exposure
What occurs in the acute immediate response of type 1 hypersensitivity reactions
Mast cell degranulation –> vasodilation, mucous secretion, nerve stimulation & smooth muscle contraction
What occurs in the late phase response of type 1 hypersensitivity reactions
Migration of other leukocytes (e.g. neutrophils, lymphocytes, eosinophils and macrophages) to the initial site
Name 3 factors that produce allergic reactions, e.g. eczema, asthma, food allergies
Host factors
Environmental factors
Occupational factors
List some host factors that contribute to allergic reactions (3)
Inherited
Race
Age
List some environmental factors that contribute to allergic reactions (3)
Exposure to infectious diseases during early childhood
Pollution
Dietary changes
List some occupational factors that contribute to allergic reactions (3)
Flour - bakers
Latex - health workers
Wood dust
Define intermittent allergic rhinitis
Symptoms <4 days per week OR <4 consecutive weeks
Define persistent allergic rhinitis
Symptoms >4 days per week AND >4 consecutive weeks
Investigations of allergic reactions (5)
Skin test RAST (radioallergosorben test) Total serum IgE Nasal allergen challenge Nasal cytology
How does the skin test work
Checks for immediate allergic reactions to as many as 40 different substances at once.
Small amounts of different allergens are placed on an individual’s skin, usually with a pinprick.
If allergic to these substances, will develop itchyhivesat these sites
How does the RAST (radioallergosorben test) work
Is a blood test so takes longer than skin test so skin test preferred
Looking for presence and levels of IgE against specific allergens in the blood
Negative RAST test = what concentration of IgE
Level 0: IgE <0.35kU/L
Treatment of allergic reactions (3)
Avoid allergen
Pharmacotherapy
Immunotherapy
Pharmacotherapy of allergic reactions (7)
Topical intranasal steroids
Systemic Steroids
Antihistamines - prevent vasoconstriction etc
LTRA
Sodium cromoglycate - inhibits degranulation of mast cells
Allergen Immunotherapy
Anti-IgE
How is immunotherapy used to treat allergic reactions
Stops body from producing specific IgE against the allergen by stopping it from recognising it as a foreign antigen
Patient is admitted to ITU and gradually increasing doses of the allergen are injected over 6 weeks for 3 consecutive years to allow immune system to become less sensitive to the allergen
