Flashcards in ENT - Allergy Deck (19)
What is the incidence of allergy in the UK?
Allergic Rhinitis 5.4%
Food Allergies 1-2%
Multiple allergies 3.7%
Rapid increase began in the 1960s
Increased in developed countries
What is the immunoglobulin driving allergic reactions?
What is allergy?
Hypersensitive disorder of the immune system.
Allergic reactions occur to normally harmless environmental substances known as allergens; these reactions are aquired.
The allergic reaction is an exaggerated or inappropriate immune reaction and causes damage to the host.
Name some common allergic reactions
What is an allergen?
Antigen that causes allergic reactions
How do allergic reactions vary?
Depending on the individual, allergen and mode of introduction.
Symptoms can be systemic or localised
e.g. asthma localised to respiratory system and eczema to dermis
What are some of the broad symptoms and signs of allergy?
Swelling and tenderness of the mouth
Flushing or rash
Burning and itching of skin
What is the pathophysiology of allergic reaction?
IgE mediated triggering of mast cells and subsequent accumulation of inflammatory cells at sites of antigen deposition
What is the pathophysiology of developing allergy?
Fist allergen exposure:
-Response with T cells and B cell producing IgE
IgE circulates in the blood and binds to an IgE-specific receptor (mast cells and basophils)
What is the acute allergic response?
Exposure of allergen
Allergen specific IgE
Degranulation with release of histamine, cytokines, interleukins, leukotrienes, and prostaglandins from their granules causing systemic effects, such as vasodilation, mucous secretion, nerve stimulation and smooth muscle contraction
What is the late phase response in allergy?
this is due to migration of other leukocytes, such as neutrophils, lymphocytes, eosinophils and macrophages to the initial site
What are the risk factors for allergy?
Host factors are HEREDITY, race and age
Environmental factors are alterations in exposure to infections diseases during early childhood, environmental pollution, allergen levels and dietary changes.
How is allergy diagnosed?
-responses to known allergens
(up to 15% false positives, +ve and -ve control used to minimise this)
-Presence and levels of allergen specific IgE
What is the treatment for allergy?
What is immunotherapy?
Give tiny, tiny amounts of allergen and slowly build up the dose.
Desensitising the immune system to allergen
Must be done under controlled conditions incase anaphylaxis
Very hard and a lot of work but only treatment to actually treat disease rather than symptomatic relief.
Useful for allergic rhinitis, allergic asthma, allergic conjunctivitis etc
Not for food allergy, urticaria, atopic dermatitis
What is the pharmacotherapy for allergy?
Several drugs: to prevent activation of cells and degranulation processes or to block the action of allergic mediators.
What is allergic rhinitis?
Allergic inflammation of the nasal airways
Occurs when allergen is inhaled by an individual with a sensitised immune system
What are the symptoms of allergic rhinitis?