Hypersensitivity and the Skin Flashcards
Allergic contact dermatitis is associated with which type of hypersensitivity?
IV
Type 1 allergy has which steps in its pathophysiology?
Antigen exposure
Dendritic cells present antigen to specific T cells
TH2 cells are activated and release IL4, 5 and 13
B cells are activated and begin IgE production
IgE induces mast cell degranulation
What is urticaria?
Red itchy skin rash associated with a type 1 hypersensitivity
What is the time frame for a type 1 hypersensitivity reaction?
Seconds to 2 hours
Which investigations can be used for type 1 hypersensitivity?
Skin prick
Challenge test (rarely recommended)
Serum mast cell tryptase levels
Specific IgE
Which type of investigation is associated with type IV hypersensitivity?
Patch testing
Which type of hypersensitivity is IgG mediated?
Type II
What is the gold standard for testing allergic contact dermatitis?
Patch testing
(allergic contact dermatitis is type IV hypersensitivity)
How is patch testing performed?
Allergens are attached to a patients back in separate chambers
Readings are taken to gaugue the respons eat 48 and 96 hours
What is the dosage for an adrenaline auto-injector in
a) Adults
b) Children
a) 300mcg
b) 150mcg
How quickly will and urticarial rash normally appear in type I hypersensitivity?
Within 1 hour
(usually last between 2 and 6 hours)
Why would an antihistamine be taken before an oral corticosteroid in the instance of food allergy?
Anti-histamines work quickly
(corticosteroids are more effective)
How is type IV hypersensitivity mediated?
T cells
For which reason is Coeliac disease not classed as an allergic condition?
It is not mediated by IgE
