Allergy Flashcards
what is the main function of the immune response
Defence against external and internal antigens
what are consequences of the immune response
destruction of antigens
incidental collateral tissue damage
what is a hypersensitivity reaction
immune response that causes collateral damage to the self with exaggeration of normal immune mechanisms
what is type 1 mediated hypersensitivity
ALLERGY
an IgE mediated response
how quickly do type 1 hypersensitivity reactions take place
within minutes and up to 2 hours after exposure
how can type 1 allergic reactions present
urticaria
angioedema
asthma
anaphylaxis
Investigations for type 1 hypersensitivity reactions
Specific IgE blood tests
Skin prick test
Challenge test (only if SPT is negative)
serum mast cell trypase level (rises during anaphylaxis)
whats type 4 hypersensitivity
delayed hypersensitivity - antigen specific T cell mediated
example of type 4 hypersensitivity
allergic contact dermatitis
how quickly does a type 4 reaction occur
24-48 hours
how does contact allergic dermatitis present
reaction is present only at the site of exposure to allergen
Investigations for type 4 reactions
patch testing
how is patch testing done
allergens prepares in wells
places on back skin
taken of after 48 hours
reactions check at 48 and then 96 hours
how to manage contact allergic dermatitis
allergen/irritant avoidance allergen/irritant minimisation emollients topical steroids UV phototherapy Immunosupressants
what is contact irritant dermatitis
non-immunological dermatitis
does not require sensitisation
pattern depends on exposure
agents abrade, irritate and traumatise skin directly
