Immunology + the skin Flashcards
Define allergy
a bad clinical reaction by the immune system to environmental antigens (allergens)
Define autoimmunityn
a bad clinical reaction by the immune system to self-antigens (autoantigens)
Describe type 1 hypersensitivity reaction
anaphylactic
antigen reacts with IgE bound to mast cells
Describe type 2 hypersensitivity reactions
cell-bound
IgM or IgG binds to antigen on cell surface
Describe type 3 hypersensitivity reactions
immune complex-mediated disease
free antigen and antibody (IgG, IgA) combine
Describe type 4 hypersensitivity reactions
delayed hypersensitivity
T-cell mediated
Describe type 5 hypersensitivity reactions
Antibodies that recognise and bind to the cell surface receptors.
This either stimulating them or blocking ligand binding
Colloquial term for urticaria?
hives
Describe urticaria and what causes it
short-lived swellings
caused by plasma leakage from capillaries in and below skin
main mediator for leakage = histamine (released from mast cells)
allergens/autoantibodies can trigger degranulation of mast cells
Test for type 1 hypersensitivity reactions?
skin prick testing
Describe bullous pemphigoid and what causes it
acquired blistering condition of skin and sometimes mucous membranes
autoantibodies against antigens in hemidesmosomes holding epidermis and dermis together cause inflammation leading to blisters
What type of hypersensitivity reaction is bullous pemphigoid?
type 2
What is vasculitis?
inflammation of blood vessels
How is allergic contact dermatitis diagnosed?
patch testing
What type of hypersensitivity reaction is allergic contact dermatitis?
type 4
