Hypersensitivity Flashcards
What can cause hypersensitivty reactions
Infection
Harmless enviromental substances
Self-Antigen
What mediates a type I hypersensitivity reaction
Degranulation of mast cells and eosinophils
Describe the effects of a type 1 hypersensitivity reaction
immediate reaction to enviromental antigens
Rapid (mins)
IgE
What is type 1 hypersensitivty associated with
Atopy (allergy)
What symptoms can people get with type 1 hypersensitivity
Anaphylaxis Angiooidema urticaria rhintis asthma dermatitis
What produces IgE needed for type I
B cells produce is when costimulated with IL-4
What is urticaria
itchy edema of the cutaneous tissue
short lived
What is the treatment options for type 1 hyperses
B2 adrenergic agonists (salbutamol)
Epinephrine (adrenaline)
Antihistamines
Corticosteroids
What antibodies are involved in type 3 hypersensitivity
IgG or IgM
What is the process of type 2
The IgG or IgM interacts with antigens on the surface of cells. This allerts the complement or phagocyte system and tells it to destroy the cell. it is the basis of autoimmunitiy
What is the time scale of type II
takes several hours
what are examples of type 2
Blood groups Immune mediated haemolysis - Alloimmune haemolysis (rhesus) - autoimmine haemolysis -Goodpasture syndrome - Graves disease
Antibody is on blood that identifies its blood group
IgM
What antibody is involved with Rhesus
IgG
What antibody is involved in good pasture
IgG
What antibodies are responsible for type III hypersensitivity
IgG and IgM
What is the process of type 3
IgG or IgM bind to free floating antigens and form immune complexes. These complexes cause damage at the site of production or circulate and cause damage somewhere else. Normally the complement system clears these out of the system but if this fails then you get large immune complexes which cause disease
What conditions are caused by type 3 hypersensitivity
Glomerulonephritis
What mediates the type 4 hypersens
T cells
What is the time scale of type 4 hypersens
2-3 day
its called the delayed onset hypersens
Pre-sensitised T cells are produced from a previous contact with the antigen. Upon reexposure to the same antigen the T helper cells release inflammatory cytokines.
T killer cells induce cytotoxic reactions.
What are type 4 conditions
Rheumatoid arthrtis multiple sclerosis type I diabetes coeliac disease Contact dermatitis
What is the antigen that drives the reaction in rheumatoid
citrillunated proteins
What is the antigen that drives the reaction in MS
myelin
