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Flashcards in Hypersensitivity Deck (14)
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Types of hypersensitivity reaction

Type I-III = antibody mediated

Type IV = cell mediated


Type I hypersensitivity

The cause of anaphylactic shock

Mediated by IgE antibodies which cause mast cell activation

Stimulated by soluble antigen

Following initial exposure to antigen, IgE antibodies remain bound to mast cells, so subsequent exposure to the antigen causes rapid degranulation


Allergic rhinitis

A type I hypersensitivity reaction

Allergen is collected and presented to Th2 cells

This causes release of IL-3, IL-4 and IL-5 which cause class-switching, resulting in IgE production



A type I hypersensitivity reaction

Occurs when the allergic reaction is localised to the lungs

Leads to bronchial constriction


Type II hypersensitivity

Occurs when IgG (or IgM) antibodies are directed against self-cells

IgG binding causes opsonisation and complement fixation, leading to immune cell recruitment which damages the cells/tissue

Triggered by normally harmless foreign antigen


Goodpasture's syndrome

A type II hypersensitivity response

Antibodies target the basement membrane in the lung or kidney

Linked to viral infections


Autoimmune haemolytic anaemia

A type II hypersensitivity response

Antibodies target native erythrocytes via blood group antigens

Leads to lysis of RBCs


Grave's disease

A type II hypersensitivity response

Antibodies target the thymic stimulating hormone receptor

Leads to receptor activation and thyroid hormone synthesis


Myasthenia gravis

A type II hypersensitivity response

Antibodies block nicotinic acetylcholine receptors at the post-synaptic neuromuscular junction


Type III hypersensitivity

Occurs when IgG antibodies bind with soluble antigens

Self-antigens will be continually present so this leads to immune complexes becoming trapped in areas of the body

This activates immune cells, leading to tissue damage


Serum sickness

A type III hypersensitivity response

Triggered by injection of poorly catabolised foreign antigen

Results in deposition of immune complexes in blood vessels


Systemic lupus erythematosus

A type III hypersensitivity response

Occurs when antibodies target cytoplasmic antigens, leading to the deposition of immune complexes all over the body


Type IV hypersensitivity

Delayed & T-cell mediated



A type IV hypersensitivity reaction

Granulomas form in response to persistent antigen and act to separate the antigen from the rest of the body