Section 4
Immunity Disorders: Hypersensitivity
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Version 6
By Boundless
By Boundless
Boundless Microbiology
Microbiology
by Boundless
5 concepts
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Type I (Anaphylactic) Reactions
Type I (or immediate/anaphylactic) hypersensitivity can be caused by the body's response to a foreign substance.
![Thumbnail](../../../../../../figures.boundless-cdn.com/12951/square/allergy-skin-testing.jpeg)
Diagnosis and Treatment of Allergy
Allergy testing can help confirm or rule out allergies, reducing adverse reactions and limiting unnecessary avoidance and medications.
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Type II (Cytotoxic) Reactions
In type II (cytotoxic) hypersensitivity, the antibodies produced by the immune response bind to antigens on the patient's own cell surfaces.
![Thumbnail](../../../../../../figures.boundless-cdn.com/12970/square/phritis-iga-immunostaining.jpeg)
Type III (Immune Complex) Reactions
Type III hypersensitivity occurs when there is little antibody and an excess of antigen, leading to the formation of small immune complexes.
![Thumbnail](../../../../../../figures.boundless-cdn.com/13384/square/ntoux-tuberculin-skin-test.jpeg)
Type IV (Delayed Cell-Mediated) Reactions
Type IV hypersensitivity reactions are cell-mediated and take 2 to 3 days to develop.