Hypersensitivity refers to a condition in which immune system produce a response against antigens (also called allergens) that results in excessive reactions leading to tissue damage.
Classification of Hypersensitivity
Hypersensitivity Reactions are;
1. Immediate hypersensitivity reaction
2. Delayed hypersensitivity reaction
1. Immediate hypersensitivity reaction
This type of hypersensitivity occurs in few minutes to few hours. It is mediated by humoral antibody.
Types of Immediate Hypersensitivity Reaction
Type l Hypersensitivity; Anaphylaxis - Antibody mediated
Type ll Hypersensitivity; Cytotoxic/Cytolytic- antibodies mediated
Type lll Hypersensitivity; Immune complex reaction -Ab mediated
2. Delayed hypersensitivity reaction
This type of hypersensitivity occurs slowly, usually after 24 hours and reaches maximum after 48-72 hours. It is mediated by T cells.
Type lV hypersensitivity; delayed type of hypersensitivity - cell mediated
3. Type V hypersensitivity; Stimulatory type reaction - Ab mediated
4. Type Vl hypersensitivity; Antibodies dependent cell- mediated. Cytotoxicity; Both Ab and cell mediated
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