Type I hypersensitivity | |
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Other names | Immediate hypersensitivity |
Image showing the mechanism of activation of type 1 hypersensitivity in a mast cell. | |
Specialty | Immunology |
Type I hypersensitivity (or immediate hypersensitivity), in the Gell and Coombs classification of allergic reactions, is an allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen.[1] Type I is distinct from type II, type III and type IV hypersensitivities. The relevance of the Gell and Coombs classification of allergic reactions has been questioned in the modern-day understanding of allergy, and it has limited utility in clinical practice.[2]
Exposure may be by ingestion, inhalation, injection, or direct contact.