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Hypersensitivity: Wikis


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Classification and external resources
ICD-10 T78.4
ICD-9 995.3
DiseasesDB 28827
MeSH D006967

Hypersensitivity (also called hypersensitivity reaction) refers to undesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normal immune system. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. The four-group classification was expounded by P. H. G. Gell and Robin Coombs in 1963.[1]

Coombs and Gell classification

Comparison of hypersensitivity types[2]
Type Alternative names Often mentioned disorders Mediators
I Allergy (immediate)
II Cytotoxic, antibody-dependent
III Immune complex disease
IV Delayed-type hypersensitivity[3] (DTH), cell-mediated immune memory response, antibody-independent
V Autoimmune disease

Type 5

This is an additional type that is sometimes (often in Britain) used as a distinction from Type 2.[5]

Instead of binding to cell surface components, the antibodies recognize and bind to the cell surface receptors, which either prevents the intended ligand binding with the receptor or mimics the effects of the ligand, thus impairing cell signaling.

Some clinical examples:

The use of Type 5 is rare. These conditions are more frequently classified as Type 2, though sometimes they are specifically segregated into its own subcategory of Type 2.


  1. ^ Gell PGH, Coombs RRA, eds. Clinical Aspects of Immunology. 1st ed. Oxford, England: Blackwell; 1963.
  2. ^ Unless else specified in boxes, then ref is: Lippincott's Illustrated Reviews: Immunology. Paperback: 384 pages. Publisher: Lippincott Williams & Wilkins; (July 1, 2007). Language: English. ISBN 0781795435. ISBN 978-0781795432. Page 195
  3. ^ Black, CA. Delayed Type Hypersensitivity: Current Theories with an Historic Perspective Dermatol. Online J. (May 1999) 5(1):7 at
  4. ^ Table 5-1 in:Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson (2007). Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7.   8th edition.
  5. ^ Rajan TV (July 2003). "The Gell-Coombs classification of hypersensitivity reactions: a re-interpretation". Trends Immunol. 24 (7): 376–9. doi:10.1016/S1471-4906(03)00142-X. PMID 12860528.  

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