Hypersensitivity

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

Hypersensitivity (also called hypersensitivity reaction) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. 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]

Contents

Coombs and Gell classification

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

Type V

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.

References

  1. ^ Gell PGH, Coombs RRA, eds. Clinical Aspects of Immunology. 1st ed. Oxford, England: Blackwell; 1963.
  2. ^ Black, CA. Delayed Type Hypersensitivity: Current Theories with an Historic Perspective Dermatol. Online J. (May 1999) 5(1):7 at http://dermatology.cdlib.org/DOJvol5num1/reviews/black.html
  3. ^ http://emedicine.medscape.com/article/136118-overview
  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. http://linkinghub.elsevier.com/retrieve/pii/S147149060300142X. 

External links