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Type IV hypersensitivity: Wikis

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From Wikipedia, the free encyclopedia

Hypersensitivity types
Type I - Allergy (immediate)
Type II - Cytotoxic, antibody-dependent
Type III - Immune complex disease
Type IV - Delayed-type hypersensitivity
(Antibody Independant)
Type V - Autoimmune disease
Type IV hypersensitivity
Classification and external resources
MeSH D006968

Type IV hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response.

CD8+ cytotoxic T cells and CD4+ helper T cells recognize antigen in a complex with either type 1 or 2 major histocompatibility complex. The antigen-presenting cells in this case are macrophages which secrete IL-12, which stimulates the proliferation of further CD4+ T cells. CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Type 1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact while activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells.

Examples

Disease Target antigen Effects
Diabetes mellitus type 1 Pancreatic beta cell proteins
(possibly insulin, Glutamate decarboxylase)
Multiple sclerosis Oligodendrocyte proteins
(myelin basic protein, proteolipid protein)
Rheumatoid arthritis - Type III Hypersensitivity Antigen in synovial membrane
(possibly type II collagen)
  • Chronic arthritis
  • Destruction of articular cartilage and bone
Some Peripheral neuropathies Schwann cell antigen
  • Neuritis
  • Paralysis
Crohn's disease Unknown
Contact dermatitis Environmental chemicals, e.g. poison ivy
Mantoux test* (diagnostic) Tuberculin
Unless else specified in boxes, then ref is: [1]

* - Mantoux test not taken from [1]

Some other clinical examples:

References

  1. ^ a b Table 5-5 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson. Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7.   8th edition.
  2. ^ "eMedicine - Hypersensitivity Reactions, Delayed : Article by Walter Duane Hinshaw". http://www.emedicine.com/MED/topic1100.htm.  
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