Type IV Hypersensitivity - Examples

Examples

Disease Target antigen Effects
Diabetes mellitus type 1 Pancreatic beta cell proteins
(possibly insulin, Glutamate decarboxylase)
  • Insulitis
  • Beta cell destruction
Multiple sclerosis Oligodendrocyte proteins
(myelin basic protein, proteolipid protein)
  • Demyelinating disease
  • Perivascular inflammation
  • Paralysis
  • Ocular lesions
Rheumatoid arthritis Antigen in synovial membrane
(possibly type II collagen)
  • Chronic arthritis
  • Destruction of articular cartilage and bone
Some peripheral neuropathies Schwann cell antigen
  • Neuritis
  • Paralysis
Hashimoto's Thyroiditis Thyroglobulin antigen
  • Hypothyroidism
  • Hard goiter
  • Follicular thymitis
Crohn's disease Unknown
  • Chronic inflammation of ileum and colon
Contact dermatitis Environmental chemicals, e.g. poison ivy, nickel
  • Dermatitis with usually short-lived itching
Mantoux test* (diagnostic) Tuberculin
  • Skin induration indicates TB exposure
Unless else specified in boxes, then ref is:

* - Mantoux test not taken from

The pathophysiology of the Tuberculin reaction is explained thus: M. tuberculosis are engulfed by macrophages after being identified as foreign, but due to a self-preserving mechanism peculiar to TB it is able to block the fusion of the phagosome within which it is existing with the lysosome which would destroy it. So it can continue existing and replicating within the immune cell designed to destroy it. After several weeks, the immune system somehow ramps up and, on stimulation with IFN-gamma, the macrophages become capable of killing M. tuberculosis by forming phagolysosomes and nitric oxide radicals. However unfortunately the hyper-activated macrophages secrete TNF which recruits multiple monocytes into the battle. These cells differentiate into epithelioid histiocytes which wall off the infected cells, but at the cost of significant inflammation and local damage.

Some other clinical examples:

  • Temporal arteritis
  • Hashimoto's thyroiditis
  • Symptoms of leprosy
  • Symptoms of tuberculosis
  • Coeliac disease
  • Graft-versus-host disease
  • Chronic transplant rejection

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