| Type III hypersensitivity | |
|---|---|
| Classification and external resources | |
 Immune complex |
|
| MeSH | D007105 |
| 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 III hypersensitivity occurs when antigens and antibodies (IgG or IgM)[1] are present in roughly equal amounts, causing extensive cross-linking.
Presentation
It is characterized by soluble antigens that are not bound to cell surfaces (which is the case in type II hypersensitivity). When these antigens bind antibodies, immune complexes of different sizes form[2]. Large complexes can be cleared by macrophages but they have difficulty binding to small immune complexes for clearance. These immune complexes insert themselves into small blood vessels, joints, and glomeruli, causing symptoms.
They deposit in tissues and induce an inflammatory response,[3] and can cause damage wherever they precipitate.
The reaction can take hours, days, or even weeks to develop.
Examples
Some clinical examples:
| Disease | Target antigen | Main effects | |
|---|---|---|---|
| Systemic lupus erythematosus | Nuclear antigens |
|
|
| Post-streptococcal glomerulonephritis | Streptococcal cell wall antigens |
|
|
| Polyarteritis nodosa | Hepatitis B virus antigen |
|
|
| Reactive arthritis | Several bacterial antigens |
|
|
| Serum sickness | Various |
|
|
| Arthus reaction | Various |
|
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| Unless else specified in boxes, then ref is: [4] | |||
Other examples are:
- Rheumatoid arthritis
- Subacute bacterial endocarditis[5]
- Symptoms of malaria
- Farmer's lung (Arthus-type reaction)
References
- ^ "The Adaptive Immune System: Type III Immediate Hypersensitivity". http://student.ccbcmd.edu/courses/bio141/lecguide/unit5/hypersensitivity/type3/type3.html. Retrieved 2009-01-08.
- ^ "Hypersensitivity reactions". http://pathmicro.med.sc.edu/ghaffar/hyper00.htm. Retrieved 2008-09-26.
- ^ "Chapter 19". http://compepid.tuskegee.edu/syllabi/pathobiology/microbiology/micro201/chapter19.html. Retrieved 2009-01-08.
- ^ Table 5-3 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson. Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7. 8th edition.
- ^ "Definition: immune complex disease from Online Medical Dictionary". http://128.240.24.212/cgi-bin/omd?type+III+hypersensitivity+reaction.
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