Hypersensitivities
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Hypersensitivities
Hypersensitivities (pronounced: hi-per-sen-si-tiv-i-tees) are a set of conditions where the immune system reacts abnormally to a foreign substance. The term originates from the Greek words "hyper" meaning over, and "sensitivity" meaning a state of being sensitive.
Types of Hypersensitivities
There are four types of hypersensitivities, each with its own unique characteristics and triggers:
- Type I Hypersensitivity (also known as immediate hypersensitivity) typically occurs within minutes of exposure to an allergen and can lead to conditions such as asthma, allergic rhinitis, and anaphylaxis.
- Type II Hypersensitivity (or cytotoxic hypersensitivity) involves the destruction of host cells by the immune system, often leading to conditions like hemolytic anemia and Goodpasture syndrome.
- Type III Hypersensitivity (or immune complex hypersensitivity) is characterized by the formation of immune complexes that can deposit in various tissues, causing inflammation and damage.
- Type IV Hypersensitivity (or delayed-type hypersensitivity) is mediated by T cells and typically takes 48-72 hours to develop. It is involved in many autoimmune and infectious diseases, including tuberculosis and contact dermatitis.
Related Terms
- Allergy: A hypersensitivity reaction to a particular allergen; symptoms can vary greatly in severity.
- Autoimmunity: A misdirected immune response that occurs when the immune system goes awry and attacks the body itself.
- Immunology: The branch of medicine and biology concerned with immunity.
- Antigen: A substance that induces a immune response in the body, especially the production of antibodies.
See Also
External links
- Medical encyclopedia article on Hypersensitivities
- Wikipedia's article - Hypersensitivities
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