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- Dictionaryhypersensitivity/ˌhʌɪpəˌsɛnsɪˈtɪvɪti/
noun
- 1. extreme physical sensitivity to particular substances or conditions: "hypersensitivity to common chemicals"
- 2. a tendency to be easily hurt, worried, or offended: "hypersensitivity to criticism"
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Hypersensitivity (also called hypersensitivity reaction or intolerance) is an abnormal physiological condition in which there is an undesirable and adverse immune response to an antigen. It is an abnormality in the immune system that causes immune diseases including allergies and autoimmunity.
- Causes of Hypersensitivity
- Mechanism of Hypersensitivity
- Types of Hypersensitivity Reactions
- Hypersensitivity Type I, II, III and IV- Summary in Table Form
- Hypersensitivity Type I: Immediate Reaction
- Hypersensitivity Type II: Antibody-Mediated Cytotoxic Reaction
- Hypersensitivity Type III: Immune Complex-Mediated Reaction
- Hypersensitivity Type IV: Delayed-Type Hypersensitivity Reaction
- References
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Immune responses that are the cause of hypersensitivity diseases may be specific for antigens from different sources: 1. Autoimmunity: reactions against self antigens. 2. Reactions against microbes. 3. Reactions against non-microbial environmental antigens.
Hypersensitivity diseases are commonly classified according to the type of immune response and the effector mechanism responsible for cell and tissue injury. These mechanisms include some that are predominantly dependent on antibodies and others predominantly dependent on T cells, although a role for both humoral and cell-mediated immunity is often...
The Gell’s and Coombs’ classification of hypersensitivity reactions considers four types of reactions. Type I, II, and III reactions are basically mediated by antibodies with or without participation of the complement system; type IV reactions are cell-mediated. While in many pathological processes mechanisms classified in more than one of these ty...
Alternative Name Principle Primary Mediator Other components as mediators Reaction time Antigen Antigen origin Antibody Mechanism Complement activation Appearance Transfer with serum Desensitization Examples
Some antigens (allergens), such as insect venom, foods, pollen, and dust mite, can induce the formation of IgE antibodies in individuals with a corresponding predisposition. The IgE antibodies bind via Fc receptors to mast cells (sensitization). If the individual is re-exposed to the allergen, cross-linkage of the membrane-bound IgE occurs. This re...
The immunization of individuals to erythrocyte antigens during pregnancy is a typical example of a type II reaction. Children who inherit the RhD erythrocyte antigen from their father can induce immunization against the RhD+ antigen in their RhD-mother. Sensitization usually occurs at birth when fetal blood cells come into contact with the maternal...
Antibody-antigen complexes (immune complexes) can form during an immune response. Immune complexes can settle in vessel walls, the basement membrane of the lungs and/or kidneys, and in the joints (synovia). They can induce inflammatory processes in these structures by binding complement factors C3a and C5a (anaphylatoxins). A particular type III re...
Haptens are molecules of very small molecular weight (often < 1 kDa). They are too small to function as antigens, but they can penetrate the epidermis and bind to certain proteins in the skin (carrier proteins). Hapten-carrier complexes are bound by antigen-presenting cells of the skin (Langerhans cells), which then migrate to regional lymph nodes....
Lydyard, P.M., Whelan,A.,& Fanger,M.W. (2005).Immunology (2 ed.).London: BIOS Scientific Publishers.Owen, J. A., Punt, J., & Stranford, S. A. (2013). Kuby Immunology (7 ed.). New York: W.H. Freeman and Company.4% – http://semmelweis.hu/mikrobiologia/files/2014/05/hypersensitivity.pdf2% – https://basicmedicalkey.com/streptococcus-enterococcus-and-similar-organisms/Hypersensitivity is increased reactivity or sensitivity of the body to an antigen to which it has been previously exposed. It is classified into four types based on the mediators, mechanisms, and time of the immune response.
Mar 9, 2022 · A hypersensitivity reaction involves an abnormal response to a foreign body, or an antigen. The body can mount one of four different immune responses to this antigen. The antigen can be anything from a food to a medication. There are four different types of hypersensitivity reactions.
Oct 14, 2021 · Hypersensitivity reactions are extreme or unnecessary immune responses to antigens or allergens. Learn about the four types of hypersensitivity reactions, how they differ, and how to diagnose and treat them.
- Helen Millar
Jul 24, 2022 · Hypersensitivity Definition Hypersensitivity is the exaggerated immune response to protect the human from foreign bodies known as antigens. When the antigen is detected by the immune system, a hyperimmune response starts and the hypersensitivity reaction starts.
Allergy is one of a class of immune system responses that are termed hypersensitivity reactions. These are harmful immune responses that produce tissue injury and may cause serious disease. Hypersensitivity reactions were classified into four types by Coombs and Gell ( Fig. 12.2 ).
Apr 21, 2024 · Measurement of any wheal (a raised, itchy bump) and flare (redness) within minutes indicates a type I hypersensitivity, and the larger the wheal-flare reaction, the greater the patient’s sensitivity to the allergen.
