hypersensitivity
[hi″per-sen″sĭ-tiv´ĭ-te] contact hypersensitivity that produced by contact of the skin with a chemical substance having the properties of an antigen or hapten.
delayed hypersensitivity (DH) (delayed type hypersensitivity (DTH)) the type of hypersensitivity exemplified by the tuberculin reaction, which (as opposed to immediate hypersensitivity) takes 12 to 48 hours to develop and which can be transferred by lymphocytes but not by serum. Delayed hypersensitivity can be induced by most viral infections, many bacterial infections, all mycotic infections, and a few protozoal infections (leishmaniasis and toxoplasmosis). The scope of the term is sometimes expanded to cover all aspects of cell-mediated immunity including contact dermatitis, granulomatous reactions, and allograft rejection.
immediate hypersensitivity antibody-mediated hypersensitivity occurring within minutes when a sensitized individual is exposed to antigen; clinical manifestations include systemic anaphylaxis and atopic allergy (allergic rhinitis, asthma, dermatitis, urticaria, and angioedema). The first exposure to the antigen induces the production of IgE antibodies (cytotropic antibodies, reagin) that bind to receptors on mast cells and basophils. Subsequent exposure to the antigen triggers production and release of a diverse array of mediators of hypersensitivity that act on other cells producing symptoms such as bronchospasm, edema, mucous secretion, and inflammation.
hypersensitivity reaction the exaggerated or inappropriate immune response occurring in
hypersensitivity, in response to a substance either foreign or perceived as foreign and resulting in local or general tissue damage. Such reactions are usually classified as types I–IV on the basis of the
Gell and Coombs classification.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
al·ler·gic re·ac·tion
a local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and sensitized; immunologic mechanisms gives rise to inflammation or tissue damage. Allergic reactions are classified into four major types: type I, anaphylactic and IgE dependent; type II, cytotoxic; type III, immune-complex mediated; type IV, cell mediated (delayed).
Farlex Partner Medical Dictionary © Farlex 2012
al·ler·gic re·ac·tion
(ă-lĕr'jik rē-ak'shŭn) Local or general reaction of an organism after contact with a specific allergen to which it has been previously exposed and sensitized.
Synonym(s):
hypersensitivity reaction.
Medical Dictionary for the Dental Professions © Farlex 2012
Patient discussion about hypersensitivity reaction
Q. ALLERGIES what are they,who gets them,are they caused by pollen and food?
A. Allergy is the exaggerated and out-of-place reaction of the immune system to external substances or stimuli that are not harmful to the body, so the reaction actually damages the body instead of helping it.
The may be pollen and foods, as well as insect stings, drugs and almost any other substances.
You may read more here:
www.nlm.nih.gov/medlineplus/allergy.html
http://www.mayoclinic.com/health/allergy/AA99999
Q. what is the most common allergy? is it dust allergy?
A. thanks, I've heard of a new allergy treatment and trying to learn some more about the different kinds...
Q. what are the symptoms of Allergy?
A. from you question i understand that you think you might developed an allergy. so here is a web page with couple of videos explaining about allergies:
http://www.healthline.com/video/allergies
More discussions about hypersensitivity reactionThis content is provided by iMedix and is subject to iMedix Terms. The Questions and Answers are not endorsed or recommended and are made available by patients, not doctors.