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Related to Type I hypersensitivity: immediate hypersensitivity reaction


a state of altered reactivity in which the body reacts with an exaggerated immune response to a foreign agent; anaphylaxis and allergy are forms of hypersensitivity. The hypersensitivity states and resulting hypersensitivity reactions are usually subclassified by the Gell and Coombs classification. adj., adj hypersen´sitive.
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.


1. Abnormal sensitivity, a condition in which there is an exaggerated response by the body to the stimulus of a foreign agent.
2. In endocrinology, an excessive target tissue response to a hormone. Synonym(s): hormone hypersensitivity


Immunology An abnormal immune response that may be immediate–due to antibodies of the IgE class, or delayed–due to cell-mediated immunity. See Cold hypersensitivity, Immediate hypersensitivity Neurology Exaggerated sensitivity An ↑in a person's sensitivity to light, sound, smell, taste, touch, temperature, balance, and even emotional issues, which may be linked to anxiety and panic disorders.


Abnormal sensitivity, a condition in which there is an exaggerated response by the body to the stimulus of a foreign agent.
See: allergy


An allergic state in which more severe tissue reactions occur on a second or subsequent exposure to an ANTIGEN than on the first exposure. A particular group of antibodies (IgE) is involved in many hypersensitivity reactions.


the process of localized plant cell death that occurs immediately after entry of a cell by a plant pathogen. Such a reaction can act as a host-resistance mechanism since the cell death often prevents further growth of biotrophic pathogens, e.g. powdery mildews or rusts.


After the body's immune system attacks an outside invader (such as organic dust or a fungus) many times, exposure to even a tiny amount of this allergen can provoke a strong inflammatory response.


An excessive reaction, local or systemic, or inappropriate immune response to an antigen. Four types of immune responses are usually described, but the main reaction involving the eyes is type 1. They are also called allergic reactions types 1-4.
type 1 hypersensitivity An immediate, abnormal reaction occurring when an antigen reacts with an antibody (e.g. immunoglobulin E (IgE)) attached to a mast cell or basophil. This leads to the release of specific chemical mediators of allergy (e.g. histamine) that react with target organs throughout the body. Systemic signs include: itching, lacrimation, skin rash and possibly haemodynamic collapse and shock. Allergic conjunctivitis is an example of this type of hypersensitivity.
Type 2 h . (cytotoxic h.) is caused by an interaction of antibody and antigens on cell surfaces. Examples: Graves' disease, myasthenia gravis. Type 3 h. (immune-complex mediated h.) is mediated by a combination of antigen-antibody. Example: systemic lupus erythematosus. Type 4 h. (T cell-mediated h.) is a delayed reaction (several days to develop) mediated by T lymphocytes. Example: rheumatoid arthritis. See antihistamine; mast cell stabilizers.


In endocrinology, an excessive target tissue response to a hormone.

Patient discussion about hypersensitivity

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:

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:

More discussions about hypersensitivity
References in periodicals archive ?
The relevance between the occurrence of each symptom (inclusion criteria) and detection of type I hypersensitivity in the study "Incidence of lidocaine allergy in dentists" conducted in 2012-2016 Type I hypersensitivity Symptom [n (%)] p ([chi square]) no yes Urticaria 0.03 no 53 (60.92) 2 (15.38) yes 34 (39.08) 11 (84.62) Angioedema 0 no 60 (68.97) 0 (0) yes 27 (31.03) 13 (100) Rhinitis 0 no 66 (75.86) 3(23.08) yes 21 (24.14) 10 (76.92) Dyspnea 1 no 57 (65.52) 8 (61.54) yes 30 (34.48) 5 (38.46) Nausea 0.616 no 79 (90.8) 11 (84.62) yes 8 (9.2) 2 (15.38) Vertigo 1 no 22 (25.29) 3(23.08) yes 65 (74.71) 10 (76.92) Fainting 0.707 no 72 (82.76) 10 (76.92) yes 15 (17.24) 3(23.08) Table 3.
Skin Reactions to Latex Reaction Response Irritation Contact Dermatitis red, chapped hands (rapid--minutes to hours) blistering burning or itching dry skin reaction limited to contact area Allergic Contact Dermatitis (ACD)(*) eczema Type IV Hypersensitivity Reaction severe itching (delayed--6 to 48 hours) vesicles/blisters dryness cracking crusting desquamation reaction may extend beyond glove area (up the arm) (*) appearance similar to irritant contact dermatitis; difference is the extent (within or beyond glove border) of the reaction (*) chemical sensitivity falls within this type of reaction Immediate Allergic Urticaria itching Type I Hypersensitivity Reaction urticaria (immediate-minutes to 1 hour) erythema edema pruritis swelling Skin reactions can be affected by other factors.
A latex-free environment should be implemented, meaning no use or direct contact with latex gloves or devices.[46] Type I hypersensitivity is very serious, and can result in anaphylaxis with minimal exposure.

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