delayed hypersensitivity


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Related to delayed hypersensitivity: Delayed Hypersensitivity Skin Test

hypersensitivity

 [hi″per-sen″sĭ-tiv´ĭ-te]
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.

de·layed hy·per·sen·si·tiv·i·ty

1. Synonym(s): cell-mediated immunity
2. Synonym(s): delayed reaction
3. a cell-mediated response that occurs in immune people peaking at 24-48 hours after challenge with the same antigen used in an initial challenge. The interaction of T-helper 1 (Th-1) lymphocytes with MHC class II positive antigen-presenting cells initiates the response. This interaction induces the Th-1s and macrophages at the site to secrete cytokines, which are the major factors in the reaction. Called tuberculin-type hypersensitivity.

delayed hypersensitivity

An allergic reaction occurring two to three days after the antigen contact and mediated by CYTOKINE release from sensitized T cells (T LYMPHOCYTES).

de·layed hy·per·sen·si·ti·vi·ty

(dē-lād hīpĕr-sensi-tivi-tē)
A cell-mediated response that occurs in immune people peaking at 24-48 hours after challenge with the same antigen used in an initial challenge.
References in periodicals archive ?
This inhibition of migration seems characteristic of cells from animals with delayed hypersensitivity since exudates cells obtained from non-hypersensitive animals immunized to produce only circulating antibody are not inhibited by antigen.
Mantoux testing elicits a delayed hypersensitivity reaction to a previously sensitized antigen (a T-lymphocyte function), and it is generally accepted as a valid in vivo indicator of a patient's level of cell-mediated immunity.
This type of delayed hypersensitivity reaction would also not be expected to predispose to anaphylaxis.
Two types of hypersensitivity are described with LAs--the relatively more common contact delayed hypersensitivity, mainly related to ester-LAs, and the less common immediate hypersensitivity associated with ester-LAs and exceptionally with amide-LAs.
There were no statistically significant relationships between peak antibody titer and the subject's sex or delayed hypersensitivity response to an intradermal Candida challenge.
In lower concentrations, eugenol can act as a contact allergen evoking a localized delayed hypersensitivity reaction.
The bad news: Type IV delayed hypersensitivity to other chemicals found in gloves-or that readily permeate gloves-is on the rise, Dr.
for evaluation of 100 foods for delayed hypersensitivity utilizing their multi-pathway method.
A photosensitivity reaction, occurring mainly on sun-exposed areas, is a delayed hypersensitivity reaction reflecting direct cellular damage produced by the photochemical reaction between a chemical photosensitizer and the appropriate radiation on the skin and is independent of dose and duration of exposure (4).
(2), (3) For those with food allergies that are not IgE-mediated and associated with delayed hypersensitivity reactions, estimates are more difficult to determine.

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