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hypersensitivity (hi″pәr-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 two types. The hypersensitivity states and resulting hypersensitivity reactions are usually subclassified by the Gell and Coombs classification. adj., hypersen´sitive., adj. 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 hypersensitivityDTH
hypersensitivity that takes hours or sometimes a few days to develop; this type can be transferred by lymphocytes but not
by serum and can be induced by most viral infections, many bacterial infections, all mycotic infections, and a few protozoal
infections. The scope of this term is sometimes expanded to cover all aspects of cell-mediated immunity, including allergic 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
may include any of various atopic allergy conditions (such as asthma, dermatitis, rhinitis, or urticaria) or sometimes anaphylaxis. Later exposure to the antigen triggers production and release of various mediators of hypersensitivity that act on other
cells to produce symptoms such as bronchospasm, edema, mucous secretions, and inflammation.
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