hypersensitivity reaction

a reaction in which the body mounts an exaggerated or inappropriate immune response to a substance either foreign or perceived as foreign, 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 (q.v.).

Medical dictionary. 2011.

Look at other dictionaries:

  • hypersensitivity reaction — noun an inappropriate and excessive reaction to an allergen (as pollen or dust or animal hair or certain foods); severity ranges from mild allergy to severe systemic reactions leading to anaphylactic shock • Hypernyms: ↑hypersensitivity •… …   Useful english dictionary

  • Type V hypersensitivity reaction — A Type V hypersensitivity reaction occurs when IgG class antibodies directed towards cell surface antigens have a stimulating effect on their target.Grave s disease is an example of this type of hypersensitivity reaction. This disease is also… …   Wikipedia

  • delayed hypersensitivity reaction — a reaction of cell mediated immunity, named in contrast to immediate hypersensitivity reactions because its onset is 24 to 72 hours after the antigenic challenge; the term is usually used to denote the subset of type IV hypersensitivity reactions …   Medical dictionary

  • immediate hypersensitivity reaction — 1. type I hypersensitivity r. 2. occasionally, any hypersensitivity reaction mediated by antibodies and developing rapidly, generally in minutes to hours (i.e., type I, II, or III hypersensitivity r.), as distinguished from those mediated by T… …   Medical dictionary

  • antibody-mediated hypersensitivity reaction — 1. type II hypersensitivity r. 2. occasionally, any hypersensitivity reaction in which antibodies are the primary mediators, as contrasted with those mediated by T lymphocytes; included are types I, II, and III hypersensitivity r s …   Medical dictionary

  • antibody-mediated cytotoxic hypersensitivity reaction — type II hypersensitivity r …   Medical dictionary

  • cell-mediated hypersensitivity reaction — type IV hypersensitivity r …   Medical dictionary

  • cytotoxic hypersensitivity reaction — type II hypersensitivity r …   Medical dictionary

  • immune complex–mediated hypersensitivity reaction — type III hypersensitivity r …   Medical dictionary

  • T cell–mediated hypersensitivity reaction — type IV hypersensitivity r …   Medical dictionary

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