In immunology, a state of excessive and potentially damaging immune responsiveness as a result of previous exposure to antigen. If the hypersensitivity is of the immediate type (antibody-mediated), then the response occurs in minutes; in delayed hypersensitivity the response takes much longer (about 24h) and is mediated by primed T-cells. Hypersensitivity responses are not simply divisible into the two types, and it is now more common to subdivide immediate responses into types I, II, and III, the delayed response being of type IV. Type I responses involve antigen reacting with IgE fixed to cells (usually mast cells) and are characterized by histamine release; anaphylactic responses and urticaria are of this type. In type II responses circulating antibody reacts with cell surface or cell-bound antigen, and if complement fixation occurs, cytolysis may follow. In type III reactions immune complexes are formed in solution and lead to damage (serum sickness, glomerulonephritis, Arthus reaction). Delayed-type responses of Type IV involve primed lymphocytes reacting with antigen and lead to formation of a lymphocyte-macrophage granuloma without involvement of circulating antibody.

Dictionary of molecular biology. 2004.

Look at other dictionaries:

  • hypersensitivity — hypersensitivity. См. гиперчувствительность. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Hypersensitivity — NOTOC Infobox Disease Name = PAGENAME Caption = DiseasesDB = 28827 ICD10 = ICD10|T|78|4|t|66 ICD9 = ICD9|995.3 ICDO = OMIM = MedlinePlus = eMedicineSubj = eMedicineTopic = MeshID = D006967 Hypersensitivity (also called hypersensitivity reaction)… …   Wikipedia

  • hypersensitivity — Abnormal sensitivity, a condition in which there is an exaggerated response by the body to the stimulus of a foreign agent. See allergy. contact h. 1. SYN: contact dermatitis. 2. SYN: delayed reaction. delayed h. 1 …   Medical dictionary

  • hypersensitivity — See hypersensitiveness. * * *       acquired bodily state in which the reaction to a stimulus (e.g., a substance causing allergy or a physical agent such as light) is unusually prompt or excessive. The term hypersensitivity is often used as a… …   Universalium

  • hypersensitivity — superjautrumas statusas T sritis augalininkystė apibrėžtis Labai greitas augalo ląstelių su patekusiu virusu arba grybų hifais žuvimas, dėl kurio patogenas izoliuojamas ir negali toliau augale plisti. atitikmenys: angl. hypersensitivity rus.… …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • hypersensitivity — noun 1. pathological sensitivity • Derivationally related forms: ↑hypersensitive • Hypernyms: ↑sensitivity, ↑predisposition • Hyponyms: ↑cryesthesia, ↑cryaesthesia, ↑ …   Useful english dictionary

  • hypersensitivity — noun see hypersensitive …   New Collegiate Dictionary

  • hypersensitivity — (hi per sen si tiv i te) A condition of increased immune sensitivity in which the body reacts to an antigen with an exaggerated immune response that usually harms the individual. Also termed an allergy …   Dictionary of microbiology

  • hypersensitivity — noun any heightened immune response to an antigen; an allergy See Also: hypersensitive …   Wiktionary

  • hypersensitivity — Synonyms and related words: allergy, anaphylaxis, considerateness, delicacy, empathy, exquisiteness, fineness, hairsplitting, hypercriticism, hyperesthesia, hyperpathia, hypersensitiveness, identification, irritability, morbid sensibility,… …   Moby Thesaurus

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