A hapten is a small molecule which can elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one which also does not elicit an immune response by itself. (Generally, only large molecules, infectious agents, or insoluble foreign matter can elicit an immune response in the body.)Once the body has generated antibodies to a hapten-carrier adduct, the small-molecule hapten may also be able to bind to the antibody, but it will usually not initiate an immune response; usually only the hapten-carrier adduct can do this. Sometimes the small-molecule hapten can even block immune response to the hapten-carrier adduct by preventing the adduct from binding to the antibody.

Examples of Haptens

A well known example of a hapten is urushiol, which is the toxin found in poison ivy. When absorbed through the skin from a poison ivy plant, urushiol undergoes oxidation in the skin cells to generate the actual hapten, a reactive molecule called a quinone which then reacts with skin proteins to form hapten adducts. Typically the first exposure only causes sensitization, in which there is a proliferation of B cells able to make antibody to the hapten adduct. After a second exposure later, the proliferated B cells can become activated, generating an immune reaction producing the typical blisters of poison ivy exposure.

Some haptens can induce autoimmune disease. An example is hydralazine, a blood pressure lowering drug which occasionally can produce drug-induced lupus erythematosus in certain individuals. This also appears to be the mechanism by which the anaesthetic gas halothane can cause a life-threatening hepatitis, as well as the mechanism by which penicillin-class drugs causes autoimmune hemolytic anemia.

Other haptens that are commonly used in molecular biology applications include fluorescein, biotin, digoxigenin, and dinitrophenol

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Look at other dictionaries:

  • hapten — hapten. См. полуантиген. (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.

  • hapten — HAPTÉN s. n. substanţă care, asociată cu o protidă, îi conferă calităţile unui antigen. (< fr. haptène) Trimis de raduborza, 15.09.2007. Sursa: MDN …   Dicționar Român

  • hapten — [hap′tēn΄hap′ten΄] n. [Ger < Gr haptein, to fasten, touch + Ger en, ENE] a compound which, when coupled with a protein or other molecule, can cause the formation of antibodies: also haptene [hap′tēn΄] haptenic [hap ten′ik] adj …   English World dictionary

  • hapten — Could be considered an isolated epitope: although a hapten (by definition) has an antibody directed against it, the hapten alone will not induce an immune response if injected into an animal, it must be conjugated to a carrier (usually a protein) …   Dictionary of molecular biology

  • hapten — /hap ten/, n. Immunol. a substance having a single antigenic determinant that can react with a previously existing antibody but cannot stimulate more antibody production unless combined with other molecules; a partial antigen. Also, haptene /hap… …   Universalium

  • Hapten — Haptene sind kleine organische Moleküle, wie z. B. Atrazin oder Digoxigenin. Sie gehören zur Gruppe der Antigene, unterscheiden sich jedoch von diesen dadurch, dass sie nicht alleine in der Lage sind, eine Immunreaktion hervorzurufen. Dies ist… …   Deutsch Wikipedia

  • hapten — A molecule that is incapable, alone, of causing the production of antibodies but can, however, combine with a larger antigenic molecule called a carrier. A h. carrier complex can stimulate production of antibodies, some of which combine with the… …   Medical dictionary

  • hapten — /ˈhæptən/ (say haptuhn) noun a small molecule which cannot by itself elicit an immune response but which needs to be attached to a larger carrier in order to do so. {German hapten, from Greek haptein to fasten} …   Australian-English dictionary

  • hapten — noun Etymology: German, from Greek haptein to fasten Date: 1921 a small separable part of an antigen that reacts specifically with an antibody but is incapable of stimulating antibody production except in combination with a carrier protein… …   New Collegiate Dictionary

  • hapten — (hap ten) A molecule not immunogenic by itself but that, when coupled to a macromolecular carrier, can elicit antibodies directed against itself …   Dictionary of microbiology

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