Idiotopes

Idiotopes

An idiotope is the unique set of antigenic determinants of the variable portion of an antibody.cite web |url=http://www.mercksource.com/pp/us/cns/cns_hl_dorlands.jspzQzpgzEzzSzppdocszSzuszSzcommonzSzdorlandszSzdorlandzSzdmd_i_01zPzhtm |title=Dorlands Medical Dictionary |accessdate=2008-03-23 |format= |work=] In some cases it can be the actual antigen-binding site, and in some cases it may comprise variable region sequences outside of the antigen-binding site on the antibody itself. Thus each antibody would have multiple idiotopes; and the sum of these individual idiotopes is termed the idiotype of the antibody.

Idiotopes contrast with allotopes, which are non-varying structures on the Fc receptor.cite web |url=http://www.mercksource.com/pp/us/cns/cns_hl_dorlands.jspzQzpgzEzzSzppdocszSzuszSzcommonzSzdorlandszSzdorlandzSzdmd_a_25zPzhtm |title=Dorlands Medical Dictionary |accessdate=2008-03-23 |format= |work=]

If a separate antibody is produced that has specific binding capabilities to an idiotope of the previously described antibody, it is said to be an "anti-idiotypic antibody". If such is the case, the anti-idiotypic antibodies will be able to bind to the B lymphocyte receptor for the original antigen and inhibit the immune response to that antigen.

This type of regulation was proposed by Niels Jerne in 1974. He termed it the "Network Hypothesis". This type of B lymphocyte regulation may be partially responsible for preventing an immune response from getting out of control, which would elicit damage to host tissue or even cause an autoimmune diseased state.

Because of the resemblance of anti-idiotypic antibodies to the original antigen, vaccine studies have been performed. These types of vaccines are called "idiotypic vaccines". None are produced commercially to date.

References


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  • Anti-idiotypic — vaccines comprise antibodies that have three dimensional immunogenic regions, designated idiotopes, that consist of protein sequences that bind to cell receptors. Idiotopes are aggregated into idiotypes specific of their target antigen.… …   Wikipedia

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  • idiotope — An antigenic determinant (epitope) unique to a single clone of cells and located in the variable region of the immunoglobulin product of that clone or to the T cell receptor. The idiotope forms part of the antigen binding site. Any single… …   Dictionary of molecular biology

  • idiotype — The antigenic specificities defined by the unique sequences (idiotopes) of the antigen combining site. Thus anti idiotype antibodies combine with those specific sequences, may block immunological reactions, and may resemble the epitope to which… …   Dictionary of molecular biology

  • idiotope — Single antigenic determinant of an idiotype. SEE ALSO: idiotypic antigenic determinant. SYN: idiotypic antigenic determinant. [idio + tope] set of idiotopes (antigenic determinants) of either the immunoglobulin or T cell receptor v …   Medical dictionary

  • OUDIN (J.) — Jacques OUDIN 1908 1985 Le nom de Jacques Oudin, décédé à Paris le 15 octobre 1985, est indéfectiblement lié à trois découvertes parmi les plus marquantes de l’immunologie contemporaine: l’analyse immunochimique en milieu gélifié, les… …   Encyclopédie Universelle

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