immunology Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see there ...

, an idiotype is a shared characteristic between a group of

immunoglobulin An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

T-cell receptor The T-cell receptor (TCR) is a protein complex found on the surface of T cells, or T lymphocytes, that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules. The binding b ...

(TCR) molecules based upon the

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

binding specificity and therefore structure of their

variable region An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

. The variable region of antigen receptors of

T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

s (TCRs) and

B cell B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or ...

s (immunoglobulins) contain

complementarity-determining region Complementarity-determining regions (CDRs) are part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen. A set of CDRs co ...

s (CDRs) with unique

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

sequences. They define the surface and properties of the variable region, determining the antigen specificity and therefore the idiotope of the molecule. Immunoglobulins or TCRs with a shared

idiotope In immunology, an idiotope is the unique set of antigenic determinants (epitopes) of the variable portion of an antibody. In some cases it can be the actual antigen-binding site, and in some cases it may comprise variable region sequences outside ...

are the same idiotype. Antibody idiotype is determined by: *Gene rearrangement *Junctional diversity *P-nucleotides (palindromic nucleotides at sites of single-strand breaks) *N-nucleotides *Somatic hypermutations

Etymology and usage

The word idiotype comes from two Greek roots, ''idio'' meaning 'private, distinctive, peculiar' and ''typos'' meaning 'mark.' Thus, idiotype describes the distinctive sequence and region that makes any immunoglobulin/TCR unique from others of the same type which is its variable region. The term "idiotype" is sometimes used to describe the collection of multiple idiotopes, and therefore overall antigen binding capacity, possessed by an antibody. The word "idiotype" became influential in immunology when

Niels Jerne Niels is a male given name, equivalent to Nicholas, which is common in Denmark, Belgium, Norway (formerly) and the Netherlands. The Norwegian and Swedish variant is Nils. The name is a developed short form of Nicholas or Greek Nicolaos after Saint ...

formulated his

immune network theory The immune network theory is a theory of how the adaptive immune system works, that has been developed since 1974 mainly by Niels Jerne and Geoffrey W. Hoffmann. The theory states that the immune system is an interacting network of lymphocytes and m ...

. Jerne was awarded the

Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...

in 1984 largely for being the father of immune network theory. He defined idiotype as the set of epitopes on the V region of an antibody molecule, where

epitope An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The p ...

means an antigenic determinant. He also defined the "

paratope In immunology, a paratope, also known as an antigen-binding site, is the part of an antibody which recognizes and binds to an antigen. It is a small region at the tip of the antibody's antigen-binding fragment and contains parts of the antibody' ...

" to be that part of an antibody variable region that binds to an antigen. The best developed version of immune network theory is called the symmetrical network theory, in which the distinction between idiotype and paratope plays no role.

External links

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Medical University of South Carolina The Medical University of South Carolina (MUSC) is a public medical school in South Carolina. It opened in 1824 in Charleston as a small private college aimed at training physicians and has since established hospitals and medical facilities acr ...

Overview
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Southern Illinois University Carbondale Southern Illinois University (SIU or SIUC) is a public research university in Carbondale, Illinois. Founded in 1869, SIU is the oldest and flagship campus of the Southern Illinois University system. The university enrolls students from all 50 s ...

{{Immune system Immune system

Etymology and usage

See also

External links