Antibody
hideAntibodies (also known as immunoglobulins, abbreviated Ig) are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. They are typically made of basic structural units—each with two large heavy chains and two small light chains—to form, for example, monomers with one unit, dimers with two units or pentamers with five units. Antibodies are produced by a kind of white blood cell called a plasma cell. There are several different types of antibody heavy chains, and several different kinds of antibodies, which are grouped into different isotypes based on which heavy chain they possess. Five different antibody isotypes are known in mammals, which perform different roles, and help direct the appropriate immune response for each different type of foreign object they encounter.
Although the general structure of all antibodies is very similar, a small region at the tip of the protein is extremely variable, allowing millions of antibodies with slightly different tip structures, or antigen binding sites, to exist. This region is known as the hypervariable region. Each of these variants can bind to a different target, known as an antigen. This huge diversity of antibodies allows the immune system to recognize an equally wide diversity of antigens. The unique part of the antigen recognized by an antibody is called an epitope. These epitopes bind with their antibody in a highly specific interaction, called induced fit, that allows antibodies to identify and bind only their unique antigen in the midst of the millions of different molecules that make up an organism. Recognition of an antigen by an antibody tags it for attack by other parts of the immune system. Antibodies can also neutralize targets directly by, for example, binding to a part of a pathogen that it needs to cause an infection.
The large and diverse population of antibodies is generated by random combinations of a set of gene segments that encode different antigen binding sites (or paratopes), followed by random mutations in this area of the antibody gene, which create further diversity. Antibody genes also re-organize in a process called class switching that changes the base of the heavy chain to another, creating a different isotype of the antibody that retains the antigen specific variable region. This allows a single antibody to be used by several different parts of the immune system. Production of antibodies is the main function of the humoral immune system.
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News tagged with antibodies
How eating red meat can spur cancer progression
Nov 13, 2008 |
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Researchers at the University of California, San Diego School of Medicine, led by Ajit Varki, M.D., have shown a new mechanism for how human consumption of red meat and milk products could contribute to the increased risk ...
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Medicine & Health / HIV & AIDS
Sep 04, 2008 |
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Scientists from the Gladstone Institute of Virology and Immunology (GIVI) and the National Institutes of Allergy and Infectious Diseases (NIAID) have identified a gene that may influence the production of antibodies that ...
Scientists engineer new type of vaccination that provides instant immunity
Mar 02, 2009 |
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The experiments, thus far performed only in mice, appear to overcome a major drawback of vaccinations - the lag time of days, or even weeks, that it normally takes for immunity to build against a pathogen. This new method ...
1918 flu antibodies resurrected from elderly survivors
Aug 17, 2008 |
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Ninety years after the sweeping destruction of the 1918 flu pandemic, researchers at Monroe Carell Jr. Children's Hospital at Vanderbilt have recovered antibodies to the virus – from elderly survivors of the original outbreak.
Vaccine being developed to help smokers quit
Medicine & Health / Medications
Nov 20, 2009 |
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(PhysOrg.com) -- Glaxo-SmithKline has joined forces with Nabi Pharmaceuticals to produce a vaccine to help smokers give up their addiction permanently.
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Medicine & Health / HIV & AIDS
Oct 09, 2008 |
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(PhysOrg.com) -- Scientists have identified the very first antibodies to appear in the wake of HIV infection and have concluded that they are virtually impotent in mounting a meaningful defense against the invading virus.
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Nov 05, 2009 |
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Some 25 years after the AIDS epidemic spawned a worldwide search for an effective vaccine against the human immunodeficiency virus (HIV), progress in the field seems to have effectively become stalled. The ...
Scientists identify human monoclonal antibodies effective against bird and seasonal flu viruses
Biology /
Feb 22, 2009 |
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Researchers at the Dana-Farber Cancer Institute, Burnham Institute for Medical Research and the Centers for Disease Control and Prevention have reported the identification of human monoclonal antibodies (mAb) that neutralize ...
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(PhysOrg.com) -- Could Wisconsin's signature product – milk – hold the key to one of the biggest problems in organ transplantation?
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New research suggests that monoclonal antibody therapy of cancer can be improved to be much more powerful than it is today, says a researcher at Georgetown University Medical Center's Lombardi Comprehensive Cancer Center ...
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By studying the intricate mechanisms at work in protein production, a Princeton-led team has discovered why certain kinds of antibiotics are so effective. In doing so, they also have discovered how one protein ...
Chemists say antibody surrogates are just a 'click' away
Jul 09, 2009 |
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Chemists at the California Institute of Technology and the Scripps Research Institute have developed an innovative technique to create cheap but highly stable chemicals that have the potential to take the place of the antibodies ...
Scientists solve failed vaccine mystery
Dec 15, 2008 |
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Research led by Johns Hopkins Children's Center scientists has figured out why a respiratory syncytial virus vaccine used in 1966 to inoculate children against the infection instead caused severe respiratory disease and effectively ...
