antibody

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antibody,

protein produced by the immune system (see immunityimmunity,
ability of an organism to resist disease by identifying and destroying foreign substances or organisms. Although all animals have some immune capabilities, little is known about nonmammalian immunity.
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) in response to the presence in the body of antigens: foreign proteins or polysaccharides such as bacteria, bacterial toxinstoxin,
poison produced by living organisms. Toxins are classified as either exotoxins or endotoxins. Exotoxins are a diverse group of soluble proteins released into the surrounding tissue by living bacterial cells. Exotoxins have specific reaction sites in the host; e.g.
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, viruses, or other cells or proteins. Such antigens are capable of inflicting damage by chemically combining with natural substances in the body and disrupting the body's processes. The body contains hundreds of thousands of different white blood cells called B lymphocytes, each capable of producing one type of antibody and each bearing sites on its membrane that will bind with a specific antigen. When such a binding occurs, it triggers the B lymphocyte to reproduce itself, forming a cloneclone,
group of organisms, all of which are descended from a single individual through asexual reproduction, as in a pure cell culture of bacteria. Except for changes in the hereditary material that come about by mutation, all members of a clone are genetically identical.
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 that manufactures vast amounts of its antibody.

The antibody molecule is composed of four polypeptide chains (see peptidepeptide,
organic compound composed of amino acids linked together chemically by peptide bonds. The peptide bond always involves a single covalent link between the α-carboxyl (oxygen-bearing carbon) of one amino acid and the amino nitrogen of a second amino acid.
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)—two identical light chains and two identical heavy chains—joined by disulfide bridges. The light chains have a variable portion that is different in each type of antibody and is the active portion of the molecule that binds with the specific antigen. Antibodies combine with some antigens, such as bacterial toxins, and neutralize their effect; they remove other substances from circulation in body fluids; they bind certain antigens together, a process known as agglutination; and they activate complement, blood serum proteins that cause the destruction of invading cells.

See also monoclonal antibodymonoclonal antibody,
an antibody that is mass produced in the laboratory from a single clone and that recognizes only one antigen. Monoclonal antibodies are typically made by fusing a normally short-lived, antibody-producing B cell (see immunity) to a fast-growing cell, such as
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.

Antibody

A protein found principally in blood serum and characterized by a specific reactivity with the corresponding antigen. Antibodies are important in resistance against disease, in allergy, and in blood transfusions, and can be utilized in laboratory tests for the detection of antigens or the estimation of immune status.

Antibodies are normally absent at birth unless derived passively from the mother through the placenta or colostrum. In time, certain antibodies appear in response to environmental antigens. Antibodies are also induced by artificial immunization with vaccines or following natural infections. The resulting antibody level declines over a period of months, but rapidly increases following renewed contact with specific antigen, even after a lapse of years. This is known as an anamnestic or booster response. See Allergy, Blood groups, Hypersensitivity, Isoantigen, Vaccination

Antibody reactivity results in precipitation of soluble antigens, agglutination of particulate antigens, increased phagocytosis of bacteria, neutralization of toxins, and dissolution of bacterial or other cells specifically sensitive to their action; the antibodies so revealed are termed precipitins, agglutinins, opsonins, antitoxins, and lysins. One antibody may give many such reactions, depending on conditions, so these classifications are not unique or exclusive.

Three principal groups (IgG, IgM, IgA) and two minor groups (IgD, IgE) of antibodies are recognized. These all form part of the wider classification of immunoglobulins. Antibody diversity is generated by amino acid substitutions that result in unique antigen-binding structures. See Cellular Immunology, Immunoglobulin

The development of the technology for producing monoclonal antibodies, which can bind to specific sites on target antigens, revolutionized the uses of antibodies in biology and medicine. Unfortunately, almost all monoclonal antibodies originate in mice, and the murine immunoglobulin serves as an antigen, frequently acting immunogenic in human recipients. See Antigen, Monoclonal antibodies

antibody

[′an·tə‚bäd·ē]
(immunology)
A protein, found principally in blood serum, originating either normally or in response to an antigen and characterized by a specific reactivity with its complementary antigen. Also known as immune body.

antibody

any of various proteins produced in the blood in response to the presence of an antigen. By becoming attached to antigens on infectious organisms antibodies can render them harmless or cause them to be destroyed
References in periodicals archive ?
29%) developed protective antibody titer after receiving their 4th dose of vaccine compared with other trials done by Goyal et al.
The minimal protective antibody amount has not been defined, but several lines of evidence suggest that it is <10 mIU/mL.
Vaccine should be offered to high-risk persons up to and even after influenza activity is documented in a community [3]; following vaccination, 1-2 weeks are required for the development of protective antibody titers.
These injections reduce the amount of IgE antibodies in the blood and cause the body to make a protective antibody called IgG.
The goal of the project is to create carbohydrate immunogens capable of stimulating protective antibody responses to HIV.
Protective antibody levels, which were determined in rabbit and monkey studies, were used to predict efficacy in humans based on an assessment of the extent of antibody response achieved in human study participants.
A study that followed up children aged 5 years who had received a meningococcal group B vaccine as infants in an earlier study determined that protective antibody levels against the strains covered by the vaccine dropped over time, with variations depending on the strains and vaccine dose schedules, the investigators reported.
00 TCID50 induced more than 50% percent inhibition (PI) that is considered as protective antibody titer.
Biotechnology company GeoVax Labs Inc (OTCQB:GOVX) revealed on Thursday the receipt of a Notice of Award from the US National Institutes of Health for a Small Business Innovative Research (SBIR) grant entitled "Enhancing Protective Antibody Responses for a GM-CSF Adjuvanted HIV Vaccine.
Pretravel titers of [greater than or equal to] 40 for [greater than or equal to] 1 influenza viruses were defined as protective antibody titers.
The study led by Octavio Ramilo, MD, chief of Infectious Diseases and an investigator in the Center for Vaccines and Immunity at Nationwide Children's Hospital and professor of Pediatrics at The Ohio State University (OSU) College of Medicine, and Hideki Ueno, MD, PhD, an investigator at the Baylor Institute for Immunology Research at Baylor University, demonstrated how certain T cells in the blood are stimulated to provide protective antibody responses with seasonal flu vaccines.
The overall prevalence of protective antibody against measles virus in primary school children in Saddar town, Karachi was 80% while 16% (64 cases) suffered from measles despite receiving vaccine with maximum cases suffering before one year of age.