antibody

(noun)

a protein produced by B-lymphocytes that binds to a specific antigen

Related Terms

  • MHC
  • opsonize

Examples of antibody in the following topics:

  • Antibody Structure

    • Variations in antibody structure allow great diversity of antigen recognition among different antibodies.
    • The constant domain, which does not bind to an antibody, is the same for all antibodies.
    • The large diversity of antibody structure translates into the large diversity of antigens that antibodies can bind and recognize.
    • Ig stands for immunoglobulin, another term for an antibody.
    • Prior to antibody secretion, plasma cells assemble IgM molecules into pentamers (five individual antibodies) linked by a joining (J) chain .
  • Antibody Functions

    • Sometimes, antibodies can be transferred from one individual to another.
    • Phagocytic enhancement by antibodies is called opsonization.
    • In fact, antibodies exhibit different affinities (attraction) depending on the molecular complementarity between antigen and antibody molecules .
    • Typically, multimeric antibodies, such as pentameric IgM, are classified as having lower affinity than monomeric antibodies, but high avidity.
    • (b) An antibody may cross-react with different epitopes.
  • Humoral Immune Response

    • An antigen is a biomolecule, such as a protein or sugar, that binds to a specific antibody.
    • An antibody/antigen interaction may stimulate an immune response.
    • Antibodies are the agents of humoral immunity.
    • Antibodies occur in the blood, in gastric and mucus secretions, and in breast milk.
    • Antibody neutralization can prevent pathogens from entering and infecting host cells.
  • The Complement System

    • The complement system is so named because it is complementary to the antibody response of the adaptive immune system.
    • Complement proteins bind to the surfaces of microorganisms and are particularly attracted to pathogens that are already bound by antibodies.
    • The classic pathway for the complement cascade involves the attachment of several initial complement proteins to an antibody-bound pathogen, followed by rapid activation and binding of many more complement proteins and the creation of destructive pores in the microbial cell envelope and cell wall.
    • The alternate pathway does not involve antibody activation.
  • Hypersensitivities

    • Upon initial exposure to a potential allergen, an allergic individual synthesizes antibodies of the IgE class; this class of antibodies also mediates the immune response to parasitic worms.
    • Antibodies that inappropriately mark self components as foreign are termed autoantibodies.
    • Antibodies and TCRs may bind self antigens that are structurally similar to pathogen antigens, which the immune receptors first raised.
    • These antibodies can damage heart muscle with autoimmune attacks, leading to rheumatic fever.
    • On first exposure to an allergen, an IgE antibody is synthesized by plasma cells in response to a harmless antigen.
  • Immunological Memory

    • During the adaptive immune response to a pathogen that has not been encountered before, known as the primary immune response, plasma cells secreting antibodies and differentiated T cells increase, then plateau over time.
    • Memory B cells that differentiate into plasma cells output ten to hundred-fold greater antibody amounts than were secreted during the primary response .
    • This rapid and dramatic antibody response may stop the infection before it can even become established.
    • In the primary response to infection, antibodies are secreted first from plasma cells.
    • Upon re-exposure to the same pathogen, memory cells differentiate into antibody-secreting plasma cells that output a greater amount of antibody for a longer period of time.
  • Plasma and Serum

    • The plasma also contains the coagulation factors and antibodies.
    • Other components in the serum include proteins, which assist with maintaining pH and osmotic balance while giving viscosity to the blood; antibodies, or specialized proteins that are important for defense against viruses and bacteria; lipids, including cholesterol, which are transported in the serum; and various other substances including nutrients, hormones, metabolic waste, and external substances, such as drugs, viruses, and bacteria.
    • Immunoglobin, a protein antibody produced in the mucosal lining, plays an important role in antibody mediated immunity.
  • Antigen-presenting Cells: B and T cells

    • An antigen is a molecule that binds to a specific antibody, often stimulating a response in the immune system as a result.
    • Their attack can kill pathogens directly or they can secrete antibodies that enhance the phagocytosis of pathogens and disrupt the infection.
    • On B cells, these receptors contain antibodies, which are responsible for antigen binding .
    • An antibody is specific for one particular antigen; typically, it will not bind to anything else.
    • B cell receptors are embedded in the membranes of B cells and bind a variety of antigens through their variable regions, or antibodies.
  • Basic Techniques in Protein Analysis

    • The western blot, or protein immunoblot, is a technique that combines protein electrophoresis and antibodies to detect proteins in a sample.
    • The protein sample is first separated by gel electrophoresis, then transferred to a nitrocellulose or other type of membrane, and finally stained with a primary antibody that specifically binds the protein of interest.
    • A fluorescent or radioactive-labeled secondary antibody binds to the primary antibody and provides a means of detection via either photography or x-ray film, respectively.
  • Cytotoxic T Lymphocytes and Mucosal Surfaces

    • Antibodies are synthesized and secreted by activated plasma cells in the spleen, which filters foreign substances and antibody-complexed pathogens from the blood.
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