A type of protein found in blood and tissue fluids, also known as an antibody. Such proteins are produced by B-lymphocytes (a type of white blood cell), and their function is to bind to substances in the body that are recognized as foreign antigens. This binding is crucial for the destruction of antigenbearing microorganisms. Immunoglobulins also play a key role in allergies and hypersensitivity reactions.
Immunoglobulin G (IgG) is the major class of immunoglobulin of the 5 in the blood (IgA, IgD, IgE, IgG, and IgM). Its molecule consists of 2 parts: 1 binds to an antigen; the other binds to other cells, which then engulf the microorganisms bearing the antigen.
Immunoglobulins can be extracted from the blood of people who have recovered from certain infectious diseases and used for passive immunization.
(Ig) n. one of a group of structurally related proteins (*gammaglobulins) that act as antibodies. Several classes of Ig with different functions are distinguished – IgA, IgD, IgE, IgG, and IgM. They can be separated by *immunoelectrophoresis. See antibody.
Body proteins that act as antibodies. 1. IgG: The immunoglobulin that can be measured in the serum approximately two weeks after a challenge by an antigen. Can cross the placenta from mother to foetus. 2. IgM: The immunoglobulin that can be measured very soon after a challenge by an antigen. The level returns to a non-measurable level very quickly and so this measurement is useful as a test for recent envenomation (or illness). Cannot cross the placenta from mother to foetus. Presence in a neonate therefore indicates infection of the body. 3. IgE: Reaginic antibody; immunoglobulin found in association with allergic or homocytotrophic responses. 4. IgA: Secretory antibody; immunoglobulin found in nonvascular fluids, such as the saliva, bile, aqueous humor, synovial fluide etc.... immunoglobulins
(anti-D Ig) a preparation of anti-D, a *rhesus factor antibody formed by Rh-negative individuals following exposure to Rh-positive blood (usually by exchange between fetal and maternal blood in Rh-negative women who carry a Rh-positive fetus). Anti-D Ig is administered (by intramuscular injection) to Rh-negative women within 72 hours of giving birth to a Rh-positive child (or following miscarriage or abortion) to prevent the risk of *haemolytic disease of the newborn in a subsequent child. It rapidly destroys any remaining Rh-positive cells, which could otherwise stimulate antibody production affecting the next pregnancy. Anti-D is also available as antenatal prophylaxis to all Rh-negative pregnant women.... anti-d immunoglobulin
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