Ig
Meaning of Ig: Ig is the abbreviation used in laboratory and immunology reports for immunoglobulin, the family of antibody proteins made by immune cells.
Definition of Ig
Ig is a common abbreviation for immunoglobulin, a family of glycoproteins produced by B lymphocytes and plasma cells that function as antibodies. Each immunoglobulin molecule is built from two identical heavy chains and two identical light chains joined together, forming a structure with one region that binds a specific antigen and another that interacts with the rest of the immune system.
Several classes of immunoglobulin exist, commonly labeled IgG, IgM, IgA, IgD, and IgE, and each plays a somewhat different role. IgM tends to appear early in a new immune response, IgG circulates widely and reflects longer term recognition of a previously encountered antigen, IgA concentrates in mucous membranes and secretions such as saliva and tears, and IgE participates in allergic reactions.
Blood tests that measure specific immunoglobulin classes are used to evaluate how well the immune system is functioning, to look for evidence of past or current infection, and to investigate certain allergic and autoimmune conditions.
Also known as
Used in a sentence
The laboratory panel included measurement of several immunoglobulin classes to evaluate the patient's humoral immune function.
Good to know
Total immunoglobulin levels and levels of individual classes such as IgG or IgA are interpreted differently, since a normal total can mask an abnormality confined to a single class.