- any of several classes of structurally related proteins that function as antibodies or receptors and are found in plasma and other body fluids and in the membrane of certain cells.Compare IgA, IgD, IgE, IgG, IgM.
- the fraction of the blood serum containing antibodies.
- an antibody. Abbreviation: Ig
- any of five classes of proteins, all of which show antibody activity. The most abundant ones are immunoglobulin G (IgG) and immunoglobulin A (IgA)
- Any of a group of large glycoproteins secreted by plasma cells in vertebrates that function as antibodies in the immune response by binding the specific antigens.
- See antibody.