Immunoglobulins play a key role in the body’s immune system. They are proteins produced

by specific immune cells called plasma cells in response to bacteria, viruses, and other

microorganisms as well as exposures to other substances that are recognized by the body as

"non-self” harmful antigens. This test measures the amount of immunoglobulins A, G, and M

(IgA, IgG, IgM) in the blood and, in certain circumstances, in cerebrospinal fluid (CSF) or

saliva.