plasma immunoglobulin measurement blood immunoglobulin A level plasma immunoglobulin A level 2014-01-27T12:21:17Z CMO:0002096 JSmith The amount in a specified sample of plasma of one or more types of immunoglobulin A (IgA), one of the most prevalent of the five classes of antibodies produced by the body. IgA is found in all secretions of the body and is the major antibody in the tears, saliva, and mucous membranes lining the intestines and bronchi, constituting an important factor in mucosal immunity. clinical_measurement_ontology plasma IgA level