Test Background Immunoglobulins are produced by plasma cells constitutively and upon presentation of an immunogenic stimulus. There are five isotype classes: IgM, IgA, IgG, IgD and IgE. IgD is expressed on the surfaces of mature B cells to initiate B cell activation; IgM circulates as a pentameric complex typically involved in mediating immune responses to initial infection, whereas IgG (the predominant Ig class) has the most wide-ranging of effector responses. IgA predominates through the GI tract and mucosal surfaces, while IgE is associated with hypersensitivity disorders and mediating responses to parasitic infection. Elevations of immunoglobulins may correspond to infection (typically polyclonal) or to plasma cell dyscrasia (monoclonal, occasionally bi- or tri-clonal).
Clinical Indications Assessment of immunoglobulin-associated immunodeficiency Confirmation of diagnosis of myelomatosis Monitoring of established myeloma/B-cell dyscrasia/lymphoma