Immunoelectrophoresis (IEP)
Immunoelectrophoresis (IEP) is a semiquantitative laboratory technique used to measure the levels of three primary immunoglobulins in the blood: immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin A (IgA). This method is often employed when increased immunoglobulin levels are detected in serum protein electrophoresis tests. While IEP can be conducted on various specimens, including urine and cerebrospinal fluid, it typically involves serum collected through routine venipuncture. The procedure involves placing the specimen in a well on a semi-solid gel, applying an electric current to separate the proteins by charge, and using an antiserum to identify and measure the specific immunoglobulins.
Although IEP has valuable diagnostic applications, it is frequently supplanted by quantitative immunofixation tests in clinical settings. Elevated or decreased immunoglobulin levels indicated by IEP can suggest a range of conditions, from cancers like multiple myeloma and chronic lymphocytic leukemia to various chronic infections and autoimmune diseases. It is critical to interpret IEP results in conjunction with a patient’s medical history and clinical judgment, as elevated immunoglobulins may also arise from recent vaccinations or specific medications. Overall, IEP serves as an important tool in the diagnostic process, providing insights into immune function and potential underlying health issues.
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Subject Terms
Immunoelectrophoresis (IEP)
ALSO KNOWN AS: Gamma globulin electrophoresis, immunoglobulin electrophoresis, amyloidosis - electrophoresis serum
DEFINITION: Immunoelectrophoresis (IEP) is a semiquantitative method used in clinical and research laboratories to determine the levels of three major immunoglobulins in the blood—immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin (IgA). The quantitative immunofixation (IFE) test often replaces IEP in clinical laboratories for diagnostic purposes.
Cancers diagnosed:Multiple myeloma, chronic lymphocytic leukemia, Waldenström macroglobulinemia, lymphoma
Why performed: An IEP test is often performed when the immunoglobulins are increased in a serum protein electrophoresis test.
Patient preparation: The IEP test may be performed on urine, cerebrospinal fluid (CSF), or the serum obtained from a blood specimen collected by routine venipuncture.
Steps of the procedure: The specimen is placed in a well on a slide prepared with a semi-solid gel. An electric current is passed through the gel, causing the different serum proteins to separate according to their varying electric charges. An antiserum is placed in a trough alongside the separated immunoglobulins. The antibodies in the antiserum attach to the specific immunoglobulins. This reaction is measured, and relative quantities of IgM, IgG, and IgA per deciliter of patient serum are reported to the ordering physician.
After the procedure: The physician may order an immunofixation test to further quantify the IgM, IgG, and IgA.
Risks: This procedure has no risks other than those associated with specimen collection. Because the IEP test results may be applied to many conditions, follow-up tests are necessary for a differential diagnosis.
Results: While some cancer diagnoses are associated with elevated immunoglobulins, increased immunoglobulins can also suggest recent vaccinations or treatment with hydralazine, isoniazid, phenytoin (Dilantin), procainamide, oral contraceptives, methadone, steroids, therapeutic gamma globulin, or tetanus toxoid and antitoxin. Consequently, immunoelectrophoresis test results must be interpreted in the context of the patient’s history and clinician judgment.
IEP test results demonstrating elevated or decreased IgM, IgG, or IgA levels may indicate various conditions.
Increased IgM may point to Waldenström macroglobulinemia, an increased secretion of IgM caused by lymphocytes, chronic infections such as hepatitis, mononucleosis, and autoimmune diseases such as rheumatoid arthritis. Decreased IgM may suggest acquired immunodeficiency syndrome (HIV/AIDS), immunosuppression caused by steroids, or leukemia.
Increased IgG may indicate chronic liver disease, autoimmune diseases, hyperimmunization reactions, or chronic infections like tuberculosis or sarcoidosis. Decreased IgG can indicate Wiskott-Aldrich syndrome, HIV/AIDS, or leukemia.
Increased IgA can point to chronic liver disease, infections, or inflammatory bowel disease. Decreased IgA is seen in ataxia-telangiectasia, low blood protein (hypoproteinemia), and drug-induced immunosuppression.
Bibliography
Cawley, Leo P. Electrophoresis and Immunoelectrophoresis. Little, 1969.
Doan, Thao, et al. Immunology. 3rd ed. Wolters, 2022.
“Immunoelectrophoresis—Blood.” University of California, 2022, www.ucsfhealth.org/medical-tests/immunoelectrophoresis---blood. Accessed 20 June 2024.
“Immunoelectrophoresis—Urine.” MedlinePlus, 29 Apr. 2022, medlineplus.gov/ency/article/003592.htm. Accessed 20 June 2024.
Male, David K., and Ivan M. Roitt, editors. Immunology. 9th ed. Mosby/Elsevier, 2021.