ABSTRACT
Whereas serum protein electrophoresis can detect restrictions that resemble monoclonal gammopathies, it cannot definitively identify a restriction as an M-protein. For that, immunochemical methods together with electrophoresis must be employed. In this chapter, I review the principles of the techniques employed for the identification of restrictions seen on protein electrophoresis as Mproteins. Most laboratories now perform immunofixation electrophoresis (IFE) to identify the restriction as an M-protein. Laboratories using capillary zone electrophoresis (CZE) may be able to perform immunosubtraction (ISUB), depending on which CZE system they are using. Immunoelectrophoresis (IEP) is still used by some laboratories. It does have a couple of advantages over immunofixation, but it is slow, less sensitive and more difficult to interpret than IFE. Lastly, cases of heavy chain disease benefit from performance of immunoselection (ISEL).
