IDENTIFICATION OF BENCE-JONES PROTEINS BY ELECTROPHORESIS

Plasma cell dyscrasia is a disease caused by a monoclonal population of plasma cells. Usually, workup for this disease is prompted by the appearance of a paraprotein in serum, but a significant number of cases exhibit only a Bence Jones protein in urine. Immunofixation electrophoresis (IFE) is the most sensitive method presently used for identifying Bence Jones proteinuria. Many laboratories screen samples for IFE by urine protein electrophoresis (UPE) because it is less laborious than IFE. This review describes the techniques of UPE and IFE, and compares IFE with UPE and the older immunoelectrophoresis. IFE patterns that are difficult to interpret are discussed, including problems of antigen or antibody excess, migration of free light chains as multiple bands, multiple banding ladder patterns, interference by nonspecific binding of anti-human animal antibodies, nonspecific background staining, and coincidental migration of bands. Examples of problems are shown. Solutions, such as avoiding excessive concentration, using highly purified antisera, and using separate antisera from different sources for confirming suspect samples are discussed.