Study of gammopathies with immunofixation electrophoresis.

Immunofixation electrophoresis and immunoelectrophoresis were compared in 60 samples (51 sera and 9 urines) containing apparently homogenous bands, detected by electrophoresis. To determine the correlation with clinical findings, the patients were divided into three groups: (1) symptomatic with monoclonal immunoelectrophoretic patterns; (2) asymptomatic with monoclonal immunoelectrophoretic patterns; (3) asymptomatic with polyclonal immunoelectrophoretic patterns. The results from immunoelectrophoresis and immunofixation electrophoresis were consistent with each other in all cases of Groups I and III in terms of clonality (i.e., whether monoclonal or polyclonal) and immunoglobulin class; whereas in Group II, which was composed of asymptomatic patients, two sera and three urines were identified to have monoclonal changes by immunoelectrophoresis but polyclonal changes by immunofixation electrophoresis. It is recommended that immunoelectrophoresis still be used for routine clinical service, but supplemented by immunofixation electrophoresis in equivocal cases, namely: (1) light-chain changes masked by an umbrella effect of immunoglobulin G (IgG); (2) abnormal bands located in atypical areas or overlapped with a normal serum protein; (3) a normal-looking "free" light chain present in the urine, mimicking Bence Jones protein; (4) controversial cases of biclonal gammopathy; (5) mini-monoclonal or oligoclonal protein bands; (6) immune complexes.