Comparison of capillary zone and immunosubtraction with agarose gel and immunofixation electrophoresis for detecting and identifying monoclonal gammopathies

Capillary zone electrophoresis (CZE) and immunosubtraction electrophoresis (ISE) were evaluated for ability to detect and immunotype monoclonal protei ns, compared with agarose gel electrophoresis (AGE) and immunofixation elec trophoresis (IFE), respectively Six hundred seventeen serum samples Were an alyzed with CZE and AGE to determine sensitivity and specificity in detecti ng IFE-confirmed monoclonal gammopathies. Both techniques detected all mono clonal spikes due to IgM (n = 8), IgG (n = 38), and free light chains (n = 3). Agarose gel electrophoresis, however, detected only 11 of 14 (79%) IgA monoclonal spikes detected with CZE. In a second study, 78 serum samples, 4 8 of which had a monoclonal gammopathy confirmed with IFE, were evaluated w ith ISE. Only 60% to 75% of the monoclonal gammopathies were correctly immu notyped with ISE by 4 readers blinded to the IFE immunotype. Thus CZE was m ore sensitive than AGE in detecting low concentrations of monoclonal protei ns, bur ISE is less accurate than IFE in determining the immunotype of the monoclonal gammopathy.