DIFFERENTIAL-DIAGNOSIS OF GAMMOPATHIES BY CAPILLARY-ELECTROPHORESIS AND IMMUNOSUBTRACTION - ANALYSIS OF SERUM SAMPLES PROBLEMATIC BY AGAROSE-GEL ELECTROPHORESIS

The capabilities of capillary electrophoresis (CE) for serum protein e lectrophoresis and immunotyping have been demonstrated. CE-based syste ms specifically designed for serum protein electrophoresis and immunot yping via immunosubtraction (IS) are now available and are being evalu ated for efficiency, specificity and sensitivity by several groups. Th e use of CE for serum protein electrophoresis and immunotyping (IS) in the clinical laboratory compares well with agarose gel electrophoresi s (AGE) and immunofixation (IF) for the detection and characterization of monoclonal proteins. In addition to routine use, this technology i s useful for a subset of serum samples that are difficult to interpret with conventional technology. In this study, sera abnormalities diffi cult to detect/interpret by AGE-IF are subdivided into four categories : (i) patients with polyclonal increases in immunoglobulin, (ii) point of application artifacts, (iii) abnormalities in the beta region, and (iv) patients with free light chains. CE is superior to AGE for evalu ating samples characterized by the above abnormalities. Sera containin g monoclonal proteins within a polyclonal increase are easier to detec t by CE as well as being easier to type by IS than by IF. Point-of-app lication artifacts, periodically observed with AGE, do not exist on CE since the point of detection is remote from the point of application. Enhanced resolution in the beta region allows for increased detection of monoclonal proteins migrating in this region. Some free light chai ns are undetected by CE as a result of no apparent abnormalities on th e CE serum protein profile and, thus, still require IF for detection. CE detects more serum electrophoretic abnormalities than AGE in this c linically important group of patients with Bence Jones proteinemia.