A comparison of methods of monoclonal immunoglobulin quantitation

Abstract

Quantitation of monoclonal immunoglobulins was carried out using the following methods: densitometric scanning of electrophoretograms on cellulose acetate gel, single radial immunodiffusion, nephelometry and, in monoclonal IgM, also sedimentation analysis. To compare the methods, 20 sera with monoclonal IgG, 16 sera with monoclonal IgA and 19 sera with monoclonal IgM were used. The methods correlated well in monoclonal IgM and IgG while in IgA correlation was found only between densitometry and radial immunodiffusion. Closest correlation was observed between densitometry and sedimentation analysis in quantifying monoclonal IgM (r = 0.954). Despite good correlation, the individual values of monoclonal immunoglobulins established by different methods showed marked differences. In comparison with the immunochemical methods, the quantitation of monoclonal immunoglobulins using densitometric scanning of electrophoretograms is accessible, quick and relatively more precise method.