SUBCLASS TYPING OF IGG PARAPROTEINS BY IMMUNOFIXATION ELECTROPHORESIS

We present a simple method for subclass typing of IgG paraproteins, wi th which we have demonstrated a large number of paraproteins that were undetected by conventional immunofixation techniques. The types and d istribution of IgG subclass paraproteins were analyzed in 92 human ser a in which IgG paraproteins had been demonstrated. The IgG subclass pa raproteins were separated by agarose gel electrophoresis rapidly and s imply and then typed with the use of sheep anti-human monospecific IgG 1-IgG4 antibodies. In 24 of the sera analyzed, IgG subclass typing rev ealed 25 additional monoclonal bands that were not detected by convent ional immunofixation electrophoresis with anti-IgG antisera. Most of t hese belonged to a different subclass type. The overall subclass frequ encies were 68% IgG1, 13% IgG2, 16% IgG3, and 3% IgG4. The distributio n of paraprotein subclasses, however, was different in monoclonal gamm opathies of undetermined significance in which more IgG3 was shown, wh ereas in non-Hodgkin lymphomas the number of IgG2 paraproteins was gre ater than expected; this finding may have diagnostic and prognostic si gnificance.