Relatively restricted migration of polyclonal IgG4 may mimic a monoclonal gammopathy in IgG4-related disease.

Am J Clin Pathol 2014 Jul;142(1):76-81

Department of Pathology, University of Michigan Hospital and Health Systems, Ann Arbor.

Objectives: IgG4-related disease (IgG4-RD) is an increasingly recognized syndrome of unknown etiology that can affect a wide variety of organs. The commonly shared features include tumor-like swelling of the involved organs, a lymphoplasmacytic infiltrate enriched with polyclonal IgG4-positive plasma cells, variable degree of fibrosis, and elevated serum concentrations of polyclonal IgG4.

Methods: In a qualitative retrospective study, the electrophoretic characteristics of serum from patients with increased polyclonal IgG4 were studied to see if a reproducible pattern could be identified.

Results: We demonstrate that a characteristic focal band bridging the β and γ fraction by serum protein electrophoresis may be a first serologic indication for IgG4-RD. We further demonstrate that significant κ:λ skewing can occur in the polyclonal IgG4 fraction.

Conclusions: The focal band detected by electrophoresis in sera from patients with IgG4-RD can be confirmed as polyclonal by immunofixation or immunosubtraction. Because these bands may be predominately of one light chain isotype, they could be misinterpreted as monoclonal gammopathies.

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http://dx.doi.org/10.1309/AJCP41XCVBHEQCELDOI Listing
July 2014
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