Detection of Polyclonal Increases in Immunoglobulin G4 Subclass by Distinct Patterns on Capillary Serum Protein Electrophoresis

Abstract

Increased polyclonal IgG4 has a characteristic SPEP pattern that may mimic monoclonal gammopathy, even on immunosubtraction. κ Pseudo-restriction might reflect the naturally high κ/λ ratio of the IgG4 subclass. Autoantibodies were common, and the greatest IgG4 increases had clinical features of IgG4-RD.