Polymeric IgA paraprotein on agarose gel electrophoresis immunofixation identifies a unique subset of IgA myeloma patients

Abstract

Objectives: On agarose gel electrophoresis, IgA paraprotein has a tendency to polymerise and form multiple bands on immunofixation. We decided to investigate if there are any differences in clinical parameters with monomeric vs. polymeric IgA paraprotein multiple myeloma (MM) patients.

Methods: During an 18-month retrospective and prospective cross-sectional audit review period at one Australian laboratory, we identified 92 IgA MM patients that were divided up according to monomeric or polymeric IgA paraproteins based on their appearance on IFE. Medical and pathology records were reviewed for demographic details, and laboratory data to examine for end-organ manifestations of MM.

Results: After correcting for age, polymeric IgA MM patients had a greater degree of proteinuria and hence, higher incidence of hypogammaglobulinaemia. The patients tended to have a higher quantity of paraprotein as well. No difference in mortality was seen.

Conclusions: Our study is the first to stratify IgA MM patients according to the laboratory appearance of their paraprotein and may hold important prognostic and predictive clues for these patients.

Keywords: Agarose; Electrophoresis; IgA; Monomer; Myeloma; Polymer.