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Monoclonal gammopathy missed by capillary zone electrophoresis

Schild, Christof ; Egger, Florence ; Kaelin-Lang, Alain ; Nuoffer, Jean-Marc

In: Clinical Chemistry and Laboratory Medicine, 2011, vol. 49, no. 7, p. 1217-1219

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    Titel
    • Monoclonal gammopathy missed by capillary zone electrophoresis
    Autor
    • Schild, Christof. Institute of Clinical Chemistry, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
    • Egger, Florence. Institute of Clinical Chemistry, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
    • Kaelin-Lang, Alain. Department of Neurology, Inselspital, Bern University Hospital, Bern, Switzerland
    • Nuoffer, Jean-Marc. Institute of Clinical Chemistry, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Clinical Chemistry and Laboratory Medicine, 2011, vol. 49, no. 7, p. 1217-1219. Walter de Gruyter
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:294828
    Summary
    Background: Serum protein electrophoresis is used as a screening test for monoclonal gammopathies. Here, we present a case of a high-concentration monoclonal immunoglobulin (M-protein) that was missed by serum protein electrophoresis on a Capillarys 2 capillary zone electrophoresis system. The aim of our study was to identify the reason for the failure of the system to detect the M-protein. Methods: M-protein solubility was examined in response to temperature, pH, ionic strength, the chaotropic agent urea and the reducing agent 2-mercaptoethanol. Results: Precipitation of the M-protein was not cold-induced, but solubility decreased at pH 8.5 or higher, when the pH approached the apparent isoelectric point. The M-protein also precipitated in alkaline Capillarys 2 electrophoresis buffer (pH 10), which was the reason for the false-negative electrophoresis result. Precipitation of the M-protein was not related to the ionic strength of the buffer. Solubility improved in presence of urea. Pre-treatment of serum with 2-mercaptoethanol revealed the missing M-protein peak of 36g/L on the electropherogram. Conclusions: This case shows that insolubility of M-proteins in alkaline buffer is one possible cause of false-negative results on capillary zone electrophoresis systems. False-negative results should be considered, especially when accompanying laboratory results are inconsistent with the electropherogram