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- Title
Monoclonal gammopathy missed by capillary zone electrophoresis.
- Authors
Schild, Christof; Egger, Florence; Kaelin-Lang, Alain; Nuoffer, Jean-Marc
- Abstract
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 36 g/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.
- Subjects
MONOCLONAL gammopathies; CAPILLARY electrophoresis; MONOCLONAL antibodies; BLOOD protein electrophoresis; UREA
- Publication
Clinical Chemistry & Laboratory Medicine, 2011, Vol 49, Issue 7, p1217
- ISSN
1434-6621
- Publication type
Article
- DOI
10.1515/CCLM.2011.189