HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) CME: Take the course for this article: Volume 73, Number 9, September 1, 2009 Data Supplement Correspondence: Submit a response Alert me when this article is cited Alert me when Correspondence are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Kuijf, M. L. Articles by Jacobs, B. C. PubMed PubMed Citation Articles by Kuijf, M. L. Articles by Jacobs, B. C. Related Collections All Immunology All Clinical Neurology Hematologic Peripheral neuropathy EMG

Detection of anti-MAG antibodies in polyneuropathy associated with IgM monoclonal gammopathy

From the Departments of Neurology (M.L.K., A.P.T.-G., P.A.v.D., B.C.J.) and Immunology (M.L.K., A.P.T.-G., H.H., B.C.J.), Erasmus MC, Rotterdam; Department of Neurology (M.E.), Spaarne Ziekenhuis, Hoofddorp; and Department of Neurology (M.E., L.H.v.d.B., J.S., N.C.N.), the Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, The Netherlands.

Address correspondence and reprint requests to Dr. Mark L. Kuijf, Erasmus MC, s'-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands m.kuijf{at}erasmusmc.nl

Background: Detection of serum antibodies to myelin-associated glycoprotein (MAG) by Western blot (WB) is a valuable assay to diagnose a distinct type of demyelinating polyneuropathy with immunoglobulin M (IgM) monoclonal gammopathy. In this study, the diagnostic accuracy of a new and more practical ELISA to detect these antibodies was validated.

Methods: Routine WBs from 2 independent laboratories and ELISA were used to detect anti-MAG IgM in serum from 207 patients with neuropathy and controls. The sensitivity and specificity of these assays were compared and related to the patient clinical and electrophysiologic characteristics.

Results: In ELISA, anti-MAG antibodies were found in serum from 49 (72%) of 68 patients with demyelinating polyneuropathy and IgM monoclonal gammopathy. However, in this subgroup of patients, only 30 (44%) and 37 (54%) were positive in the 2 WBs. All of the patients positive in the 2 WBs were also positive in ELISA. A high correlation was found for IgM activity in ELISA to MAG and sulfate-3-glucuronyl paragloboside (SGPG) (Spearman = 0.72, p < 0.0001), supporting the notion that the shared sulfated glucuronic acid moiety of MAG and SGPG is preserved. Most patients positive in anti-MAG ELISA had a slowly progressive sensory–motor demyelinating polyneuropathy, even if the WB was negative. In control groups, however, 4 WB-negative patients with a nondemyelinating monoclonal gammopathy–related polyneuropathy were positive in anti-MAG ELISA. The remaining samples were negative in ELISA.

Conclusion: ELISA is more sensitive than Western blot to diagnose anti–myelin-associated glycoprotein related polyneuropathy, although a positive serology may be found in other forms of polyneuropathy as well.

Abbreviations: BTU = Bühlmann titer unit; IgM = immunoglobulin M; MAG = myelin-associated glycoprotein; ROC = receiver operating characteristic; SDS-PAGE = sodium dodecyl sulfate polyacrylamide gel electrophoresis; SGPG = sulfate-3-glucuronyl paragloboside; UMCU = University Medical Center of Utrecht; WB = Western blot.

Supplemental data at www.neurology.org

The ELISA plates to perform the anti-MAG and anti-SGPG serology in this study were provided by Bühlmann Laboratories AG, Switzerland. This company did not otherwise sponsor this study and had no influence on the design, testing, analysis, conclusions, and writing of the study. This research was funded by a grant from the Erasmus MC.

Disclosure: Author disclosures are provided at the end of the article.

Received January 14, 2009. Accepted in final form June 10, 2009.