No cytomegalovirus DNA in sera from patients with anti-MAG/SGPG antibody-associated neuropathy.

with Anti-MAG/SGPG Antibody–Associated Neuropathy Sachiko Irie, MD, PhD,* Naomi Kanazawa, BS,† Mieko Ogino, MD, PhD,* Toyokazu Saito, MD, PhD,* and Tadao Funato, PhD‡ In a recent study by Yuki and colleagues, cytomegalovirus (CMV) DNA was detected in sera from 23 of 26 patients (88%) with IgM anti-myelin–associated glycoprotein (antiMAG)/sulfated glucuronyl paragloboside (SGPG) antibody– associated neuropathy. Anti-MAG/SGPG antibody–associated neuropathy is a slowly progressive neuropathy and generally occurs in elderly patients with IgM M proteinemia. It has been experimentally confirmed that immunization with MAG and transfer of anti-MAG/SGPG antibodies cause demyelinating neuropathy. Yuki and colleagues suggested that CMV infections induce IgM anti-MAG/SGPG antibodies based on the results of their study. We also examined serum CMV DNA by means of the polymerase chain reaction (PCR) assay in 13 patients with IgM M proteinemia and anti-MAG/SGPG antibody–associated neuropathy. Serum IgM anti-MAG antibodies were detected by immunoblotting, and serum IgM anti-SGPG antibodies were detected by thin-layer chromatography immunostaining. For the PCR, primers were synthesized from genomic CMV DNA sequences based on the major immediate early gene of the Towne strain, which were confirmed not to cross-react with other herpes viruses. The PCR was also performed in all of these patients using primers derived from the early gene corresponding to the DNA polymerase of CMV. In the PCR for both genes, serum CMV DNA was negative in all patients, in 1 of whom it was examined at another point during the course of the study. CMV DNA was also negative in blood cells from 3 patients. CMV usually causes latent infections throughout life. Ninety-five percent of the Japanese population has latent CMV infections. In compromised hosts, including fetuses, transplant patients, and acquired immunodeficiency syndrome patients, CMV causes pantropic organic disturbances. A CMV infection is confirmed by the detection of CMV DNA in samples of organs or tissues obtained by biopsy. CMV DNA detection in serum or blood cells should indicate the activation or reactivation of CMV. Therefore, primary infections or reinfections could occur in patients with CMV DNAemia. Yuki and co-workers did not mention whether their patients showed symptoms caused by direct CMV infections or whether they had high titers of serum IgG anti-CMV antibodies representing continuous CMV infections. In conclusion, we could not find any correlation between anti-MAG/SGPG antibody–associated neuropathy and serum CMV DNA. Further investigations are necessary to clarify whether patients with anti-MAG/SGPG antibody–associated neuropathy have CMV DNAemia or not.