Antibodies to myelin-associated glycoprotein are found in cerebrospinal fluid in polyneuropathy associated with monoclonal serum IgM
M. Cruz, Y. P. Jiang, J. Ernerudh, G. Solders, T. Olsson, P. O. Osterman and H. Link
Department of Neurology, Karolinska Institute, Huddinge University Hospital, Stockholm, Sweden.
Antibodies to myelin-associated glycoprotein (MAG) have been demonstrated
in the serum samples from about half the patients with polyneuropathy
associated with serum IgM monoclonal component. We examined cerebrospinal
fluid (CSF) and serum samples from 13 patients with this disease by
enzyme-linked immunosorbent assay for anti-MAG IgM antibodies. We detected
these antibodies in both CSF and serum samples in 10 of the patients; in
three of them the antibodies were at higher levels in the CSF. The
remaining three patients had anti-MAG IgM antibodies in the CSF only.
Intrathecal production of anti-MAG IgM antibodies is thus common in
polyneuropathy associated with IgM monoclonal component. In three patients,
examined on two occasions from 1 to 7 years, high anti-MAG IgM antibody
levels persisted in CSF and serum samples. Among 165 patients with other
neurologic diseases, including 60 with multiple sclerosis and 60 control
subjects with tension headache, anti-MAG IgM antibodies were detected in
the CSF from three patients (two with multiple sclerosis, one with aseptic
meningitis), and in the serum sample of one patient with multiple
sclerosis. Whether the frequent occurrence of anti-MAG IgM antibodies in
CSF and their intrathecal synthesis has pathogenetic relevance for the
development of polyneuropathy associated with IgM monoclonal component is
unsure.