Clonally expanded plasma cells in the cerebrospinal fluid of patients with central nervous system autoimmune demyelination produce "oligoclonal bands".

Clonally expanded plasma cells (cePC) and oligoclonal IgG (oligoclonal bands, OCB) in the cerebrospinal fluid (CSF) suggest an involvement of B cell mechanisms in autoimmune CNS demyelination. Due to their CSF-restricted occurrence, OCB are commonly believed to be the products of B cells inside the borders of the blood brain barrier. A comparison of CSF cell Ig transcriptomes and CSF-Ig proteomes recently demonstrated, that in multiple sclerosis patients CSF cells are the origin of CSF immunoglobulins. We expand these findings by applying anti-idiotypic antibodies to detect specific heavy chain CDR3 idiotopes of cePC-produced antibodies amongst OCB in the CSF of a patient each with MS and acute disseminated encephalomyelitis.