Journal ofNeurology, Neurosurgery, and Psychiatry 1989;52:949-953 Immunoglobulin M in the cerebrospinal fluid: an indicator of recent immunological stimulation

SUMMARY Using a sensitive new method for detecting oligoclonal immunoglobulin M (IgM) in unconcentrated cerebrospinal fluid (CSF), the intrathecal synthesis of IgM was correlated with that of free light chains in patients with multiple sclerosis, infections of the central nervous system and other neurological conditions. A strong correlation was found between the presence of oligoclonal IgM and that of free light chains in the CSF from patients with multiple sclerosis and infections of the central nervous system. No oligoclonal IgM response was observed in patients with non-inflam-matory or non-infectious neurological conditions. This implies that oligoclonal IgM has the same diagnostic significance as free light chains. Electrophoretically restricted immunoglobulins (Ig) commonly occur in the cerebrospinal fluid (CSF) of patients with inflammatory and infectious diseases of the central nervous system (CNS) in the form of oligoclonal bands where each band represents the product of a single B-lymphocyte clone. Another immunological parameter is CSF free ligh