IgG synthesis within the brain in multiple sclerosis and subacute sclerosing panencephalitis.

Intracerebral IgG synthesis was measured in patients with multiple sclerosis (MS), subacute sclerosing panencephalitis (SSPE) and in two control groups--patients with other neurological disorders and patients with non-neurological diseases. Significantly increased synthesis was found at all times in SSPE (P less than 0.001). Significantly elevated values were also found in MS (P less than 0.001), but in this group increased values were found mainly during relapse. These findings emphasize the immunological component in SSPE where there is known to be persistent measles virus infection in the brain, and in MS where the aetiology is unknown. Intracerebral IgG synthesis appears to be of diagnostic value in MS. The cerebrospinal fluid (CSF) IgG/total protein ratio was also measured in MS, and correlated only moderately well with the calculated IgG synthesis, indicating that the ratio provides a cruder estimate of intracerebral IgG synthesis.