Measles virus polypeptide-specific antibody profile in multiple sclerosis.

Elevated antibody (Ab) titers to measles virus (MV) is a frequent finding in MS. Although MV-Abs are synthesized intrathecally, it is not known whether this is due to polyclonal activation of B cells recruited from the blood, recognition of MV antigens within the CNS, or cross-reactivity with myelin antigens. This study examined these possibilities using purified MV polypeptides. We examined Ab reactivity to each polypeptide in serum and CSF from 21 MS patients, 5 with subacute sclerosing panencephalitis (SSPE), and 11 patients with other neurologic diseases (OND), and serum from 5 patients with acute MV infection and 11 normal controls. The serum of all subjects tested contained reactivity with MV and the 5 polypeptides. Of 21 MS patients, 20 had CSF reactivity with MV compared with 3/11 ONDs and 5/5 SSPE patients. Intrathecal MV-Ab synthesis was present in 11/21 MS patients, 5/5 SSPE, and in none of the ONDs. Nine of 21 MS patients had intrathecal synthesis of Ab to 2 MV polypeptides. Serum and CSF reactivity in MS patients was skewed towards the F polypeptide. The results are consistent with the concept of polyclonal B cell activation within the CNS, but the heightened response to F could also reflect cross-reactivity with a relevant antigen in MS.