Virus-specific immunoglobulins in multiple sclerosis.
When the specificity and titre of IgG and IgM towards six viruses was compared by immunofluorescence in sera and CSF of patients with multiple sclerosis (MS) and control subjects, the MS specimens differed from controls in three properties. 
 
1. A proportion, probably 22/56, of MS sera contained IgM that was weakly specific for measles virus-infected cells only. The antigen remains unidentified. 
 
2. The titre of IgG specific for measles virus and that against herpes simplex virus is slightly increased in the serum of MS patients but the titre of IgG specific for mumps, rubella and varicella zoster is not significantly altered. The altered titre against vaccinia is of doubtful significance. 
 
3. A proportion, 16/25, of CSF from MS patients contain measles virus-specific IgG and of these eight contained herpes virus-specific IgG. One contained herpes virus-specific IgG alone. Rubella virus IgG, of comparable titre in serum to measles- and herpes-specific IgG, was not found in the CSF.