Analysis of cerebrospinal fluid and serum of patients with multiple sclerosis by means of anti-idiotypic antisera

Twelve antisera were prepared, each specific for idiotype(s) of IgG from the cerebrospinal fluid (CSF) of an individual patient with multiple sclerosis (MS). Idiotype-positive (ld(+)) IgG represented 24 to 33% of the CSF-IgG. Radioautographic analysis showed that ld(+)IgG in CSF and in serum had a restricted electrophoretic mobility. From serum of three patients, at least two different noncross-reacting Id(+)IgG fractions were isolated. The anti-Id antisera, which detect IgG considered to be of importance in MS, were used to measure Id(+)IgG in CSF and in serum. Relative to the total IgG, Id(+)IgG was always enriched in CSF, which suggests intrathecal synthesis of such IgG. However, in all patients the absolute concentration of Id(+)IgG was higher in serum than in CSF. Studies attempting to demonstrate cross-reactivity between the IgG of different patients were negative.