Oligoclonal IgG and free chains in multiple sclerosis demonstrated by thin-layer polyacrylamide gel isoelectric focusing and immunofixation.

A modified technique of isoelectric focusing on thin-layer polyacrylamide gel followed by immunofixation with monospecific antisera was used to identify individual cerebrospinal fluid (CSF) and serum proteins and to define the oligoclonal reaction observed in multiple sclerosis (MS). "Normal" IgG gave about 20 to 30 bands at pH 3.5 to 9.5, IgA about 10 bands at pH 3.5 to 6.4, beta-trace protein a smear at pH 3.5 to 8.5, and gamma-trace protein 1 or 2 bands at pH 8.0, 9.5 or both. Up to 11 oligoclonal IgG bands migrating between pH 6.5 and 9.5 were found in CSF from 26 of 27 consecutive patients with MS and also in 20 of the corresponding sera, although at lower numbers and concentrations. In 26 patients, 1 or more of the bands corresponding to normal polyclonal IgG were stronger in CSF than in serum. These data support the hypothesis that two colonies of lymphocytes are activated intrathecally, one of them synthesizing oligoclonal and the other polyclonal IgG. Up to 11 mostly faint bands of free light chains, predominantly of lambda type and migrating between pH 3.5 and 9.5, were found in 8 of 9 CSF specimens from patients with MS.