Multiple sclerosis: use of light-chain typing to assist diagnosis.

Although the presence of oligoclonal IgG with abnormal kappa/lambda light-chain ratio in multiple sclerosis (MS) has been known for many years, this finding has not been put to diagnostic use in most routine clinical laboratories. In a retrospective study we report differences in the oligoclonal banding patterns between multiple sclerosis and non-MS patients. We had sufficient cerebrospinal fluid (CSF) on 36 from 71 patients with oligoclonal bands for immunofixation for kappa and lambda light chains, and for free kappa and free lambda. Thirteen out of 14 patients with clinically confirmed MS had predominantly IgG (kappa) banding. In contrast, in seven out of eight patients with diagnoses other than MS the IgG was linked to both kappa and lambda light chains in approximately equal proportions. Nine out of 14 patients with probable/possible/suspected MS showed predominantly IgG (kappa) banding; five others in this group had both IgG (kappa) and IgG (lambda) and free lambda light chains. The finding of IgG (kappa) bands in CSF samples with oligoclonal bands supports a diagnosis of MS.