[Immunoenzymatic determination of free immunoglobulin light chains in the cerebrospinal fluid: its value in the biological diagnosis of multiple sclerosis].

Based on previous data on free immunoglobulin light chains in the cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS), we evaluated free kappa and lambda light chains in the CSF from 3 patients groups: (a) 42 with MS, (b) 16 with other neurological inflammatory diseases (ONID) and (c) 42 with non inflammatory neurological diseases (NIND) used as control. The kappa and lambda light chains contents were evaluated using a specific and sensitive (0.5 mcg/ml) enzyme linked immunosorbent assay (ELISA). Whole CSF immunoglobulins G (CSF-IgG) concentrations were determined by an immuno-nephelometric method and CSF oligoclonal banding was assessed by agarose gel electrophoresis. Elevated free kappa light chains levels were found in 36 of the 42 (85.7%) MS-CSF, and only in 2 of the 16 (12.5%) ONID-CSF. Moreover, all MS-CSF with oligoclonal banding (21/42) exhibited detectable free kappa light chains. In contrast, elevated free lambda light chains or whole CSF-IgG concentrations were found not so specific. These results suggest that free kappa light chains measurement in MS-CSF may have an important diagnostic usefulness. This assay offers a reliable alternative to other available procedures and may constitute complementary technique in routine investigation of MS-CSF.