Data from: Diagnostic and prognostic value of the cerebrospinal fluid concentration of immunoglobulin free light chains in clinically isolated syndrome with conversion to multiple sclerosis

Background and objective: In this study, we evaluated the diagnostic and
prognostic significance of cerebrospinal fluid free light chains (CSF FLC)
at the time of clinically isolated syndrome (CIS). Methods: We compared
FLC-parameters at the moment of CIS in patients with conversion to
multiple sclerosis (MS) after 2 years (CIS-MS), patients who remained
stable both clinically and radiologically after 2 years (CIS-nonMS),
patients with non-inflammatory neurologic diseases (NIND) as a comparison
group and patients with other inflammatory neurologic diseases (IND) with
intrathecal oligoclonal bands (OCB) synthesis. ROC-analysis was conducted
to define FLC-assay characteristics and cut-off values. We also compared
FLC-concentrations in CIS patients to determine their OCB-status. A
correlation analysis was performed between FLC-concentrations and the
expanded disability scale score (EDSS), annualized relapse rate (ARR) and
MRI-activity (i.e., number of new and gadolinium-enhancing (Gd+) lesions)
in patients. Results: The levels of kappa-FLC (k-FLCCSF) and lambda-FLC
(λ-FLCCSF) as well as kappa- and lambda-quotients (Q-k and Q-λ) were
elevated in CIS-MS compared to the CIS-nonMS and NIND groups. These levels
did not differ significantly when compared with the IND group. We
identified several patients with high k-FLCCSF and λ-FLCCSF in
OCB-negative CIS and IND groups. The level of k-FLCCSF production was
significantly higher in OCB-positive patients in the CIS-MS group compared
to the CIS-nonMS group. The concentrations of k-FLCCSF and Q-k in the
CIS-MS group showed significant correlation with the level of EDSS after 2
years (k-FLC: r = 0.4477,p = 0.0016; Q-k: r = 0.4621, p = 0.0016).
λ-FLCCSF and Q-λ inversely correlated with the number of Gd+ lesions (CSF
λ-FLC: r = -0.3698, p = 0.0223; Q-λ: r = -0.4527, p = 0.0056). Conclusion:
The concentration of CSF FLC predicts conversion to MS within 2 years
following CIS. OCB-positive patients with an early conversion have a
higher concentration of CSF-FLC. We have also shown a prognostic
significance of k-FLCCSF for future EDSS-progression.