Simplify your Neurology Diagnostic Testing with the Freelite Mx™ Kappa Assay
Evaluate intrathecal immunoglobulin synthesis with the Freelite Mx Kappa Assay
Intrathecal immunoglobulin synthesis has been observed in various neurological disorders, such as Multiple Sclerosis1.
The traditional approach for the evaluation of intrathecal immunoglobulin synthesis is detection of CSF-restricted oligoclonal IgG bands (OCB)2.
OCB is a specialised gel-based technique that requires highly skilled operators to interpret.
Even when experienced professionals interpret the results, inter-laboratory and inter-observer variability can be observed3.
“[…] one of the clear advantages of кFLC is the reliable and rater-independent determination, which should overcome technical difficulties and finally allow a widespread use.”
Hegen, Multiple Sclerosis 20224
The Freelite Mx Kappa assay on the Optilite® automated analyzer measures Kappa Free Light Chain (FLC) concentration in CSF and serum. These values, alongside CSF and serum albumin measurements, are used to calculate the Kappa FLC Index.
The Kappa FLC Index is considered interchangeable with OCB testing in the 2024 McDonald criteria for the diagnosis of Multiple Sclerosis5.
The laboratory process for evaluating intrathecal immunoglobulin synthesis can be simplified with the Kappa FLC Index Freelite Mx assays run on the Optilite analyser.
A study by Sanz Diaz6 et al. evaluated the reagent cost and time required to perform the Kappa FLC Index for 252 paired Serum and CSF samples versus the traditional OCB analysis. Using the Kappa FLC Index resulted in substantial time savings and a significant cost reduction.
Cost and time analysis of 252 paired serum and CSF samples
Adapted from Sanz Diaz Front Neurol 2021.
Transform your diagnostic testing with the Optilite Analyser
Simplify your MS diagnostic testing with the Freelite Mx Kappa assay on the Optilite analyser
Use the Freelite Mx Kappa assay to calculate the Kappa FLC Index
Intrathecal synthesis of immunoglobulins is a hallmark of Multiple Sclerosis2. An elevated Kappa FLC concentration in CSF indicates intrathecal immunoglobulin synthesis3.
An impaired blood-CSF barrier can also cause Kappa FLC to appear in CSF, so the origin of CSF Kappa FLCs needs to be identified4.
Calculations that involve CSF/serum Kappa FLC and CSF/serum albumin quotients, such as Kappa FLC Index, help differentiate whether the Kappa FLCs have been intrathecally synthesized or are derived from serum3.
In cases where CSF albumin is also elevated, increases in CSF Kappa FLC are unlikely to be due to intrathecal synthesis, as increased CSF albumin indicates an impaired blood-brain barrier3.
There is a good overall agreement between Kappa FLC Index results and the absolute CSF Kappa FLC level. However, Kappa FLC Index appears superior in cases of low or modest intrathecal production of Kappa Free Light Chains3.
A Kappa FLC Index result > 6.1 is considered CSF positive in the 2024 McDonald Criteria for diagnosis of Multiple Sclerosis5.
Discover the complete solution for CSF analysis on the Optilite special protein analyser
- An assay panel that can aid in the characterization of intrathecal immunoglobulin synthesis, blood brain-barrier dysfunction and in the diagnosis of infection and inflammation of the central nervous system.
Generate results to calculate CSF/Serum ratios, using assays designed to measure both CSF and serum samples using a single instrument.
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References
- Carta S, et al. Oligoclonal bands: clinical utility and interpretation cues. Crit Rev Clin Lab Sci 2022; 1-14
- Thompson AJ, et al. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. Lancet Neurol 2018; 17:162-173
- Hegen H, et al. Cerebrospinal fluid kappa free light chains for the diagnosis of multiple sclerosis: A consensus statement. Mult Scler 2022; 29:182-195
- Hegen H, et al. Cerebrospinal fluid kappa free light chains for the diagnosis of multiple sclerosis: A systematic review and meta-analysis. Mult Scler 2022; 29:169-181
- Montalban X, et al. Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria. Lancet Neurol 2025; 24:850-865
- Sanz Diaz CT, et al. Evaluation of Kappa Index as a Tool in the Diagnosis of Multiple Sclerosis: Implementation in Routine Screening Procedure. Front Neurol 2021; 12:676527