Journal Article

Assessment of Intrathecal Free Light Chain Synthesis: Comparison of Different Quantitative Methods with the Detection of Oligoclonal Free Light Chains by Isoelectric Focusing and Affinity-Mediated Immunoblotting

Byrtusová, Monika, Kušnierová, Pavlína, Kurková, Barbora, Švagera, Zdeněk, Zapletalová, Olga, Bartoš, Vladimír, Zeman, David, Všianský, František, Hradílek, Pavel

2016

Overview

We aimed to compare various methods for free light chain (fLC) quantitation in cerebrospinal fluid (CSF) and serum and to determine whether quantitative CSF measurements could reliably predict intrathecal fLC synthesis. In addition, we wished to determine the relationship between free kappa and free lambda light chain concentrations in CSF and serum in various disease groups. We analysed 166 paired CSF and serum samples by at least one of the following methods: turbidimetry (Freelite™, SPAPLUS), nephelometry (N Latex FLC™, BN ProSpec), and two different (commercially available and in-house developed) sandwich ELISAs. The results were compared with oligoclonal fLC detected by affinity-mediated immunoblotting after isoelectric focusing. Although the correlations between quantitative methods were good, both proportional and systematic differences were discerned. However, no major differences were observed in the prediction of positive oligoclonal fLC test. Surprisingly, CSF free kappa/free lambda light chain ratios were lower than those in serum in about 75% of samples with negative oligoclonal fLC test. In about a half of patients with multiple sclerosis and clinically isolated syndrome, profoundly increased free kappa/free lambda light chain ratios were found in the CSF. Our results show that using appropriate method-specific cut-offs, different methods of CSF fLC quantitation can be used for the prediction of intrathecal fLC synthesis. The reason for unexpectedly low free kappa/free lambda light chain ratios in normal CSFs remains to be elucidated. Whereas CSF free kappa light chain concentration is increased in most patients with multiple sclerosis and clinically isolated syndrome, CSF free lambda light chain values show large interindividual variability in these patients and should be investigated further for possible immunopathological and prognostic significance.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Affinity / Autoimmune diseases / Biology and Life Sciences / Case-Control Studies / Cerebrospinal fluid / Chains / Demyelinating Diseases - blood / Demyelinating Diseases - cerebrospinal fluid / Demyelinating Diseases - diagnosis / Enzyme-Linked Immunosorbent Assay - instrumentation / Enzyme-Linked Immunosorbent Assay - methods / Fluids / Focusing / Humans / Immunoblotting / Immunoblotting - instrumentation / Immunoblotting - methods / Immunoglobulin kappa-Chains - biosynthesis / Immunoglobulin kappa-Chains - blood / Immunoglobulin kappa-Chains - cerebrospinal fluid / Immunoglobulin lambda-Chains - biosynthesis / Immunoglobulin lambda-Chains - blood / Immunoglobulin lambda-Chains - cerebrospinal fluid / Immunoglobulins / Isoelectric focusing / Isoelectric Focusing - instrumentation / Isoelectric Focusing - methods / Laboratories / Latex / Light / Light chains / Medical diagnosis / Medicine and Health Sciences / Methods / Multiple sclerosis / Multiple Sclerosis - blood / Multiple Sclerosis - cerebrospinal fluid / Multiple Sclerosis - diagnosis / Nephelometry / Nephelometry and Turbidimetry - instrumentation / Nephelometry and Turbidimetry - methods / Neurology / Observer Variation / Patients / Quantitation / Reproducibility of Results / Research and Analysis Methods / ROC Curve / Studies / Synthesis / Turbidimetry / Urine