Analysis of Concentrations of Monomethyl Fumarate in Patients with Multiple Sclerosis: Result from Routine Health Care.

BACKGROUND: Dimethyl fumarate is used to treat patients with relapsing-remitting multiple sclerosis. After ingestion, it is rapidly hydrolyzed to the active primary metabolite monomethyl fumarate. OBJECTIVE: The main objective of our study was to analyze serum concentrations of monomethyl fumarate during routine health care in patients with multiple sclerosis treated with a fixed dose of dimethyl fumarate. METHODS: In the pilot cross-sectional study, data from 42 patients treated with dimethyl fumarate at a dose of 240 mg twice daily were collected. Concentrations of the active metabolite monomethyl fumarate were determined at 1-8 h (median, 3 h) or 10-14 h (median, 13 h) after taking the dose. The relationship between monomethyl fumarate concentrations and absolute lymphocyte count was evaluated. RESULTS: Concentrations of monomethyl fumarate ranged from 2.5-3177.9 µg/L, with most concentrations being undetectable approximately 10 hours after administration. In the 1-8 h (median, 3 h) post-dose subgroup, the concentration/dose ratio ranged widely from 0.04-6.62. The median concentration of monomethyl fumarate in the group with the absolute lymphocyte count <0.8 x 10^9/l was more than four times higher than in the group with the absolute lymphocyte count ≥0.8 x 10^9/l (median 440.1 µg/L versus 98.4 µg/L). CONCLUSION: The wide interindividual variability in monomethyl fumarate pharmacokinetics could contribute to the differential response to dimethyl fumarate in multiple sclerosis patients. A nonsignificant but noticeable trend was observed in the relationship of higher serum monomethyl fumarate concentrations to absolute lymphocyte counts.

Serum teriflunomide concentrations in routine multiple sclerosis therapy: A cross-sectional pilot study.

BACKGROUND: Teriflunomide is administered orally to treat relapsing-remitting multiple sclerosis. In this prospective pilot study, the free and total serum concentrations of teriflunomide obtained during routine health care were measured and their relationship with disease activity was evaluated. METHODS: Eighty-nine patients were included in this study. Blood samples were collected from April 2021 to February 2022, and free and total teriflunomide serum concentrations were measured. Patient assessment involved monitoring of blood counts and potential adverse effects of teriflunomide. RESULTS: In the steady-state group, total teriflunomide concentrations ranged from 14.7 to 144.2 mg/L, while free concentrations from 31.1 to 389.7 µg/L. In the non-steady-state group, the total concentration ranged from 2.2 to 59.3 mg/L, with free concentrations ranging from 6.8 to 143.5 µg/L. In the steady-state group, a significant inverse correlation was found between absolute peripheral blood lymphocyte count and both total and free teriflunomide serum concentrations. CONCLUSION: Although all patients were treated with the same dose, up to a 10-fold difference in total and free teriflunomide serum concentrations, and up to a 5-fold difference in steady-state trough concentrations were observed. This vast interindividual variability can potentially lead to toxicity or, conversely, to suboptimal therapeutic concentrations of teriflunomide, with the risk of further worsening of multiple sclerosis compensation.

Immunoablative therapy followed by autologous hematopoietic stem cell transplantation as the first-line disease-modifying therapy in patients with multiple sclerosis.

INTRODUCTION: Immunoablative therapy followed by autologous hematopoietic stem cell transplantation (AHSCT) is one of the possible disease-modifying therapies (DMTs) for patients with multiple sclerosis (MS). In this case series, we would like to present six patients with MS, who underwent AHSCT as the first-line DMT. CASE REPORTS: Six MS patients with a rapid progression of disability with or without relapses underwent AHSCT as the first-line DMT at the University Hospital Ostrava between 2018 and 2021. The conditioning regimens for AHSCT used were a medium-intensity regime BEAM (Carmustine, Etoposid, Cytarabin, Melphalan) and low-intensity regime based on Cyclophosphamide. Four out of six patients showed some disability progression after AHSCT, so the rapid progression of MS was just slowed down by AHSCT. One patient developed activity on magnetic resonance imaging three months after AHSCT, and two experienced mild relapses during the follow-up period. None of our patients developed grade 4 non-hematological toxicity; all infections were mild. In one patient, an allergic reaction probably to dimethyl sulfoxide was observed. CONCLUSION: Our case series of 6 patients shows that AHSCT is a promising therapeutic approach to slow down the rapid progression of clinical disability in MS patients with a good safety profile.

Does initial high efficacy therapy in multiple sclerosis surpass escalation treatment strategy? A comparison of patients with relapsing-remitting multiple sclerosis in the Czech and Swedish national multiple sclerosis registries.

BACKGROUND: In relapsing-remitting multiple sclerosis (RRMS) the most common treatment strategy has been to start with low-moderate efficacy disease modifying therapy (LE-DMT) and to escalate to more efficacious treatments in cases of breakthrough disease activity. However, recent evidence suggests a better outcome in patients commencing with moderate-high efficacy DMT (HE-DMT) immediately after clinical onset. OBJECTIVE: The aim of this study is to compare disease activity and disability outcomes in patients treated with the two alternative strategies using the Swedish and Czech national multiple sclerosis registries, taking advantage of the fact that the relative frequency of each strategy differs markedly between these two countries. METHODS: Adult RRMS patients who initiated their first-ever DMT between 2013 and 2016 and were included in the Swedish MS register were compared with a similar cohort from the MS register of the Czech Republic using propensity score overlap weighting as a balancing method. The main outcomes of interest were time to confirmed disability worsening (CDW), time to achieve an expanded disability status scale (EDSS) value of 4, time to relapse, and time to confirmed disability improvement (CDI). To support the results, a sensitivity analysis focusing solely on patients from Sweden starting with HE-DMT and patients from the Czech Republic starting with LE-DMT was performed. RESULTS: In the Swedish cohort, 42% of patients received HE-DMT as initial therapy compared to 3.8% of patients in the Czech cohort. The time to CDW was not significantly different between the Swedish and Czech cohorts (p-value 0.2764), with hazard ratio (HR) of 0.89 and a 95% confidence interval (CI) of 0.77-1.03. Patients from the Swedish cohort exhibited better outcomes for all remaining variables. The risk of reaching EDSS 4 was reduced by 26% (HR 0.74, 95%CI 0.6-0.91, p-value 0.0327), the risk of relapse was reduced by 66% (HR 0.34, 95%CI 0.3-0.39, p-value <0.001), and the probability of CDI was three times higher (HR 3.04, 95%CI 2.37-3.9, p-value <0.001). CONCLUSION: The analysis of the Czech and the Swedish RRMS cohorts confirmed a better prognosis for patients in Sweden, where a significant proportion of patients received HE-DMT as initial treatment.

Liquid chromatography - tandem mass spectrometry method for determination of natalizumab in serum and cerebrospinal fluid of patients with multiple sclerosis.

Natalizumab is a humanized recombinant monoclonal IgG4 antibody used in the treatment of multiple sclerosis. Commonly used methods for natalizumab and anti-natalizumab antibodies quantification are enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay, respectively. Measurement of therapeutic monoclonal antibodies can be challenging due to the resemblance to human plasma immunoglobulins. Recent developments in mass spectrometry enables to analyze vast variety of large protein molecules. The aim of this study was to develop a LC-MS/MS method for determining natalizumab in human serum and cerebrospinal fluid (CSF) and apply it to clinical settings. For successful quantification, it was necessary to find specific sequences of peptides in natalizumab. This immunoglobulin was treated with dithiothreitol and iodoacetamide, cleaved with trypsin into short specific peptides and determined on a UPLC-MS/MS system. An Acquity UPLC BEH C18 column at 55 °C and gradient elution was used for analysis. Intra- and interassay accuracies and precisions were tested at four concentration levels. Precision was determined by coefficients of variation and was in the range of 0.8-10.2 %, with accuracy in the range of 89.8-106.4 %. The concentration of natalizumab in patient samples ranged from 1.8 to 193.3 µg/mL. The method was validated according to the European Medicines Agency (EMA) guideline, met all acceptance criteria for accuracy and precision, and is suitable for clinical applications. In comparison to immunoassay, which can be elevated by cross-reaction with endogenous immunoglobulins, the results of developed LC-MS/MS method are more accurate and specific.

Is breastfeeding in MS harmful or not? An answer from real-world Czech data.

INTRODUCTION: The influence of breastfeeding and it´s duration on the course of multiple sclerosis (MS) is unclear. Here we analyzed a real-world data for breastfeeding women with MS and their disease course collected from a Czech national registry ReMuS. OBJECTIVES: To identify risk factors associated with not initiating breastfeeding after delivery, to analyze the impact of breastfeeding on the MS disease course, evaluate the assumption, that breastfeeding is not harmful in MS patients, and compare the disease course by breastfeeding status. MATERIALS AND METHODS: Using propensity score matching we compared Expanded Disability Status Scale (EDSS), confirmed disease worsening (CDW) and annual relapse rate (ARR) in breastfeeding and non-breastfeeding MS patients according to disease duration, disease modifying treatment (DMT) before pregnancy, last EDSS score before conception, age, and ARR during pregnancy. We also compared these parameters between breastfeeding patients not using a DMT and non-breastfeeding patients who resumed DMT within 3 months after delivery. EDSS, ARR, and CDW were collected at 12, 24, and 36 months after delivery. RESULTS: A total of 1681 pregnancies that ended in delivery were analyzed from 2013 through 2020. Change in ARR and EDSS values and 6-months CDW did not significantly differ between the analyzed groups. Compared with non-breastfeeding women who resumed DMT early after delivery, breastfeeding women with MS did not experience worse clinical outcomes even without initiating a DMT. DISCUSSION: Breastfeeding in Czech women with MS did not negatively affect the disease course and can be supported. Patients with MS can be treated with certain DMTs alongside breastfeeding and there is no need to stop breastfeeding, if the patient is clinically stable.

The Czech National MS Registry (ReMuS): Data trends in multiple sclerosis patients whose first disease-modifying therapies were initiated from 2013 to 2021.

AIMS: Multiple sclerosis treatment strategies are changing in the Czech Republic. According to data from 2013-2021, the proportion of patients starting high-efficacy disease-modifying therapies is increasing. In this survey, we describe the actual data trends in multiple sclerosis (MS) patients beginning their first disease­modifying therapies (DMTs) from 2013 to 2021. The secondary objective was to present the history, data collection, and scientific potential of the Czech National MS registry (ReMuS). METHODS: First, using descriptive statistics, we analysed the data for patients starting their first DMTs, either platform (including dimethyl fumarate) or high-efficacy DMTs (HE-DMTs), for each successive year. Second, a detailed description of the history, data collection, completeness, quality optimising procedures, and legal policies of ReMuS is provided. RESULTS: Based on the dataset from December 31, 2021, the total number of monitored patients with MS in ReMuS increased from 9,019 in 2013 (referred from 7 of 15 MS centres) to 12,940 in 2016 (referred from all 15 Czech MS centres) to 17,478 in 2021. In these years, the percentage of patients treated with DMTs in the registry ranged from 76 to 83%, but the proportion of patients treated with HE-DMTs changed from 16.2% in 2013 to 37.1% in 2021. During the follow-up period, a total of 8,491 treatment-naive patients received DMTs. The proportion of patients (all MS phenotypes) starting HE-DMTs increased from 2.1% in 2013 to 18.5% in 2021. CONCLUSION: Patient registries, including ReMuS, provide an essential quality data source, especially in light of the increasing percentage of patients on HE-DMTs. Although early initiation of HE-DMT can provide considerable benefits, it also carries greater potential risks. Consistent long-term follow-up of patients in real­world clinical practice, which only registries allow, is therefore crucial to evaluate the efficacy and safety of therapeutic strategies, for epidemiological research and to assist decision making by healthcare providers and regulatory bodies.

Cerebrospinal fluid neurofilament light chains and CXCL13 as predictive factors for clinical course of multiple sclerosis.

AIM: The aim of this study was to identify whether NfL and CXCL13 cerebrospinal fluid (CSF) concentrations at diagnostic lumbar puncture can predict the course of multiple sclerosis (MS) in terms of relapses, higher expanded disability status scale (EDSS) and magnetic resonance imaging (MRI) activity. METHODS: We conducted a single-centre prospective observational cohort study at the MS center, University Hospital Ostrava, Czech Republic. CSF NfL (cNfL) and CXCL13 concentrations were examined (ELISA method) in patients with clinically isolated syndrome (CIS) and relapsing-remitting MS (RRMS) at the time of diagnostic lumbar puncture. RESULTS: A total of 44 patients with CIS or early RRMS were enrolled, 31 (70.5%) of whom were women. The median age at the time of CSF sampling was 31.21 years (IQR 25.43-39.32), and the follow-up period was 54.6 months (IQR 44.03-59.48). In the simple and multiple logistic regression models, CXCL13 levels did not predict relapses, MRI activity or EDSS > 2.5. Similarly, cNfL concentrations did not predict relapses or MRI activity in either model. In the multiple regression, higher cNfL levels were associated with reaching EDSS > 2.5 (odds ratio [OR] 1.002, 95% confidence interval [CI] 1.000 to 1.003). CONCLUSIONS: Our data did not confirm cNfL and/or CXCL13 CSF levels were predictive factors for disease activity such as relapses and MRI activity at the time of diagnostic lumbar puncture in patients with RRMS. While cNfL CSF levels predicted higher disability only after adjustment for other known risk factors, elevated CSF CXCL13 did not predict higher disability at all.

Analysis of cerebrospinal fluid cells by flow cytometry: Comparison to conventional cytology.

AIMS: This study compared the results obtained by basic immunophenotyping of cerebrospinal fluid (CSF) cells by flow cytometry (FC) to the results of conventional cytology and evaluated the possibility of detailed analyses of CSF B-cell subpopulations. METHODS: Samples from 42 patients were examined by conventional cytology (native and/or pre-centrifuged CSF) and FC. The results from 15 patients without evidence of organic neurological disease were used to estimate reference ranges. RESULTS: Pre-centrifugated CSF had significantly higher cell yield on the cytologic slide, but cell subpopulation percentages were altered; the percentage of lymphocytes was significantly higher and monocytes significantly lower compared to both native CSF slides and FC. The percentage of granulocytes was higher in FC compared to cytology. For leukocyte count, the following reference ranges were estimated for Fuchs-Rosenthal chamber (FR) counting and FC, respectively: leukocytes ≤4.7/µL and ≤2.5/µL, lymphocytes ≤4.1/µL and ≤1.8/µL, monocytes ≤1.2/µL and ≤0.9/µL, and granulocytes 0/µL and ≤0.2/µL. The following reference ranges were estimated for basic subpopulations: T-lymphocytes 84.1-100%, B lymphocytes 0.0-1.5%, NK cells 0.0-6.3%, NKT cells 0-9.5%, and CD3+CD4+/CD3+CD8+ 0.8-4.9. Using a volume of 1.2-2.4 mL, the number of B lymphocytes was too low (<20) in samples with ≤2.7 cells/µL in the FR. CONCLUSIONS: Even normal CSF samples are amenable to basic mononuclear cell subpopulation analysis by FC. However, analysis of the B-cell subpopulations requires either a larger sample volume or selection of samples with ≥ 3 cells/µL.

Analysis of the Group of Pediatric Patients With Relapsing-Remitting Multiple Sclerosis: Data From the Czech National Registry.

Importance: Multiple sclerosis can also affect children. Approximately 3-10% of patients develop multiple sclerosis before the age of 16. Objective: The aim of this analysis is to describe the characteristics of pediatric patients with multiple sclerosis who started their treatment with disease-modifying drugs in 2013-2020, with data obtained from the Czech National Registry of patients with multiple sclerosis. Design and Setting: A method of retrospective analysis conducted with 134 pediatric patients with multiple sclerosis was used. Results: The findings reveal that the mean age at the date of the introduction of the first disease-modifying drugs treatment is 15.89 years, and gender does not play any role. In addition, moderate (51.6%) and mild (45.2%) relapses are predominant in these young patients. Seventy five percent of patients will not experience a confirmed progression of the expanded disability status scale within 54.7 months from starting the treatment. Furthermore, the results confirm that the first-choice treatment is interferon beta-a and glatiramer acetate, which is common for adult patients. However, some factors, such as a low efficacy or a lack of tolerance may impact on treatment discontinuation in children. Conclusion: More research should be performed on novel disease-modifying drugs for this target group.

Is pregnancy in MS patients safe and what is its impact on MS course? Real World evidence of 1533 pregnancies in Czech Republic.

BACKGROUND: A special care of MS women planning a pregnancy is highly demanding especially in the terms of disease modifying treatment (DMD) decisions and counselling regarding periods of conception, pregnancy and postpartum period. OBJECTIVE: To provide data about impact of pregnancy, delivery or miscarriage/artificial abortion on MS disease course in Czech women with MS based on analysis of retrospective data from the Czech national registry ReMuS. METHODS: The analysis focused on women with MS with at least one record of pregnancy in the registry. Clinical data (EDSS, relapses) were collected prior to conception, during pregnancy and after delivery or miscarriage/artificial abortion. These data were analysed according to baseline characteristics of DMD treatment prior to conception and according to breastfeeding status. RESULTS: A total of 1 533 pregnancies were analysed from the period of 2013 until 31st December 2019. The occurrence of relapses and worse EDSS was significantly related to the treatment with escalation therapy prior to conception. Relapses were significantly more frequent in women who breastfed less than 3 months than in women who breastfed more than 3 months or did not breastfeed at all. Patients treated with either fingolimod or natalizumab prior to pregnancy were significantly more likely to develop relapses during pregnancy. CONCLUSION: Pregnancy and postpartum period were generally safe for Czech women with MS. Better disease outcomes were observed in those who had been treated with first line injectable DMDs prior to conception and those who either breastfed more than 3 months or did not breastfeed at all. We confirmed the assumption of rebound phenomenon of MS after discontinuation of treatment due to planned pregnancy both for fingolimod and natalizumab.

Determination of chitinase 3-like 1 in cerebrospinal fluid in multiple sclerosis and other neurological diseases.

OBJECTIVES: Chitinase 3-like 1 (CHI3L1) is an extracellular monomeric single-chain glycoprotein expressed by many types of cells. Its elevated levels were found in cerebrospinal fluid in central nervous system (CNS) inflammatory diseases patients. The aim of the study was 1) to validate the reference interval of cerebrospinal fluid (CSF) CHI3L1 in a control group; 2) to measure the CHI3L1 concentration in different diagnosis groups .including multiple sclerosis (MS); and 3) to correlate those values with other biomarkers of axonal damage or neuroinflammation in different grous. METHODS: The study included 132 CSF samples sent to the Department of Clinical Biochemistry, Institute of Laboratory Diagnostics, University Hospital Ostrava. Concentrations of CHI3L1, CXCL13 chemokine, neurofilament light chains, and phosphorylated neurofilament heavy chains were determined by enzyme-linked immunosorbent assays. IgG oligoclonal bands were detected by isoelectric focusing in agarose gels followed by immunofixation. IgM and FLC oligoclonal bands were analyzed by IEF followed by affinity immunoblotting. The group consisted of 42 patients with multiple sclerosis, 14 with clinically isolated syndrome, 11 with other central nervous system inflammatory diseases, 46 with non-inflammatory diseases of the central nervous system, 4 with inflammatory diseases of the peripheral nervous system, and 15 controls. RESULTS: The estimated reference values of CHI3L1 were 28.6-182.5 µg.L-1. Statistically significant differences of CSF CHI3L1 concentrations were found among diagnosis groups (p < 0.0001), after age adjustment (p = 0.002). There was a statistically significant relationship between CHI3L1 and NFL in the MS group (rs = 0.460; P = 0.002), and between CHI3L1 and pNFH in the MS group (rs = 0.691; P < 0.001). No statistically significant difference was found in the categorical comparison of CHI3L1 in the MS group and other diagnostic groups as well as when using the Mann-Whitney U test for CHI3L1 with additional parameters with and without oligoclonal bands present. CONCLUSIONS: CSF CHI3L1 values differ depending on diagnosis and correlate significantly with concentrations of the axonal damage markers CSF neurofilament light chains, and CSF phosphorylated neurofilament heavy chains, but not with CSF concentrations of the inflammatory marker CXCL13. Thus, CSF CHI3L1 could be another promising prognostic, albeit probably etiologically nonspecific, biomarker of MS.

Cerebrospinal fluid oligoclonal IgM test in routine practice: Comparison with quantitative assessment of intrathecal IgM synthesis.

BACKGROUND: Intrathecal IgM synthesis demonstrated either as cerebrospinal fluid (CSF)-restricted oligoclonal (o-) IgM bands or calculated using various formulas has been linked to more aggressive multiple sclerosis (MS) course. However, the proportion of MS patients showing intrathecal IgM synthesis varies largely between studies. We aimed to explore the relation between different formulas and results of o-IgM, and to assess the frequency of o-IgM bands in an unselected series of samples. METHODS: 432 samples were analyzed for o-IgM, o-IgG and quantitative measures of IgM and IgG synthesis. IgM index and formulas of Reiber, Auer and Öhman were compared to the result of the o-IgM test. RESULTS: At the cut-off commonly used, the non-linear formulas for intrathecal synthesis were specific (>94%) but rather insensitive (<40% even at a cut-off of 4 CSF-restricted bands) compared to o-IgM. No significant difference was noted in the performance of different formulas. At a cut-off of 4 bands, 61% of MS patients, but none of the controls were positive for o-IgM. CONCLUSIONS: Formulas for intrathecal IgM synthesis are insensitive compared to o-IgM. We propose to evaluate samples with 2 or 3 extra-CSF IgM bands as borderline and only samples with 4 or more as definitely positive.

Comparison of Therapies in MS Patients After the First Demyelinating Event in Real Clinical Practice in the Czech Republic: Data From the National Registry ReMuS.

Background: Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system. Well-established drugs used for MS patients after the first demyelinating event in the Czech Republic include glatiramer acetate (GA), interferon beta-1a (IFNß-1a), IFN beta-1b (IFNß-1b), peginterferon beta-1a (peg-IFNß-1a), and teriflunomide. Objective: The objective of this observational study was to compare the effectiveness of the abovementioned drugs in patients with MS who initiated their therapy after the first demyelinating event. Patients were followed for up to 2 years in real clinical practice in the Czech Republic. Methods: A total of 1,654 MS patients treated after the first demyelinating event and followed up for 2 years were enrolled. Evaluation parameters (endpoints) included the annualized relapse rate (ARR), time to next relapse, change in the Expanded Disability Status Scale (EDSS) score, and time of confirmed disease progression (CDP). When patients ended the therapy before the observational period, the reason for ending the therapy among different treatments was compared. Results: No significant difference was found among the groups of patients treated with IFNß-1a/1b, GA, or teriflunomide for the following parameters: time to the first relapse, change in the EDSS score, and the proportion of patients with CDP. Compared to IFNß-1a (44 mcg), a significant increase in the percentage of relapse-free patients was found for GA, but this treatment effect was not confirmed by the validation analysis. Compared to the other drugs, there was a significant difference in the reasons for terminating GA therapy. Conclusion: Small differences were found among GA, IFNß and teriflunomide therapies, with no significant impact on the final outcome after 2 years. Therefore, in clinical practice, we recommend choosing the drug based on individual potential risk from long-term therapy and on patient preferences and clinical characteristics.

Neurofilament levels in patients with neurological diseases: A comparison of neurofilament light and heavy chain levels.

BACKGROUND: Neurofilaments are the major cytoskeletal components of neurons, and cell injury leads to their release into the surrounding area. The aim of this study was to compare the cerebrospinal fluid (CSF) and serum (S) concentrations of neurofilament light chains (NFLs) and phosphorylated neurofilament heavy chains (pNFHs). METHODS: Neurofilament concentrations were measured in CSF and S samples from 172 patients using three enzyme-linked immunosorbent assays. Excel, Stata version 13, MedCal version 17.9.7., and NCSS 2007 software were used for the statistical analysis. RESULTS: There was a statistically significant correlation between the concentrations of CSF NFL and CSF pNFH (rs  = 0.748; n = 89; P < 0.001), but Passing-Bablok regression showed systematic deviation between the values obtained using the two assays. This indicates that the assays were not interchangeable. CSF pNFH and S pNFH concentrations showed low correlation. The kappa statistic showed moderate conformity between CSF pNFH and CSF NFL concentrations (κ = 0.556). CONCLUSIONS: The CSF NFL and CSF pNFH assays gave clinically consistent results that reflected the degree of axonal damage, independent of any particular neurological diagnosis. The S pNFH assays had a lower predictive value due to the low correlation coefficient and the kappa index of the CSF pNFH method.

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.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Quantitation of free light chains in the cerebrospinal fluid reliably predicts their intrathecal synthesis.

BACKGROUND: The results of free light chains quantitation in the cerebrospinal fluid were recently compared with the presence of cerebrospinal fluid-restricted oligoclonal IgG, but not oligoclonal free kappa light chains and oligoclonal free lambda light chains. We therefore aimed to compare the performance of the quantitative tests with the qualitative one for the same molecule. METHODS: Seventy-five paired cerebrospinal fluid and serum samples were analysed for oligoclonal IgG, oligoclonal free kappa light chains and oligoclonal free lambda light chains. Cerebrospinal fluid and serum free kappa and lambda light chains were quantified using Freelite™ kits on SPA Plus analyzer. ROC curves were analysed for the prediction of intrathecal synthesis and compared for cerebrospinal fluid concentration, cerebrospinal fluid/serum quotient (QfLC) and index (QfLC/QAlbumin). The presence of cerebrospinal fluid-restricted oligoclonal free kappa light chains and oligoclonal free lambda light chains bands was used as reference. RESULTS: No statistically significant differences were observed among cerebrospinal fluid concentration, QfLC and index for the prediction of free light chain intrathecal synthesis. Each parameter was able to predict the occurrence of cerebrospinal fluid-restricted oligoclonal free light chain bands (AUCs 0.932-0.999). However, we noted elevated cerebrospinal fluid free light chain concentrations in the absence of cerebrospinal fluid-restricted oligoclonal free light chain bands in two patients with very high serum free light chain values. CONCLUSIONS: Quantitation of cerebrospinal fluid free light chains reliably predicts their intrathecal synthesis. Yet, cerebrospinal fluid/serum quotient may still be preferred to correct for high serum free light chain concentrations. An appropriate formula should be sought to correct for blood-cerebrospinal fluid barrier status.

Oligoclonal free light chains in cerebrospinal fluid as markers of intrathecal inflammation. Comparison with oligoclonal IgG.

AIMS: To compare the sensitivity and specificity of CSF-restricted oligoclonal IgG and free light chains as markers of multiple sclerosis and other inflammatory neurological diseases. METHODS: 196 paired CSF and serum samples were examined for oligoclonal IgG and oligoclonal free light chains. The sensitivity and specificity of the tests were calculated and optimal cut-offs for the number of CSF-restricted oligoclonal bands were then determined by analysis of receiver operating characteristic curves. RESULTS: Optimal cut-off values were ≥5 IgG bands for multiple sclerosis, ≥4 IgG bands for inflammatory neurological disease, ≥6 free κ, and ≥2 free λ bands for both purposes. Using these cut-off values, sensitivities and specificities for multiple sclerosis were 83.8% and 91.3% for IgG, 83.8% and 81.0% for free κ, and 67.6% and 75.4% for free λ. For inflammatory neurological disease, sensitivities and specificities were 60.8% and 95.7% for IgG, 69.6% and 92.6% for free κ, and 64.8% and 86.2% for free λ. CONCLUSIONS: Although exact cut-off values may vary according to method, reporting borderline results as positive, may compromise the specificity of the test and should be avoided.. The detection of intrathecal free light chain synthesis may be of value especially when the oligoclonal IgG test is negative or borderline, even though its specificity is slightly lower.