Cerebrospinal fluid analysis and the determination of oligoclonal bands

Oligoclonal bands and kappa free light chains: Competing parameters or complementary biomarkers?

BACKGROUND

The 2024-revised McDonald criteria for multiple sclerosis (MS) proposed to incorporate cerebrospinal fluid (CSF)-specific oligoclonal bands and kappa free light chains (KFLC) as diagnostic biomarkers. While the 2017-revised criteria highlighted CSF-specific oligoclonal bands to indicate intrathecal IgG synthesis, significantly enhancing early MS diagnosis, KFLC have emerged as additional marker. Now, the question rises of whether both biomarkers serve as competing or complementary tools in MS diagnostics.

METHODS

In this narrative review, we extensively searched the literature on oligoclonal bands and KFLC determination in CSF and serum across neurological disorders, with a focus on MS, using the PubMed database to demonstrate the complementarity of both biomarkers.

RESULTS

Oligoclonal bands have long been a reliable marker of intrathecal IgG synthesis in MS, valued for their high diagnostic sensitivity, unique patient "fingerprints," clonality differentiation, semi-quantitative analysis, and pre-analytic robustness. However, they present challenges in standardization, labor-intensity, method variability, examiner dependency, and limited data on non-IgG immunoglobulins. Quantitative KFLC measurement provides rapid, examiner-independent, and cost-effective assessment across all immunoglobulin classes but might have lower specificity, lacked consensus on standardized interpretation in recent years, and is not yet supported by comprehensive prospective multinational studies on its prognostic role.

CONCLUSION

Both oligoclonal bands and KFLC have unique strengths and limitations that complement each other, potentially serving as complementary markers for evaluating intrathecal Ig synthesis in MS diagnosis. Further evidence is needed to establish the value of KFLC in MS diagnosis, thus multicenter prospective studies are being conducted to compare the diagnostic utility of both markers.

Oligoclonal IgM band patterns in multiple sclerosis: A two-center study

BACKGROUND

Cerebrospinal fluid (CSF) oligoclonal IgM bands (OCMBs) have been suggested as prognostic biomarkers in MS, but serum OCMBs meaning is still uncertain.

OBJECTIVES

We aimed to assess frequency and clinical relevance of all OCMB patterns.

METHODS

In this retrospective cohort study, 136 paired sera-CSF from consecutive persons with MS (pwMS) were tested in 2 centers for OCMBs using isoelectric focusing-immunoblotting. Active disease was defined as clinical or radiological relapse occurring during two-year follow-up. Predictors of active disease were analyzed with logistic regressions and Kaplan-Meier survival curves.

RESULTS

OCMBs were found in 6.6 % of pwMS as unique-to-CSF (pattern #2), and in 20.6 % as identical in serum-CSF (pattern #4), without between-cohort difference. Active disease was more frequent in those with pattern #2 (88.9 %) and #4 (64.3 %) than in those OCMB-negative (33.3 %, p < 0.001). In multivariate analysis, pattern #2 (OR: 15.9; 95 % CI [1.8-136]), and pattern #4 (OR: 3.3 95 % CI [1.3-8.3]) were independent predictors of active disease. In survival analysis, pattern #2 (p < 0.001) and #4 (p = 0.017) predicted radiological relapses.

CONCLUSIONS

Our data confirm that CSF OCMB marks poor prognosis in MS. However, both OCMB pattern #4 and pattern #2, with different strength prediction, might be useful to stratify pwMS deserving more aggressive treatments, although the stratification could be achieved in the near future with more standardized and easily measurable biomarkers (e.g., serum neurofilaments).

A review of laboratory practices for CSF oligoclonal banding and associated tests

Multiple sclerosis (MS) is a chronic autoimmune disorder affecting the central nervous system, often emerging in early adulthood and representing a leading cause of neurological disability in young adults. Diagnosing MS involves a combination of clinical assessment, imaging and laboratory tests, with cerebrospinal fluid (CSF)-specific immunoglobulin G (IgG) oligoclonal bands (OCB) being an important marker for fulfilling the dissemination in time criteria. A recent survey of Canadian clinical laboratories highlighted considerable variation in OCB reporting practices nationwide, spanning quality control (QC) practices, acceptable time limits between paired CSF and serum sample collections, protocols for reporting band counts, interpretation and reporting of mirrored patterns, testing panels, and interpretive thresholds. These inconsistencies impact patient care and the comparability of laboratory results across different laboratories. The Harmonized CSF Analysis for MS Investigation (hCAMI) subcommittee of the Canadian Society of Clinical Chemists Reference Interval Harmonization Working Group was established to generate recommendations for laboratory processes and reporting of CSF OCB and associated tests supporting MS diagnosis. This review serves as a foundation for these efforts, summarizing the available evidence in areas where practice variations have been noted. This review begins by examining current practices and guidelines for standardized quality assurance, including optimal QC materials, frequency, documentation, and participation in external quality assurance programs. The disparity between paired CSF and serum sample acceptability time limits was further examined by reviewing current practices and recommendations as well as compiling evidence on IgG synthesis, turnover rate, biological variation, and stability in CSF and serum samples. Additionally, this review addresses the lack of consensus on reporting the number of CSF-specific and CSF-serum matched bands, focusing on interpreter variability and clinical utility. Contributing factors and clinical implications of mirror patterns, including discussion on monoclonal gammopathies and cases of matched bands of differing staining intensity, is provided. Testing panel components including adjunctive CSF tests, such as the IgG index, to support MS investigations despite their absence from clinical guidelines is also discussed. This review also provides a comprehensive analysis of current practices, guidelines, and the evidence surrounding different cutoffs for IgG index and CSF-specific bands.

Finally, the review considers emerging biomarkers, such as the kappa free light chain index and serum neurofilament light chain, which show promise for MS diagnosis and management. This comprehensive review of current practices, guidelines, and evolving evidence will guide the hCAMI subcommittee's efforts to harmonize CSF OCB analysis and improve MS diagnosis.

Comparison of the clinical and laboratory characteristics of neuromyelitis optica spectrum disorder with or without cerebrospinal fluid oligoclonal bands: a cohort with 36-month follow-up

Purpose

This study aimed to explore the significance of cerebrospinal fluid (CSF) oligoclonal bands (OCBs) in the clinical diagnosis and evaluation of neuromyelitis optica spectrum disorder (NMOSD).

Methods

The demographic and clinical data of 143 aquaporin-4 immunoglobulin G (AQP4-IgG)-positive NMOSD patients were collected and analyzed, including the gender, age, clinical symptoms and signs, status of CSF OCBs, location and length of the affected spinal cord vertebral segments, Expanded Disability Status Scale (EDSS) at the first attack and at 36-month follow-up, relapse times within 36 months, concomitant connective tissue disease (CTD), and status of other autoimmune antibodies (oAIA).

Results

There were 15 patients (10.5%) who were positive for OCBs (OCBs+). In contrast to those with negative OCBs (OCBs-), more OCBs+ cases had concomitant CTD [5/15 (33.3%) vs. 11/128 (8.6%), p = 0.014] and oAIA [9/15 (60.0%) vs. 37/128 (28.9%), p = 0.020]. OCBs+ patients had higher CSF cell counts [15.0 (27.0)/mm3 vs. 5.0 (12.0)/mm3, p = 0.008], higher IgG index [0.68 (0.23) vs. 0.52 (0.15), p < 0.001], and more relapses within 36 months [2.0 (3.0) vs. 1.0 (2.0), p = 0.039] than OCBs- patients. More OCBs+ patients had polynuclear cell predominance in the CSF than OCBs- patients (p = 0.032). There were no significant differences between the OCBs+ and the OCBs- patients in the distribution of lesion locations; the length of the affected spinal cord vertebral segments; the concentration of CSF protein and the albumin quotient; the EDSS score at the time of lumbar puncture and at 36-month follow-up, and the onset episode, the relapse, and cumulative clinical syndrome profiles (all p > 0.05).

Conclusions

For AQP4-IgG-positive NMOSD patients, positivity for CSF OCBs is associated with higher CSF cell counts and a higher likelihood to have concomitant CTD and oAIA. OCBs+ is not uncommon in NMOSD and may predict more frequent relapses, but not a more serious illness.

Contribution of Blood Biomarkers to Multiple Sclerosis Diagnosis

BACKGROUND AND OBJECTIVES

Invasive procedures may delay the diagnostic process in multiple sclerosis (MS). We investigated the added value of serum neurofilament light chain (sNfL), glial fibrillary acidic protein (sGFAP), chitinase-3-like 1 (sCHI3L1), and the immune responses to the Epstein-Barr virus-encoded nuclear antigen 1 to current MS diagnostic criteria.

METHODS

In this multicentric study, we selected patients from 2 prospective cohorts presenting a clinically isolated syndrome (CIS). Patients were classified as (1) not presenting dissemination in space (DIS) nor dissemination in time (DIT) (noDIS and noDIT); (2) presenting DIS without DIT (DIS and noDIT); and (3) presenting both (DIS and DIT), which were used as a reference. sNfL, sGFAP, and sCHI3L1 levels were measured with single-molecule array immunoassays and EBNA1-specific IgG levels with ELISA. Biomarker levels were compared between groups using linear regression models. Receiver operating characteristic curve analyses and Youden Index were used to determine cutoff values associated with MS diagnosis during follow-up.

RESULTS

We included 181 patients (66.3% females, mean [SD] age of 35.0 [9.7] years). At baseline, 25 (13.8%) were classified as noDIS and noDIT, 62 (34.3%) as DIS and noDIT, and 94 (51.9%) as DIS and DIT. Only sNfL Z-scores discriminated between groups (DIS and DIT vs DIS and noDIT [p = 0.002], DIS and DIT vs noDIS and noDIT [p < 0.001], and DIS and noDIT vs noDIS and noDIT [p = 0.026]). In noDIS and noDIT patients (median interquartile range [IQR] follow-up of 8.1 [5.0-11.7] years), high sNfL Z-scores best predicted MS diagnosis (specificity [SP] and 95% CI of 93.3% [68.1-99.8] and positive predictive value [PPV] of 87.5% [47.3-99.7]). Among DIS and noDIT patients (median [IQR] follow-up of 6.8 [4.0-9.1] years), high sNfL Z-scores best predicted MS diagnosis (SP of 80% [28.4-99.5] and PPV of 97.3% [85.8-99.9]) without considering oligoclonal band (OB) status. In the subset of patients of this group with negative OBs, a combination of high sNfL Z-scores and sGFAP levels predicted MS diagnosis (SP of 100% [39.8-100] and PPV of 100% [54.1-100]).

DISCUSSION

These results suggest that sNfL and sGFAP may be incorporated in particular scenarios to diagnose MS in patients with CIS not fulfilling current diagnostic criteria.

Multiple sclerosis diagnosis and its differential diagnosis in patients presenting with type four 'mirror pattern' CSF oligoclonal bands

BACKGROUND

Presence of oligoclonal bands (OCBs) restricted to cerebrospinal fluid (CSF) characterizes most patients with multiple sclerosis (MS). Few data are available on the frequency of MS diagnosis and the main alternative diagnoses in patients with an initial central nervous system (CNS) demyelinating event and CSF IV pattern, the so-called 'mirror pattern'.

METHODS

Seventy-six patients presenting with OCBs pattern IV after a clinical attack suggestive of CNS demyelinating event were included in the study. Diagnostic work-up, including blood, CSF, and paraclinical examinations, and 2 years of clinical and radiological follow-up were evaluated.

RESULTS

Pattern IV occurred in 15.1% of patients. Twenty-five patients (32.8%) received a diagnosis of MS, thirty-two (42.1%) an alternative diagnosis, and nineteen (25%) remained without definite diagnosis. Most frequent alternative diagnosis was encephalopathy with atypical MRI lesions of probable vascular origin (19.7%). MS was significantly more common in patients with type IV OCB pattern (25 of 76) than in a group of patients presenting with type I OCB pattern (32 of 168, p = 0.017).

CONCLUSION

The diagnosis of MS is common in patients who present with OCBs pattern IV. However, other CNS disorders, particularly vascular encephalopathy, should be carefully considered.

Utility of Oligoclonal Band Testing in Differentiating Immune-Mediated From Infectious Central Nervous System Disorders

OBJECTIVE

This study aimed to evaluate the clinical utility of oligoclonal bands (OCB) in differentiating between immune and infectious diseases of the central nervous system (CNS).

METHODS

The study enrolled patients hospitalized with suspected autoimmune or infectious CNS disorders between 2021 and 2023. Patients were categorized into diagnostic groups: multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), autoimmune encephalitis (AE), and viral encephalitis (VE). Relevant clinical and laboratory data were collected and subjected to comparative analysis.

RESULTS

Comparative analysis among the 4 groups revealed that the immunoglobulin G (IgG) index of patients in the MS group was significantly higher than that of patients in the NMOSD and VE groups (P < 0.05). The 24-hour intrathecal synthesis rate of IgG also differed significantly between the MS and NMOSD groups, the NMOSD and AE groups, as well as the AE and VE groups (P < 0.05). The positive rate of OCB was significantly higher in the MS group than in the other 3 groups (P < 0.05). Functional abilities, measured by scores of the Modified Rankin Scale (mRS) and the Expanded Disability Status Scale (EDSS), were higher in the immune group than in the infection group at 1-week, 1-month, 6-month, and 1-year post-treatment. Among patients with immune diseases, those who were OCB-positive showed significantly smaller ΔmRS and ΔEDSS at 1-month, 6-month, and 1-year post-treatment compared with patients who were OCB-negative (P < 0.05).

CONCLUSION

The IgG index and 24-hour intrathecal synthesis rate of IgG served as valuable early indicators for distinguishing between CNS immune and infectious diseases. Positive OCB findings were more common in patients with MS and often associated with poor prognosis and increased risk of disease recurrence.

Epstein-Barr nuclear antigen 1 antibody-based indices are increased in patients with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic central nervous system (CNS) disease, which is diagnosed by a combination of clinical symptoms and magnetic resonance imaging and measurement of an increased intrathecal antibody synthesis. Genetic as well as environmental factors influence onset of the disease, where especially Epstein-Barr virus (EBV) infection is directly involved in MS development. In this open retrospective study, we aimed to elaborate whether various serum and cerebrospinal fluid (CSF)-based EBV antibody indices may aid in the diagnosis of MS.

METHODS

Epstein-Barr nuclear antigen (EBNA)1 IgG concentrations in serum and CSF of relapsing-remitting (RR)MS patients (n=61) (M:F 28:33, average 40 years), optic neuritis patients (n=26) (M:F 9:17, average 47 years) and healthy controls (HCs) (n=15) (M:F 8:7, average 43 years) were determined by enzyme-linked immunosorbent assay. The obtained EBNA1 IgG levels were compared to factors such as total IgG, albumin concentrations, specific antibody index, and various serum- and CSF-based indices.

RESULTS

Significantly elevated EBNA1 IgG levels were detected in serum and CSF of RRMS patients compared to HCs. CSF EBNA1 IgG and indices based on specific CSF EBNA1 IgG associated with CSF albumin or serum EBNA1 IgG associated with total serum IgG obtained the highest sensitivities and complemented the IgG index and oligoclonal bands.

CONCLUSION

These findings indicate that aforementioned indices may supplement existing indices and aid in the diagnosis of MS.

Oligoclonal bands

Oligoclonal bands (OCBs) represent the presence of intrathecal immunoglobulin G (IgG) as detected by isoelectric focusing and immunofixation. Cerebrospinal fluid (CSF) analysed alongside a paired serum sample gives five different immunofixation patterns. These are: type 1-the normal physiological state with no intrathecal IgG synthesis; type 2-evidence for intrathecal IgG synthesis, with CSF-restricted OCBs; type 3-evidence for intrathecal IgG synthesis, with CSF-restricted OCBs, but with additional, identical bands in the CSF and serum; type 4-absence of intrathecal IgG synthesis, but with identical OCBs in CSF and serum; and type 5-absence of intrathecal IgG synthesis, with a monoclonal band in CSF and serum. Analysis of these patterns can help to diagnose a range of neurological conditions, including multiple sclerosis. However, it is important to interpret OCB results alongside other CSF tests and their clinical context.

Advancements in Cerebrospinal Fluid Biosensors: Bridging the Gap from Early Diagnosis to the Detection of Rare Diseases

Cerebrospinal fluid (CSF) is a body fluid that can be used for the diagnosis of various diseases. However, CSF collection requires an invasive and painful procedure called a lumbar puncture (LP). This procedure is applied to any patient with a known risk of central nervous system (CNS) damage or neurodegenerative disease, regardless of their age range. Hence, this can be a very painful procedure, especially in infants and elderly patients. On the other hand, the detection of disease biomarkers in CSF makes diagnoses as accurate as possible. This review aims to explore novel electrochemical biosensing platforms that have impacted biomedical science. Biosensors have emerged as techniques to accelerate the detection of known biomarkers in body fluids such as CSF. Biosensors can be designed and modified in various ways and shapes according to their ultimate applications to detect and quantify biomarkers of interest. This process can also significantly influence the detection and diagnosis of CSF. Hence, it is important to understand the role of this technology in the rapidly progressing field of biomedical science.

Cerebrospinal fluid oligoclonal bands in Chinese patients with multiple sclerosis: the prevalence and its association with clinical features

Background

Cerebrospinal fluid oligoclonal band (CSF-OCB) is an established biomarker in diagnosing multiple sclerosis (MS), however, there are no nationwide data on CSF-OCB prevalence and its diagnostic performance in Chinese MS patients, especially in the virtue of common standard operation procedure (SOP).

Methods

With a consensus SOP and the same isoelectric focusing system, we conducted a nationwide multi-center study on OCB status in consecutively, and recruited 483 MS patients and 880 non-MS patients, including neuro-inflammatory diseases (NID, n = 595) and non-inflammatory neurological diseases (NIND, n=285). Using a standardized case report form (CRF) to collect the clinical, radiological, immunological, and CSF data, we explored the association of CSF-OCB positivity with patient characters and the diagnostic performance of CSF-OCB in Chinese MS patients. Prospective source data collection, and retrospective data acquisition and statistical data analysis were used.

Findings

369 (76.4%) MS patients were OCB-positive, while 109 NID patients (18.3%) and 6 NIND patients (2.1%) were OCB-positive, respectively. Time from symptom onset to diagnosis was significantly shorter in OCB-positive than that in OCB-negative MS patients (13.2 vs 23.7 months, P=0.020). The prevalence of CSF-OCB in Chinese MS patients was significantly higher in high-latitude regions (41°-50°N)(P=0.016), and at high altitudes (>1000m)(P=0.025). The diagnostic performance of CSF-OCB differentiating MS from non-MS patients yielded a sensitivity of 76%, a specificity of 87%.

Interpretation

The nationwide prevalence of CSF-OCB was 76.4% in Chinese MS patients, and demonstrated a good diagnostic performance in differentiating MS from other CNS diseases. The CSF-OCB prevalence showed a correlation with high latitude and altitude in Chinese MS patients.

Cerebrospinal Fluid-Basic Concepts Review

Cerebrospinal fluid plays a crucial role in protecting the central nervous system (CNS) by providing mechanical support, acting as a shock absorber, and transporting nutrients and waste products. It is produced in the ventricles of the brain and circulates through the brain and spinal cord in a continuous flow. In the current review, we presented basic concepts related to cerebrospinal fluid history, cerebrospinal fluid production, circulation, and its main components, the role of the blood-brain barrier and the blood-cerebrospinal fluid barrier in the maintenance of cerebrospinal fluid homeostasis, and the utility of Albumin Quotient (Q_Alb) evaluation in the diagnosis of CNS diseases. We also discussed the collection of cerebrospinal fluid (type, number of tubes, and volume), time of transport to the laboratory, and storage conditions. Finally, we briefly presented the role of cerebrospinal fluid examination in CNS disease diagnosis of various etiologies and highlighted that research on identifying cerebrospinal fluid biomarkers indicating disease presence or severity, evaluating treatment effectiveness, and enabling understanding of pathogenesis and disease mechanisms is of great importance. Thus, in our opinion, research on cerebrospinal fluid is still necessary for both the improvement of CNS disease management and the discovery of new treatment options.

Variation in Processes and Reporting of Cerebrospinal Fluid Oligoclonal Banding and Associated Tests and Calculated Indices across Canadian Clinical Laboratories

OBJECTIVES

Multiple sclerosis is diagnosed based on clinical and laboratory findings, including cerebrospinal fluid (CSF) oligoclonal banding (OCB) analysis. The lack of updated CSF OCB laboratory guidelines in Canada has likely led to variation in processes and reporting across clinical laboratories. As a first step to developing harmonized laboratory recommendations, we examined current CSF OCB processes, reporting, and interpretation across all Canadian clinical laboratories currently performing this test.

DESIGN AND METHODS

A survey of 39 questions was sent to clinical chemists at all 13 Canadian clinical laboratories performing CSF OCB analysis. The survey included questions regarding quality control processes, reporting practices for CSF gel electrophoresis pattern interpretation, and associated tests and calculated indices.

RESULTS

The survey response rate was 100%. Most (10/13) laboratories use ≥2 CSF-specific bands (2017 McDonald Criteria) as their CSF OCB positivity cut-off and only 2/13 report the number of bands with every report. Most (8/13 and 9/13) laboratories report an inflammatory response pattern and monoclonal gammopathy pattern, respectively. However, the process for reporting and/or confirming a monoclonal gammopathy varies widely. Variation was observed for reference intervals, units, and the panel of reported associated tests and calculated indices. The maximum acceptable time interval between paired CSF and serum collections varied from 24 hours to no limit.

CONCLUSIONS

Profound variation exists in processes, reporting, and interpretation of CSF OCB and associated tests and indices across Canadian clinical laboratories. Harmonization of CSF OCB analysis is required to ensure continuity and quality of patient care. Our detailed assessment of current practice variation highlights the need for clinical stakeholder engagement and further data analysis to support optimal interpretation and reporting practices, which will aid in developing harmonized laboratory recommendations.

Free light chains as a reliable biomarker of intrathecal synthesis in the diagnosis of CNS inflammatory diseases

OBJECTIVE

To address the diagnostic performances of cerebrospinal fluid (CSF) free light chains (FLC) measurements compared to oligoclonal bands (OCB) to support multiple sclerosis (MS) diagnosis.

RESULTS

kFLC index showed the highest diagnostic accuracy to detect MS patients with the highest AUC compared to OCB, IgG index, IF kFLC R, kFLC H, λFLC index and IF λFLC.

CONCLUSIONS

FLC indices are biomarkers of intrathecal Immunoglobulin synthesis and central nervous system (CNS) inflammation. kFLC index can discriminate between MS and other CNS inflammatory disorders, while λFLC index is less informative for MS but can play a role to support the diagnosis of other inflammatory CNS disorders.

An Updated Evaluation of Intrathecal IgG Synthesis Markers in Relation to Oligoclonal Bands

The aim was to evaluate the performance of the latest quantitative marker for intrathecal IgG synthesis and to compare it with other established markers used for the same purpose. We retrospectively applied Auer's and Reiber's intrathecal IgG synthesis formulae in a cohort of 372 patients under investigation for central nervous system demyelination who had undergone lumbar puncture and oligoclonal bands (OCBs) detection for demonstrating intrathecal IgG synthesis. A ROC analysis revealed Auer's formula had lower sensitivity (68%) compared to Reiber's formula (83%) and IgG index (89%), in our cohort of patients that exhibited normal to mildly elevated albumin quotients (4.48 ± 3.93). By excluding possible sources of errors, we assume that Auer's formula is less sensitive than other established tools for the "prediction" of the detection of OCBs in routine cerebrospinal fluid (CSF) analyses due to the mathematical model used. Given the ability of Reiber's hyperbolic formula to describe the blood-CSF IgG distribution across a wide range of blood-brain barrier functionality, its use and the use of similar formulae are recommended for the discrimination between CNS-derived and blood-derived molecules in clinical laboratories.

Sexual dimorphism in the cerebrospinal fluid total protein content

Objectives Cerebrospinal fluid (CSF) is a clear, colorless body fluid filling the central nervous system. The determination of the CSF total protein (TP) content represents an important screening test of various pathologies. We aimed to address the effect of sex and age on CSF-TP content and the use of the current upper reference limits (URLs). Methods CSF-TP content was analysed in a selected population of 1,252 patients (648 women and 604 men; age 18-89 years) who underwent lumbar puncture as a part of the diagnostic work-up. Samples presenting (i) more than 5 white blood cells (WBC)/µL, (ii) discolorations and (iii) reduced glucose were not included. Results The CSF-TP content median values were significantly higher in men than in women (46 vs. 37 mg/dL) even after adjusting for age and different hospital inpatients. CSF-TP content positively correlated with age both in men and in women with a constant difference between sexes of 8.5 mg/dL. Applying the most used URLs (mainly 45 and 50 mg/dL, but also 60 mg/dL), men received a laboratory report suggestive of altered CSF-TP content more frequently than women. The use of age- and sex-calibrated CSF-TP URLs reduced, but not eliminated, this sex-gap. Conclusions Using the current URLs, a condition of "elevated CSF-TP content" may be overestimated in men or, conversely, underestimated in women, regardless of the age and of the diagnosis. These results highlighted the need to apply CSF-TP URLs values ​​normalized for both sex and age.

Immune-Mediated Myelopathies: A Review of Etiologies, Diagnostic Approach, and Therapeutic Management

Myelopathy is a broad term used to describe a heterogeneous group of disorders that affects the spinal cord; the focus of this article will be a subgroup of these disorders with an autoimmune and inflammatory-based pathology. Symptoms typically develop over hours or days and then worsen over a matter of days to weeks, but sometimes can have a more insidious or subacute presentation, which can make the diagnosis more puzzling. Despite relatively low incidence rates, almost a third of affected patients are left with severely disabling symptoms. Prompt recognition of the underlying etiology is essential so that a specific targeted therapy can be implemented for optimal outcomes. The authors discuss a systematic approach to immune-mediated myelopathies, with a focus on the unique characteristics of each that may aid in diagnosis.

Sex-Related Differences in Cerebrospinal Fluid Plasma-Derived Proteins of Neurological Patients

Background and aims: Cerebrospinal fluid (CSF) protein content presents a sexual dimorphism in humans. We investigated sex-related differences in CSF IgG levels and in the quantification of intrathecal IgG synthesis (IIS). Methods: CSF, serum albumin and IgG were measured in 1519 neurological patients and both linear and hyperbolic formulas were used for the quantification of IIS. CSF-restricted oligoclonal IgG bands (OCBs) were used as “gold standard”. Results: The linear IgG Index showed a weak agreement with OCBs in males and females (k = 0.559, k = 0.587, respectively), while the hyperbolic Reiber’s formulas had a moderate agreement with OCBs in females (k = 0.635) and a weak agreement in males (k = 0.565). Higher CSF albumin and IgG levels were found in men than in women in the whole population and in subjects without IIS after adjusting for age and for serum concentrations of albumin and IgG, respectively (Quade statistics, p < 0.000001). CSF and serum albumin and IgG levels positively correlated to age in both sexes. CSF total protein content did not correlate with CSF leukocyte numbers but was higher in patients with marked pleocytosis. Conclusions: In neurological patients, men have higher levels of CSF serum-derived proteins, such as albumin and IgG.

Variation of membrane particle-bound CD133 in cerebrospinal fluid of patients with subarachnoid and intracerebral hemorrhage

OBJECTIVE

Previous studies have demonstrated that human CSF contains membrane particles carrying the stem cell antigenic marker CD133 (prominin-1). Here, the authors analyzed the variation of the amount of these CD133-positive particles in the CSF of patients with subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH).

METHODS

Consecutive CSF samples from 47 patients with SAH or ICH were compared to 14 healthy control patients. After differential ultracentrifugation of CSF, the membrane particle fraction was separated on gel electrophoresis and its CD133 content was probed by immunoblotting using the mouse monoclonal antibody 80B258 directed against human CD133. The antigen-antibody complexes were detected by chemiluminescence reagents and quantified using human Caco-2 cell extract as positive control with a standardized curve.

RESULTS

As compared to healthy controls (6.3 ± 0.5 ng of bound CD133 antibody; n = 14), the amount of membrane particle-associated CD133 immunoreactivities was significantly elevated in patients with SAH and ICH (38.2 ± 6.6 ng and 61.3 ± 11.0 ng [p < 0.001] for SAH [n = 18] and ICH [n = 29], respectively). In both groups the CD133 level dropped during the first 7 days (i.e., day 5-7: SAH group, 24.6 ± 10.1 ng [p = 0.06]; ICH group, 25.0 ± 4.8 ng [p = 0.002]). Whereas changes in the amount of CD133-positive membrane particles between admission and day 5-7 were not associated with clinical outcomes in patients with ICH (modified Rankin Scale [mRS] scores 0-3, -30.9 ± 12.8 ng vs mRS scores 4-6, -21.8 ± 10.7 ng; p = 0.239), persistent elevation of CD133 in patients with SAH was related to impaired functional outcome 3 months after ictus (mRS scores 0-2, -29.9 ± 8.1 ng vs mRS scores 3-6, 7.6 ± 20.3 ng; p = 0.027). These data are expressed as the mean ± standard error of the mean (SEM).

CONCLUSIONS

Levels of membrane particle-associated CD133 in the CSF of patients with SAH and ICH are significantly increased in comparison to healthy patients, and they decline during the hospital stay. Specifically, the persistent elevation of CD133-positive membrane particles within the first week may represent a possible surrogate measure for impaired functional outcome in patients with SAH.

Cerebrospinal fluid flow cytometry distinguishes psychosis spectrum disorders from differential diagnoses

Psychotic disorders are common and disabling mental conditions. The relative importance of immune-related mechanisms in psychotic disorders remains subject of debate. Here, we present a large-scale retrospective study of blood and cerebrospinal fluid (CSF) immune cell profiles of psychosis spectrum patients. We performed basic CSF analysis and multi-dimensional flow cytometry of CSF and blood cells from 59 patients with primary psychotic disorders (F20, F22, F23, and F25) in comparison to inflammatory (49 RRMS and 16 NMDARE patients) and non-inflammatory controls (52 IIH patients). We replicated the known expansion of monocytes in the blood of psychosis spectrum patients, that we identified to preferentially affect classical monocytes. In the CSF, we found a relative shift from lymphocytes to monocytes, increased protein levels, and evidence of blood-brain barrier disruption in psychosis. In fact, these CSF features confidently distinguished autoimmune encephalitis from psychosis despite similar (initial) clinical features. We then constructed machine learning models incorporating blood and CSF parameters and demonstrated their superior ability to differentiate psychosis from non-inflammatory controls compared to individual parameters. Multi-dimensional and multi-compartment immune cell signatures can thus support the diagnosis of psychosis spectrum disorders with the potential to accelerate diagnosis and initiation of therapy.

Anti-N-methyl-D-aspartate receptor encephalitis: a prospective study focused on cerebrospinal fluid and clinical symptoms

BACKGROUND AND OBJECTIVE

To analyze the relationship between brain MRI, clinical symptoms, and cerebrospinal fluid (CSF) and to provide a reference for early diagnosis of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis.

MATERIALS AND METHODS

A total of 62 patients with anti-NMDAR encephalitis in Zhengzhou, China (2016-2018) were observed and registered prospectively. First, we analyzed the characteristics of clinical symptoms. Second, according to the disease duration, patients were divided into two groups, and then we analyzed the CSF features. In addition, they were divided into two groups according to the brain MRI, and then the CSF features were analyzed. Finally, the characteristics of cerebrospinal fluid in patients with seizure as the initial symptom were analyzed.

RESULTS

Seizure presents as the initial symptom in 14 patients (22.5%), including 11 males (78.57%). The proportion and concentration of CSF total protein abnormalities in the early stage group were significantly higher than those in the middle and late group (P < 0.05). The total protein concentration in the abnormal brain MRI group was significantly higher than that in the normal MRI group (P < 0.05).

CONCLUSION

Anti-NMDAR encephalitis should be suspected, when male patients complain of seizure as an initial symptom and have simultaneously had headaches or fever prior to onset. The sensitivity of anti-NMDAR antibody is higher in CSF than in serum. Total CSF protein is more prone to elevation in the middle and late stages of anti-NMDAR encephalitis. Brain MRI abnormalities with anti-NMDAR encephalitis are related to the total protein concentration of CSF, which may be related to the disease duration.

Extreme Diversity of IgGs Against Histones, DNA, and Myelin Basic Protein in the Cerebrospinal Fluid and Blood of Patients with Multiple Sclerosis

It was recently shown that IgGs from sera of multiple sclerosis (MS) patients are active in the hydrolysis of DNA and myelin basic protein (MBP). We first analyzed the relative concentration of antibodies against five histones (H1, H2a, H2b, H3, and H4) in the cerebrospinal fluid (CSF) and serum of patients with MS. The relative concentrations of blood and CSF IgGs against histones and their activity in the hydrolysis of five histones varied greatly from patient to patient. However, all 28 IgG preparations were hydrolyzed from one to five histones. Relative activities and correlation coefficients among the activities of IgGs from serum and CSF in the hydrolysis of five histones (H1, H2a, H2b, H3, and H4), DNA, and MBP were calculated. It was shown that auto-IgGs from CSF and sera of MS patients are extremely heterogeneous in their affinity to histones, MBP, and DNA. The heterogeneity of IgG-abzymes hydrolyzing DNA, MBP, and histones from CSF and sera was also demonstrated using their isoelectrofocusing. The isofocusing profiles DNase, MBP-, and histone-hydrolyzing activities of IgGs may be very different for various individuals, but the total IgG subfractions with all their activities are distributed from pH 3 to 10.

Increased age and male sex are independently associated with higher frequency of blood-cerebrospinal fluid barrier dysfunction using the albumin quotient

Background

The cerebrospinal fluid (CSF)/serum quotient of albumin (QAlb) is the most used biomarker for the evaluation of blood–cerebrospinal fluid barrier (B-CSF-B) permeability. For years QAlb was considered only as an age-related parameter but recently it has also been associated to sex. The aim of the present study was to explore the impact of sex in the determination of B-CSF-B dysfunction.

Methods

The analysis was retrospectively conducted on subjects consecutively admitted to the neurological ward. CSF and serum albumin levels were measured by immunonephelometry and pathological QAlb thresholds were considered: 6.5 under 40 years, 8.0 in the age 40–60 and 9.0 over 60 years.

Results

1209 subjects were included in the study. 718 females and 491 males (age: 15–88 years): 24.6% of patients had a diagnosis of multiple sclerosis, 23.2% suffered from other inflammatory neurological diseases, 24.6% were affected by non-inflammatory neurological diseases, and for 27.6% of patients the final neurological diagnosis could not be traced. Dysfunctional B-CSF-B was detected more frequently (44 vs. 20.1%, p < 0.0001) and median QAlb value were higher (7.18 vs. 4.87, p < 0.0001) in males than in females in the overall study population and in all disease subgroups. QAlb and age were positively correlated both in female (p < 0.0001) and male (p < 0.0001) patients, however the slopes of the two regression lines were not significantly different (p = 0.7149), while the difference between the elevations was extremely significant (p < 0.0001) with a gap of 2.2 units between the two sexes. Finally, in a multivariable linear regression analysis increased age and male sex were independently associated with higher QAlb in the overall study population (both p < 0.001) and after stratification by age and disease group.

Conclusions

Accordingly, identification and validation of sex-targeted QAlb thresholds should be considered as a novel tool in an effort to achieve more precision in the medical approach.

Correlation between auto/mitophagic processes and magnetic resonance imaging activity in multiple sclerosis patients

Background

An alteration of autophagy and mitophagy, two highly conserved lysosome-dependent degradation pathways involved in the maintenance of cellular homeostasis, has been associated with multiple sclerosis (MS).

Objective

To search the level of autophagy-related 5 (ATG5) and Parkin proteins, as markers of autophagy and mitophagy respectively, and lactate in a cohort of MS patients.

Methods

Cerebrospinal fluid (CSF) and serum samples from 60 MS patients were analyzed: 30 with magnetic resonance imaging (MRI) evidence of disease activity, gadolinium (Gd)-based contrast agent positive (Gd+), and 30 without MRI evidence of disease activity (Gd−). ATG5, Parkin, and lactate were measured using commercially available products.

Results and conclusions

Serum levels of ATG5, Parkin, and lactate were more elevated in Gd+ than in Gd− MS patients (p < 0.0001), and CSF concentrations of ATG5 and Parkin were greater in Gd+ than in Gd− MS (p < 0.0001). Our results demonstrated that molecular markers of autophagy and mitophagy are increased in CSF of MS patients during the active phases of the disease and that these catabolic markers, together with lactate, are also remarkably augmented in blood suggesting a role of these processes in MS pathogenesis and the possible use of these molecules as biomarkers of disease activity.

Management of antibody-mediated autoimmune encephalitis in adults and children: literature review and consensus-based practical recommendations

Autoimmune encephalitis associated with antibodies against neuronal surface targets (NSAE) are rare but still underrecognized conditions that affect adult and pediatric patients. Clinical guidelines have recently been published with the aim of providing diagnostic clues regardless of antibody status. These syndromes are potentially treatable but the choice of treatment and its timing, as well as differential diagnoses, long-term management, and clinical and paraclinical follow-up, remain major challenges. In the absence of evidence-based guidelines, management of these conditions is commonly based on single-center expertise.Taking into account different published expert recommendations in addition to the multicenter experience of the Italian Working Group on Autoimmune Encephalitis, both widely accepted and critical aspects of diagnosis, management and particularly of immunotherapy for NSAE have been reviewed and are discussed.Finally, we provide consensus-based practical advice for managing hospitalization and follow-up of patients with NSAE.

K Index is a Reliable Marker of Intrathecal Synthesis, and an Alternative to IgG Index in Multiple Sclerosis Diagnostic Work-Up

The K free light chain (K) index has been suggested as a reliable marker of intrathecal synthesis, despite the 2017 McDonald criteria for multiple sclerosis (MS) suggesting to “interpret with caution positive immunoglobulin G (IgG) index when testing for oligoclonal bands (OB) is negative or not performed”. The aim of this study was to compare the performance of K and IgG indexes for MS diagnosis and OB detection in a cohort of Italian patients. We enrolled 385 patients (127 MS, 258 non-MS) who had cerebrospinal fluid (CSF) analysis, including isoelectric focusing (IEF), to detect OB in the diagnostic work-up. Albumin, IgG and free light chains were measured by nephelometry and used to calculate IgG and K indexes. Although the two markers were highly related (r = 0.75, r² = 0.55, p < 0.0001), the K index showed greater sensitivity and negative predictive value (versus the IgG index) for OB detection (97% versus 48% and 97% versus 71%) and MS diagnosis (96% versus 50% and 98% versus 78%). These results support K index (and not IgG index) as a first-line marker for MS, followed by IEF, according to a sequential testing approach in CSF analysis.

Multiplex Matrix Metalloproteinases Analysis in the Cerebrospinal Fluid Reveals Potential Specific Patterns in Multiple Sclerosis Patients

Background: Matrix metalloproteinases (MMPs) are pleiotropic enzymes involved in extracellular protein degradation and turnover. MMPs are implicated in the pathogenesis of many neurological diseases, including multiple sclerosis (MS).

Objective: To search the level of MMPs in the cerebrospinal fluid (CSF) of MS patients and detect possible disease-specific patterns.

Methods: CSF samples from 32 MS patients and, from 15 control subjects with other inflammatory neurological diseases (OIND) were analyzed. The Bio-Plex Pro Human MMP 9-Plex Panel (Bio-Rad) was used for the quantification of MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12, and MMP-13.

Results: CSF MMP-1 and MMP-12 levels were significantly reduced in MS as compared with OIND. In MS patients' CSF: (i) MMP-1 levels were significantly higher in women vs. men; (ii) MMP-10 concentrations were higher in patients with CSF-restricted IgG oligoclonal bands, and (iii) MMP-7 levels were increased in patients with longer disease duration. In the OIND group MMP-7 and MMP-12 levels significantly and directly correlated with age.

Conclusions: Our study contributes to investigating the role of MMPs in MS, with regard to CSF immunological features and disease duration. Sex-specific differences were also detected in MMPs CSF levels.

Cytokines in cerebrospinal fluid of patients with schizophrenia spectrum disorders: New data and an updated meta-analysis

Few studies have been conducted examining cytokines in cerebrospinal fluid of patients compared to healthy volunteers. The goals of this study were: 1) to report original data detailing cytokine levels in the cerebrospinal fluid (CSF) of 10 patients with a schizophrenia spectrum disorder (SSD) diagnosis and 10 healthy controls and 2) to conduct a meta-analysis of the available data on cytokine levels in the CSF of patients with SSD compared to healthy controls, including our new data. Cytokine concentrations were measured using the Q-plex Human Cytokine Screen array in CSF of 10 patients with SSD and 10 healthy volunteers. For the meta-analysis, an electronic PubMed and Google Scholar search without restrictions was conducted for articles that reported on cytokine levels in CSF in patients with an SSD compared to healthy controls. Our original data revealed statistically significant increases in levels of interleukin-8 (IL-8) and interleukin-1 beta (IL-1β) in the CSF of patients with an SSD compared to healthy volunteers. Our meta-analysis showed statistically significant increases in interleukin-6 (IL-6) and IL-8 in patients compared to healthy volunteers. Effect sizes between treated and untreated patients for IL-6 were of similar magnitude. However, IL-6 levels were higher in early stage schizophrenia patients compared to chronic schizophrenia patients. Studies with larger sample sizes, comprehensive assessments and ideally in the context of a randomized controlled intervention to minimize the impact of confounding factors are needed to fully understand the role of cytokines and inflammatory markers in the pathophysiology and treatment of schizophrenia.

Free Kappa light chains in neuroinflammatory disorders: Complement rather than substitute?

OBJECTIVES

The detection of cerebrospinal fluid (CSF)-specific IgG oligoclonal bands (OCB) by isoelectric focusing (IEF) is widely used to help diagnose inflammatory neurological disorders (IND), including multiple sclerosis. However, the quantification of free light chains (FLC) is increasingly evaluated as a surrogate method to determine the presence of an intrathecal inflammatory process. The objective of this study was to evaluate the diagnostic performance of kappa (κ) FLC measurement in comparison with OCB detection by IEF.

MATERIAL AND METHODS

We measured serum and CSF κFLCs by turbidimetry using the SPA_plus automated analyser and calculated the κ index in 142 samples from OCB-positive and negative MS, as well as from patients with inflammatory and non-inflammatory neurological disorders (IND and NIND).

RESULTS

The κFLC index was significantly increased in OCB-positive MS and IND patients versus OCB-negative patients. Its performance was relatively comparable to that of IEF for MS diagnosis. When using a κFLC index cutoff value of 6.29, sensitivity increased from 61.2% to 75.7% in comparison with IEF for diagnosing IND (P = .0051), with a slightly lower non-statistically significant specificity (82.1% vs 100%). When considering both OCB status positivity or a κFLC index superior to 6.29 to diagnose IND status, sensitivity raised to 80.6% (P < .05) with an equal specificity.

CONCLUSION

Our results demonstrate that the κFLC index does not discriminate MS from other IND patients, but is a reliable technique to detect intrathecal inflammation. However, κFLC quantification should probably be considered as a complementary method, rather than a substitute, to OCB detection.

Chemiluminescent detection of oligoclonal immunoglobulins after isoelectric focusing and affinity-mediated immunoblotting

BACKGROUND AND AIMS

Detection of oligoclonal IgG (o-IgG) in the cerebrospinal fluid (CSF) not found in serum is the principal laboratory test to support a diagnosis of multiple sclerosis. The aim of this study was to compare chemiluminescent and chromogenic detection of oligoclonal immunoglobulins in the cerebrospinal fluid and serum after their separation by means of isoelectric focusing followed by immunoblotting.

METHODS

A set of experiments was designed to detect oligoclonal immunoglobulins by means of alkaline phosphatase BCIP/NBT substrate and chemiluminescent peroxidase substrate.

RESULTS

Based on visual evaluation of signals, chemiluminescent detection requires about a 4 times lower amount of applied protein than very sensitive BCIP/NBT chromogenic detection. Very good correlation between methods has been shown for oligoclonal IgG. Antigen-specific oligoclonal IgG could be demonstrated by both methods although the pattern was clearer using chemiluminescence. In one patient, oligoclonal IgD bands barely visible by BCIP/NBT were convincingly demonstrated by chemiluminescence.

CONCLUSION

Chemiluminescent detection is a feasible option for oligoclonal immunoglobulin detection and could be used in cases when the sensitivity needs to be improved. Further studies and method optimisation are warranted.