Intrathecal oligoclonal IgG synthesis in multiple sclerosis

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.

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.

Uncovering alternative diagnoses in patients with clinical syndromes suggestive of multiple sclerosis: A transversal study from the prospective Barcelona CIS cohort

BACKGROUND

It is essential to exclude alternative diagnoses to diagnose multiple sclerosis (MS). However, detailed descriptions of alternative diagnoses in patients with suspected MS presenting with clinically isolated syndrome (CIS) are limited.

OBJECTIVES

To describe alternative diagnoses in patients presenting with CIS suggestive of MS.

METHODS

We conducted a descriptive analysis of patients from the Barcelona CIS cohort including subjects under 50 years of age with a CIS suggestive of MS but later diagnosed with conditions other than MS. We collected clinical, biological, and radiological data, and described the alternative etiologies identified.

RESULTS

Among 1468 patients in the Barcelona CIS cohort, 100 (6.8%) were diagnosed with an alternative condition. The most common neurological syndrome was optic neuritis (43.0%). Four patients (4.0%) had inflammatory-demyelinating lesions in at least two typical MS topographies on baseline magnetic resonance imaging (MRI), and 2 (2.0%) met the 2017 McDonald MS criteria. The most common etiologies were immune-mediated diseases (42.0%), especially MOGAD, followed by functional neurological disorders (15.0%) and vascular disease (10.0%).

CONCLUSION

The range of alternative diagnoses encountered during the MS diagnostic process highlights the need to rule out better explanations than MS. However, current MS diagnostic criteria effectively identify patients without MS in this context.

Advances in Diagnosis and Management of Atypical Demyelinating Diseases

The last two decades have seen tremendous progress in understanding central nervous system (CNS) demyelinating diseases, heralding an exciting new era for the diagnosis and treatment of patients with a variety of non-multiple sclerosis neuroinflammatory diseases. This article comprehensively reviews atypical CNS demyelinating diseases, beginning with the general approach to CNS demyelination, continuing with suggestions to facilitate the initial evaluation, and followed by a discussion about specific diseases (neuromyelitis optica, myelin oligodendrocyte glycoprotein antibody disease, acute disseminated encephalomyelitis, iatrogenic CNS demyelination, and transverse myelitis). MRI examples of these disorders are provided to illustrate key radiographic findings. The article concludes with recommendations for treatment.

CSF biomarkers of B-cell activation in multiple sclerosis: a clinical perspective

The role of B cells in the pathophysiology of multiple sclerosis (MS) extends beyond antibody synthesis, also involving the modulation of T lymphocytes and myeloid cells. B-cell activation within the Central Nervous System is associated with the release of various antibodies, cytokines, and chemokines, measurable in biofluids, thereby serving as biomarkers of the immune processes responsible for MS. To this purpose, a biomarker-based characterization of the disease through the combination of well-established markers, e.g., immunoglobulin (Ig) G index, IgG oligoclonal bands, Ig free light chains, with new promising markers, namely chemokine (C-X-C motif) ligand 13, and B-cell activating factor/A proliferation-inducing ligand, might represent a significant improvement in the management of people with MS.

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.

Measuring Disease Progression in Multiple Sclerosis Clinical Drug Trials and Impact on Future Patient Care

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system characterised by inflammation, demyelination and neurodegeneration. Although several drugs are approved for MS, their efficacy in progressive disease is modest. Addressing disease progression as a treatment goal in MS is challenging due to several factors. These include a lack of complete understanding of the pathophysiological mechanisms driving MS and the absence of sensitive markers of disease progression in the short-term of clinical trials. MS usually begins at a young age and lasts for decades, whereas clinical research often spans only 1-3 years. Additionally, there is no unifying definition of disease progression. Several drugs are currently being investigated for progressive MS. In addition to new medications, the rise of new technologies and of adaptive trial designs is enabling larger and more integrated data collection. Remote assessments and decentralised clinical trials are becoming feasible. These will allow more efficient and large studies at a lower cost and with less burden on study participants. As new drugs are developed and research evolves, we anticipate a concurrent change in patient care at various levels in the foreseeable future. We conducted a narrative review to discuss the challenges of accurately measuring disease progression in contemporary MS drug trials, some new research trends and their implications for patient care.

A survey of Canadian neurologists' perspectives and preferences for laboratory reporting of CSF oligoclonal banding

INTRODUCTION

Cerebrospinal fluid (CSF) oligoclonal banding (OCB) analysis aids in the diagnosis of multiple sclerosis (MS). Despite its clinical importance, there is profound variation in processes, reporting, and interpretation of CSF OCB and associated tests/indices across Canadian laboratories. This is likely due to the lack of clear, evidence-based recommendations on CSF OCB analysis processes and reporting. Here, we assessed the CSF OCB reporting needs and preferences of Canadian neurologists as a first step in clinical stakeholder engagement to aid in the development of CSF OCB reporting recommendations.

METHODS

A 16-question survey was sent to neurologists across Canada in January 2022, and it closed in March 2022. The survey included questions regarding location and length of clinical practice; preferred maximum time limit for paired CSF and serum samples; reporting preferences for CSF-specific OCB, banding patterns, and associated tests/indices; as well as the clinical utility of CSF OCB and associated tests/indices.

RESULTS

Twenty-two neurologists from nine provinces participated, with a median practice length of 13 years. Most (64 %) preferred a 24-hour limit for paired serum and CSF sample collection. The majority (73 %) favored a cutoff of ≥ 2 CSF-specific bands for positivity, aligning with the 2017 McDonald criteria. Opinions varied on reporting the number of bands and listing specific conditions in the interpretive comments. Some highlighted the need for further research on band count interpretation and its clinical implications. All respondents found CSF OCB results useful, with 64 % valuing it more than other CSF tests for MS evaluation.

CONCLUSIONS

Our survey reveals diverse preferences among Canadian neurologists for CSF OCB reporting. Stakeholder engagement and further research are crucial for standardized, improved MS diagnostic practices.

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.

Multiple Sclerosis: From the Application of Oligoclonal Bands to Novel Potential Biomarkers

Multiple sclerosis is a chronic immune-mediated disorder of the central nervous system with a high heterogeneity among patients. In the clinical setting, one of the main challenges is a proper and early diagnosis for the prediction of disease activity. Current diagnosis is based on the integration of clinical, imaging, and laboratory results, with the latter based on the presence of intrathecal IgG oligoclonal bands in the cerebrospinal fluid whose detection via isoelectric focusing followed by immunoblotting represents the gold standard. Intrathecal synthesis can also be evidenced by the measurement of kappa free light chains in the cerebrospinal fluid, which has reached similar diagnostic accuracy compared to that of oligoclonal bands in the identification of patients with multiple sclerosis; moreover, recent studies have also highlighted its value for early disease activity prediction. This strategy has significant advantages as compared to using oligoclonal band detection, even though some issues remain open. Here, we discuss the current methods applied for cerebrospinal fluid analysis to achieve the most accurate diagnosis and for follow-up and prognosis evaluation. In addition, we describe new promising biomarkers, currently under investigation, that could contribute both to a better diagnosis of multiple sclerosis and to its monitoring of the therapeutic treatment response.

An autoantibody signature predictive for multiple sclerosis

Although B cells are implicated in multiple sclerosis (MS) pathophysiology, a predictive or diagnostic autoantibody remains elusive. In this study, the Department of Defense Serum Repository (DoDSR), a cohort of over 10 million individuals, was used to generate whole-proteome autoantibody profiles of hundreds of patients with MS (PwMS) years before and subsequently after MS onset. This analysis defines a unique cluster in approximately 10% of PwMS who share an autoantibody signature against a common motif that has similarity with many human pathogens. These patients exhibit antibody reactivity years before developing MS symptoms and have higher levels of serum neurofilament light (sNfL) compared to other PwMS. Furthermore, this profile is preserved over time, providing molecular evidence for an immunologically active preclinical period years before clinical onset. This autoantibody reactivity was validated in samples from a separate incident MS cohort in both cerebrospinal fluid and serum, where it is highly specific for patients eventually diagnosed with MS. This signature is a starting point for further immunological characterization of this MS patient subset and may be clinically useful as an antigen-specific biomarker for high-risk patients with clinically or radiologically isolated neuroinflammatory syndromes.

Association between clinical characteristics, acute steroid treatment and oligoclonal bands result in multiple sclerosis: A retrospective study

BACKGROUND

Detection of oligoclonal bands (OCBs) in the cerebrospinal fluid (CSF) is important for diagnosis of multiple sclerosis (MS). Previous studies reported that treatment with intravenous methylprednisolone (IVMP) before lumber puncture (LP) could suppress OCBs production. The aim of this study was to assess whether IVMP initiation prior to CSF collection affects OCBs results in patients with an acute demyelinating event. Additionally, we examined which clinical characteristics are associated with the presence of OCBs in the CSF.

METHODS

We retrospectively evaluated patients admitted to the neurology department at rabin medical center (RMC) between 2010 and 2022 who underwent LP with OCBs analysis as part of their demyelinating attack workup. Patients were divided into OCB-positive and OCB-negative groups and demographical and clinical characteristics (including timing and duration of acute steroid treatment and history of prior demyelinating attacks) were analyzed for association with OCBs results.

RESULTS

A total of 342 patients were included with a median age of 35 years (IQR, 27-46). Two hundred thirty-eight (69.6 %) were OCB-positive. Initiation of IVMP before LP was not associated with negative OCBs (11.8 % Vs. 13.5 %, P = 0.721), nor was it correlated with OCBs positivity (OR=0.86, P = 0.66). CSF cell count was higher in OCB-positive patients (5 Vs. 3, P = 0.001), and a history of prior demyelinating attacks was associated with- (33.6 % Vs. 20.2 %, P = 0.014) and predictive of OCBs positivity (OR=2, P = 0.013).

CONCLUSIONS

Timing of steroids was not associated with OCB positivity. However, pleocytosis and a prior attack were associated with OCB positivity in this cohort. Our results suggest that steroid treatment is unlikely to affect OCBs results. Ideally, larger prospective studies would be needed to confirm our observations.

Infrequent patterns in cerebrospinal fluid isofocusing test: Clinical significance and contribution of IgG index and Reiber diagram to their interpretation

Cerebrospinal fluid (CSF) isoelectrofocusing (IEF) is considered as the gold standard for detecting an intrathecal synthesis of IgG, which is a hallmark of multiple sclerosis (MS). This corresponds to the presence of CSF-restricted IgG oligoclonal bands (OCB) (typically type 2 pattern). Moreover, this technique can also detect a systemic immune reaction with passive transfer of IgG (type 3 and 4 patterns) for which the clinical relevance is less understood. The aim of our study was to determine the frequency and disease associations of IEF type 3 and 4 patterns and to investigate the potential usefulness of including quantitative data (IgG index and Reiber Diagram) in interpreting such IEF profiles. Among 544 patients who underwent CSF IEF (Hydragel CSF isofocusing kit, Sebia®, France) in our Laboratory during a six-year-period, those who presented type 3 or 4 patterns were selected. Clinical data and results of other immunological tests were analyzed for 27 patients followed in the Neurological Department. Frequencies of type 3 and type 4 patterns were relatively low (2.3 % and 3.4 % respectively). Among patients with type 3 pattern included in our study (n = 10), 5 were diagnosed with MS. For the 5 other patients, the diagnosis was a clinically isolated syndrome (CIS) (2 cases), a probable auto-immune encephalitis (2 cases) and a possible genetic neurodegenerative disease (1 case). MS patients had an IgG index >0.7 and fell into area 4 of Reiber diagram while non-MS patients had an IgG index <0.7 and fell into area 1, except the last case. Regarding type 4 pattern (n = 17), the diagnoses were as follows: MS (3), CIS (4), Neuromyelitis optica spectrum disorders with positive anti-AQP4 antibodies (3) and anti-NMDAR autoimmune encephalitis (1). The remaining cases had central nervous system impairment related to vascular, metabolic or tumoral etiologies (3) or peripheral nervous system impairment (3). In this group (type 4 pattern), IgG index was <0.7 in 15/17 cases. Interpretation using Reiber diagram showed an abnormal blood-brain barrier for 8/17 patients. Type 3 and 4 IEF patterns are infrequently observed in routine neurology practice. It is important for the diagnostic laboratory professional as well as for the neurologist to understand their clinical relevance. Our findings highlight the contribution of quantitative evaluation of CSF (IgG index, Reiber diagram) for the interpretation of such situations. Despite the small size of our study population, our results emphasize the importance of reporting the exact type of IEF pattern and not only the positivity or not of OCB.

Body fluid markers for multiple sclerosis and differential diagnosis from atypical demyelinating disorders

INTRODUCTION

Body fluid markers could be helpful to predict the conversion into clinically definite multiple sclerosis (MS) in people with a first demyelinating event of the central nervous system (CNS). Consequently, biomarkers such as oligoclonal bands, which are integrated in the current MS diagnostic criteria, could assist early MS diagnosis.

AREAS COVERED

This review examines existing knowledge on a broad spectrum of body fluid markers in people with a first CNS demyelinating event, explores their potential to predict conversion to MS, to assess MS disease activity, as well as their utility to differentiate MS from atypical demyelinating disorders such as neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disease.

EXPERT OPINION

This field of research has shown a dramatic increase of evidence, especially in the last decade. Some biomarkers are already established in clinical routine (e.g. oligoclonal bands) while others are currently implemented (e.g. kappa free light chains) or considered as breakthroughs (e.g. neurofilament light). Determination of biomarkers poses challenges for continuous monitoring, especially if exclusively detectable in cerebrospinal fluid. A handful of biomarkers are measurable in blood which holds a significant potential.

CXCL10/IgG1 Axis in Multiple Sclerosis as a Potential Predictive Biomarker of Disease Activity

BACKGROUND AND OBJECTIVES

Multiple sclerosis (MS) is a heterogeneous disease, and its course is difficult to predict. Prediction models can be established by measuring intrathecally synthesized proteins involved in inflammation, glial activation, and CNS injury.

METHODS

To determine how these intrathecal proteins relate to the short-term, i.e., 12 months, disease activity in relapsing-remitting MS (RRMS), we measured the intrathecal synthesis of 46 inflammatory mediators and 14 CNS injury or glial activation markers in matched serum and CSF samples from 47 patients with MS (pwMS), i.e., 23 RRMS and 24 clinically isolated syndrome (CIS), undergoing diagnostic lumbar puncture. Subsequently, all pwMS were followed for ≥12 months in a retrospective follow-up study and ultimately classified into "active", i.e., developing clinical and/or radiologic disease activity, n = 18) or "nonactive", i.e., not having disease activity, n = 29. Disease activity in patients with CIS corresponded to conversion to RRMS. Thus, patients with CIS were subclassified as "converters" or "nonconverters" based on their conversion status at the end of a 12-month follow-up. Twenty-seven patients with noninflammatory neurologic diseases were included as negative controls. Data were subjected to differential expression analysis and modeling techniques to define the connectivity arrangement (network) between neuroinflammation and CNS injury relevant to short-term disease activity in RRMS.

RESULTS

Lower age and/or higher CXCL13 levels positively distinguished active/converting vs nonactive/nonconverting patients. Network analysis significantly improved the prediction of short-term disease activity because active/converting patients featured a stronger positive connection between IgG1 and CXCL10. Accordingly, analysis of disease activity-free survival demonstrated that pwMS, both RRMS and CIS, with a lower or negative IgG1-CXCL10 correlation, have a higher probability of activity-free survival than the patients with a significant correlation (p < 0.0001, HR ≥ 2.87).

DISCUSSION

Findings indicate that a significant IgG1-CXCL10 positive correlation predicts the risk of short-term disease activity in patients with RRMS and CIS. Thus, the present results can be used to develop a predictive model for MS activity and conversion to RRMS.

The role of oligoclonal band count and IgG index in treatment response and disease activity in multiple sclerosis

BACKGROUND/AIM

Multiple sclerosis (MS) is an inflammatory demyelinating central nervous system (CNS) disease. Among the paraclinical tests, brain and spinal Magnetic Resonance Imaging (MRI) is primarily involved in the diagnosis process, and cerebrospinal fluid (CSF) analysis is fundamental in diagnosing MS and the differential diagnosis. A positive relationship was demonstrated between oligoclonal band (OCB) positivity, CSF band number and immunoglobulin G(IgG) index. The study aimed to evaluate whether the number of OCB can predict disease activity and determine a correlation with the IgG index.

METHODS

Our study included 401 MS patients who had relapsing-remitting multiple sclerosis (RRMS), primary progressive multiple sclerosis (PPMS), secondary progressive multiple sclerosis (SPMS), clinic isolated syndrome (CIS), radiologic isolated syndrome (RIS), Neuromyelitis optica spectrum disorder (NMOSD) and Acute disseminated encephalomyelitis (ADEM) with OCB number groups of 2-4, 4-8, 8-12, and 12 and above.

RESULTS

No significant correlation was observed between IgG index, pre-and post-treatment EDSS (Expanded Disability Status Scale Scores) and disease-modifying therapies (DMT). Drug response was better in the patient group with band number between 2 and 8 and post-treatment EDSS scores were lower (1.62±0.44).

CONCLUSION

The study results suggested that band number may be as valuable as the IgG index and a predictive biomarker for disease activity.

Understanding immune microenvironment alterations in the brain to improve the diagnosis and treatment of diverse brain diseases

Abnormal inflammatory states in the brain are associated with a variety of brain diseases. The dynamic changes in the number and function of immune cells in cerebrospinal fluid (CSF) are advantageous for the early prediction and diagnosis of immune diseases affecting the brain. The aggregated factors and cells in inflamed CSF may represent candidate targets for therapy. The physiological barriers in the brain, such as the blood‒brain barrier (BBB), establish a stable environment for the distribution of resident immune cells. However, the underlying mechanism by which peripheral immune cells migrate into the brain and their role in maintaining immune homeostasis in CSF are still unclear. To advance our understanding of the causal link between brain diseases and immune cell status, we investigated the characteristics of immune cell changes in CSF and the molecular mechanisms involved in common brain diseases. Furthermore, we summarized the diagnostic and treatment methods for brain diseases in which immune cells and related cytokines in CSF are used as targets. Further investigations of the new immune cell subtypes and their contributions to the development of brain diseases are needed to improve diagnostic specificity and therapy.

An update on the role of magnetic resonance imaging in predicting and monitoring multiple sclerosis progression

INTRODUCTION

While magnetic resonance imaging (MRI) is established in diagnosing and monitoring disease activity in multiple sclerosis (MS), its utility in predicting and monitoring disease progression is less clear.

AREAS COVERED

The authors consider changing concepts in the phenotypic classification of MS, including progression independent of relapses; pathological processes underpinning progression; advances in MRI measures to assess them; how well MRI features explain and predict clinical outcomes, including models that assess disease effects on neural networks, and the potential role for machine learning.

EXPERT OPINION

Relapsing-remitting and progressive MS have evolved from being viewed as mutually exclusive to having considerable overlap. Progression is likely the consequence of several pathological elements, each important in building more holistic prognostic models beyond conventional phenotypes. MRI is well placed to assess pathogenic processes underpinning progression, but we need to bridge the gap between MRI measures and clinical outcomes. Mapping pathological effects on specific neural networks may help and machine learning methods may be able to optimize predictive markers while identifying new, or previously overlooked, clinically relevant features. The ever-increasing ability to measure features on MRI raises the dilemma of what to measure and when, and the challenge of translating research methods into clinically useable tools.

A comparison of measles-rubella-zoster reaction, oligoclonal IgG bands, oligoclonal kappa free light chains and kappa index in multiple sclerosis

BACKGROUND AND OBJECTIVES

To evaluate the diagnostic performance of the measles-rubella-zoster reaction (MRZR) in a large real-world multiple sclerosis (MS) cohort. Second, to compare MRZR with the determination of oligoclonal IgG bands (OCB), oligoclonal kappa free light chain bands (oKFLC), and the KFLC index.

METHODS

A single-center retrospective study was conducted at the University Hospital Ostrava (Czech Republic). Patients were eligible if aged ≥18 years with a determined clinical diagnosis. IgG antibodies against measles (M), rubella (R), and varicella zoster (Z) viruses were determined in paired CSF and serum using ELISA and MRZR indicated as positive if at least two components had an antibody index >1.4. OCB and oKFLC were detected by means of isoelectric focusing, and KFLC CSF and serum concentrations for calculation of the KFLC index were determined immunochemically.

RESULTS

A total of 1,751 patients were included in the analyzed data set, which comprised 379 MS patients and 1,372 non-MS controls. The frequency of positive MRZR was higher in MS than in non-MS cases (MS 32.2 % vs non-MS 2.8 %; p < 0.001). This corresponded to a specificity of 97.2 % (95 % CI 96.1-98.0) and sensitivity of 32.2 % (95 % CI 27.5-37.2) and overall accuracy of 83.1 % (95 % CI 81.3-84.8). In comparison, the highest sensitivity of 95.6% (95 % CI 93.0-97.5) was for OCB with specificity of 86.9 % (95 % CI 84.9-88.7), followed by oKFLC with sensitivity and specificity of 94.7 % (95 % CI 91.5-96.9) and 78.4% (95 % CI 75.7-80.8), respectively, and the KFLC index with sensitivity of 92.5 % (95 % CI 86.6-96.3) and specificity of 93.5 % (95 % CI 90.5-95.9).

DISCUSSION

MRZR remains a very specific test for the diagnosis of MS but has low sensitivity, which disallows its independent use. In contrast, OCB showed the highest sensitivity and thus remains the gold standard for the diagnosis of MS.

A dynamic interpretation of κFLC index for the diagnosis of multiple sclerosis: a change of perspective

BACKGROUND

Previous studies attempted to define the best threshold for κ free light chains (κFLC) index, confirming higher sensitivity (Se) but less specificity (Sp) compared with IgG oligoclonal bands (OCB) for the diagnosis of MS.

OBJECTIVE

To evaluate the diagnostic accuracy of different κFLC index intervals in a miscellaneous cohort of neurological patients, proposing a procedural flowchart for MS diagnosis.

METHODS

We analyzed data from 607 patients diagnosed with MS (179), CIS (116), other inflammatory (94) or non-inflammatory neurological diseases (218). Measures of diagnostic accuracy were reported for different potential thresholds of κFLC index, and for IgG OCB and IgG index. Binary logistic regression was to used to calculate the odds of being diagnosed with MS based on each increase of κFLC index.

RESULTS

CSF IgG OCB showed 72.2% Se (CI 95% 68.4-75.7) and 95.2% Sp (CI 95% 93.1-96.7) in discriminating between MS/CIS and controls, with an AUC of 0.84 (CI 95% 0.80-0.87). The highest diagnostic accuracy was reported for κFLC index cut-off of 5.0 (Se = 85.4%, Sp = 90.4%, AUC = 0.88), while a threshold of 11.0 exhibited higher Sp (95.5%, 95% CI 93.1-97.1) than IgG OCB. AUCs for all thresholds between 4.25 and 6.6 were not significantly different from each other, but were significantly higher than the AUC of IgG OCB (p < 0.05). The odds of being diagnosed with MS/CIS increased by 17.1% for each unit increase of κFLC index (OR = 1.17; 95% CI 1.12-1.23; p < 0.001).

CONCLUSION

κFLC index performed better than CSF IgG OCB in supporting the diagnosis of MS/CIS, with the advantage of being a cost-effective and quantitative analysis.

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.

From Recognition to Remedy: The Significance of Biomarkers in Neurodegenerative Disease Pathology

With the inexorable aging of the global populace, neurodegenerative diseases (NDs) like Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) pose escalating challenges, which are underscored by their socioeconomic repercussions. A pivotal aspect in addressing these challenges lies in the elucidation and application of biomarkers for timely diagnosis, vigilant monitoring, and effective treatment modalities. This review delineates the quintessence of biomarkers in the realm of NDs, elucidating various classifications and their indispensable roles. Particularly, the quest for novel biomarkers in AD, transcending traditional markers in PD, and the frontier of biomarker research in ALS are scrutinized. Emergent susceptibility and trait markers herald a new era of personalized medicine, promising enhanced treatment initiation especially in cases of SOD1-ALS. The discourse extends to diagnostic and state markers, revolutionizing early detection and monitoring, alongside progression markers that unveil the trajectory of NDs, propelling forward the potential for tailored interventions. The synergy between burgeoning technologies and innovative techniques like -omics, histologic assessments, and imaging is spotlighted, underscoring their pivotal roles in biomarker discovery. Reflecting on the progress hitherto, the review underscores the exigent need for multidisciplinary collaborations to surmount the challenges ahead, accelerate biomarker discovery, and herald a new epoch of understanding and managing NDs. Through a panoramic lens, this article endeavors to provide a comprehensive insight into the burgeoning field of biomarkers in NDs, spotlighting the promise they hold in transforming the diagnostic landscape, enhancing disease management, and illuminating the pathway toward efficacious therapeutic interventions.

Cerebrospinal fluid soluble CD27 is associated with CD8+ T cells, B cells and biomarkers of B cell activity in relapsing-remitting multiple sclerosis

Cerebrospinal fluid (CSF) soluble CD27 (sCD27) is a sensitive biomarker of intrathecal inflammation. Although generally considered a biomarker of T cell activation, CSF sCD27 has been shown to correlate with biomarkers of B cell activity in multiple sclerosis. We analyzed CSF from 40 patients with relapsing-remitting multiple sclerosis (RRMS) and nine symptomatic controls using flow cytometry and multiplex electrochemiluminescence immunoassays. CSF sCD27 levels were increased in RRMS and correlated with IgG index, soluble B cell maturation antigen, cell count, B cell frequency and CD8+ T cell frequency. We provide new data indicating that CSF sCD27 is associated with CD8+ T cells and B cells in RRMS.

Emerging imaging and liquid biomarkers in multiple sclerosis

The advent of highly effective disease modifying therapy has transformed the landscape of multiple sclerosis (MS) care over the last two decades. However, there remains a critical, unmet need for sensitive and specific biomarkers to aid in diagnosis, prognosis, treatment monitoring, and the development of new interventions, particularly for people with progressive disease. This review evaluates the current data for several emerging imaging and liquid biomarkers in people with MS. MRI findings such as the central vein sign and paramagnetic rim lesions may improve MS diagnostic accuracy and evaluation of therapy efficacy in progressive disease. Serum and cerebrospinal fluid levels of several neuroglial proteins, such as neurofilament light chain and glial fibrillary acidic protein, show potential to be sensitive biomarkers of pathologic processes such as neuro-axonal injury or glial-inflammation. Additional promising biomarkers, including optical coherence tomography, cytokines and chemokines, microRNAs, and extracellular vesicles/exosomes, are also reviewed, among others. Beyond their potential integration into MS clinical care and interventional trials, several of these biomarkers may be informative of MS pathogenesis and help elucidate novel targets for treatment strategies.

Biochemical biomarkers for multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is the most frequent demyelinating disease of the central nervous system. Although there is currently no definite cure for MS, new therapies have recently been developed based on a continuous search for new biomarkers.

DEVELOPMENT

MS diagnosis relies on the integration of clinical, imaging and laboratory findings as there is still no singlepathognomonicclinical feature or diagnostic laboratory biomarker. The most commonly laboratory test used is the presence of immunoglobulin G oligoclonal bands (OCB) in cerebrospinal fluid of MS patients. This test is now included in the 2017 McDonald criteria as a biomarker of dissemination in time. Nevertheless, there are other biomarkers currently in use such as kappa free light chain, which has shown higher sensitivity and specificity for MS diagnosis than OCB. In addition, other potential laboratory tests involved in neuronal damage, demyelination and/or inflammation could be used for detecting MS.

CONCLUSIONS

CSF and serum biomarkers have been reviewed for their use in MS diagnosis and prognosis to stablish an accurate and prompt MS diagnosis, crucial to implement an adequate treatment and to optimize clinical outcomes over time.

The Interpretation of Mirror Pattern Bands During Oligoclonal Immunoglobulin Isoelectric Focusing Electrophoresis: A Retrospective Study

OBJECTIVE

Mirror patterns are incidental types that accompany the analysis of the oligoclonal band (OCB) in cerebrospinal fluid (CSF). However, their interpretation remains controversial. In this study, we analyzed all graphic results of mirror patterns from 86 patients to provide an optimal interpretation scheme for mirror patterns.

METHODS

Matched CSF and serum specimens were obtained from patients with various neurological disorders that required OCB analysis. A total of 86 patients were screened and serum immunofixation electrophoresis (IFE) was performed in all 86. The interobserver agreement for interpreting mirror patterns by visual inspection was tested. The method agreement between the visual inspection and IFE was also evaluated. The CSF/serum albumin quotient (QALB) was calculated to determine the blood-brain barrier integrity of all patients.

RESULTS

Of the 86 patients with mirror patterns, 19.8% (17/86) had typical mirror bands and most (80.2%) had atypical mirror bands. There was a good agreement between the 2 observers in interpreting typical mirror patterns. However, kappa statistics analysis showed poor agreement regarding the interpretation of atypical mirror bands by visual observation alone (kappa value, -0.026 to 0.314 between 2 observers). The disagreement was pronounced between the visual inspection and validation of IFE (kappa value, -0.0238 to 0.176 between the first observer and IFE; -0.322 to 0.118 between the second observer and IFE). The normal QALB rates in the type V groups were significantly higher than those in the type IV group and the positive QALB rates in the type IV were significantly higher than those in the type V.

CONCLUSION

Visual inspection to interpret mirror pattern bands is unreliable. Considering the completely different clinical significance between type IV and type V and high risk of potential misinterpretations, it is necessary to perform IFE on all the atypical mirror types to discriminate atypical type IV from atypical type V.

The Role of Clinical Assessment in the Era of Biomarkers

Hippocratic Medicine revolved around the three main principles of patient, disease, and physician and promoted the systematic observation of patients, rational reasoning, and interpretation of collected information. Although these remain the cardinal features of clinical assessment today, Medicine has evolved from a more physician-centered to a more patient-centered approach. Clinical assessment allows physicians to encounter, observe, evaluate, and connect with patients. This establishes the patient-physician relationship and facilitates a better understanding of the patient-disease relationship, as the ultimate goal is to diagnose, prognosticate, and treat. Biomarkers are at the core of the more disease-centered approach that is currently revolutionizing Medicine as they provide insight into the underlying disease pathomechanisms and biological changes. Genetic, biochemical, radiographic, and clinical biomarkers are currently used. Here, we define a seven-level theoretical construct for the utility of biomarkers in neurodegenerative diseases. Level 1-3 biomarkers are considered supportive of clinical assessment, capable of detecting susceptibility or risk factors, non-specific neurodegeneration or dysfunction, and/or changes at the individual level which help increase clinical diagnostic accuracy and confidence. Level 4-7 biomarkers have the potential to surpass the utility of clinical assessment through detection of early disease stages and prediction of underlying pathology. In neurodegenerative diseases, biomarkers can potentiate, but cannot substitute, clinical assessment. In this current era, aside from adding to the discovery, evaluation/validation, and implementation of more biomarkers, clinical assessment remains crucial to maintaining the personal, humanistic, and sociocultural aspects of patient care. We would argue that clinical assessment is a custom that should never go obsolete.

A Predictive Autoantibody Signature in Multiple Sclerosis

Although B cells are implicated in multiple sclerosis (MS) pathophysiology, a predictive or diagnostic autoantibody remains elusive. Here, the Department of Defense Serum Repository (DoDSR), a cohort of over 10 million individuals, was used to generate whole-proteome autoantibody profiles of hundreds of patients with MS (PwMS) years before and subsequently after MS onset. This analysis defines a unique cluster of PwMS that share an autoantibody signature against a common motif that has similarity with many human pathogens. These patients exhibit antibody reactivity years before developing MS symptoms and have higher levels of serum neurofilament light (sNfL) compared to other PwMS. Furthermore, this profile is preserved over time, providing molecular evidence for an immunologically active prodromal period years before clinical onset. This autoantibody reactivity was validated in samples from a separate incident MS cohort in both cerebrospinal fluid (CSF) and serum, where it is highly specific for patients eventually diagnosed with MS. This signature is a starting point for further immunological characterization of this MS patient subset and may be clinically useful as an antigen-specific biomarker for high-risk patients with clinically- or radiologically-isolated neuroinflammatory syndromes.

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.

CSF oligoclonal IgG bands are not associated with ALS progression and prognosis

Introduction

Amyotrophic Lateral Sclerosis (ALS) is characterized by progressive motoneuron degeneration through cell autonomous and non-cell autonomous mechanisms; and the involvement of the innate and adaptive immune system has been hypothesized based on human and murine model data. We have explored if B-cell activation and IgG responses, as detected by IgG Oligoclonal bands (OCB) in serum and cerebrospinal fluid, were associated with ALS or with a subgroup of patients with distinct clinical features.

Methods

IgG OCB were determined in patients affected by ALS (n=457), Alzheimer Disease (n=516), Mild Cognitive Impairment (n=91), Tension-type Headache (n=152) and idiopathic Facial Palsy (n=94). For ALS patients, clinico-demographic and survival data were prospectively collected in the Register Schabia.

Results

The prevalence of IgG OCB is comparable in ALS and the four neurological cohorts. When the OCB pattern was considered (highlighting either intrathecal or systemic B-cells activation), no effect of OCB pattern on clinic-demographic parameters and overall. ALS patients with intrathecal IgG synthesis (type 2 and 3) were more likely to display infectious, inflammatory or systemic autoimmune conditions.

Discussion

These data suggest that OCB are not related to ALS pathophysiology but rather are a finding possibly indicative a coincidental infectious or inflammatory comorbidity that merits further investigation.

Assessment of oligoclonal bands in cerebrospinal fluid and serum of dogs with meningoencephalitis of unknown origin

BACKGROUND

Meningoencephalitis of unknown origin (MUO) is an inflammatory disease of the canine central nervous system (CNS) that shares several features with multiple sclerosis (MS) in humans. In approximately 95% of MS patients, ≥ two immunoglobulin G (IgG) oligoclonal bands (OCBs) are detectable exclusively in the cerebrospinal fluid (CSF).

HYPOTHESIS/OBJECTIVES

To investigate OCBs in CSF and serum in dogs affected by MUO, intervertebral disc disease (IVDD), idiopathic epilepsy (IE), intracranial neoplasia (IN), steroid-responsive meningitis-arteritis (SRMA), and diseases outside the CNS. We hypothesize that the highest prevalence of CSF-specific OCBs (≥ two OCBs uniquely in the CSF) would be found in dogs affected by MUO.

ANIMALS

Client-owned dogs (n = 121) presented to the neurology service due to neurological deficits.

METHODS

Prospective study. Measurement of IgG concentration in CSF and serum via a canine IgG ELISA kit. OCB detection via isoelectric focusing (IEF) and immunoblot.

RESULTS

Presence of CSF-specific OCBs was significantly higher in dogs with MUO (57%) compared to 22% in IN, 6% in IE, 15% in SRMA, 13% in IVDD, and 0% in the non-CNS group (p < .001). Dogs with MUO were 9.9 times more likely to show CSF-specific OCBs than all other diseases together (95% confidence interval, 3.7-26.4; p < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

MUO showed the highest prevalence of CSF-specific OCBs, indicating an inflammatory B cell response. Future studies are needed to evaluate the prevalence in the specific MUO subtypes and a possible similarity with human MS.

Neurodegeneration in multiple sclerosis

Axonal loss in multiple sclerosis (MS) is a key component of disease progression and permanent neurologic disability. MS is a heterogeneous demyelinating and neurodegenerative disease of the central nervous system (CNS) with varying presentation, disease courses, and prognosis. Immunomodulatory therapies reduce the frequency and severity of inflammatory demyelinating events that are a hallmark of MS, but there is minimal therapy to treat progressive disease and there is no cure. Data from patients with MS, post-mortem histological analysis, and animal models of demyelinating disease have elucidated patterns of MS pathogenesis and underlying mechanisms of neurodegeneration. MRI and molecular biomarkers have been proposed to identify predictors of neurodegeneration and risk factors for disease progression. Early signs of axonal dysfunction have come to light including impaired mitochondrial trafficking, structural axonal changes, and synaptic alterations. With sustained inflammation as well as impaired remyelination, axons succumb to degeneration contributing to CNS atrophy and worsening of disease. These studies highlight the role of chronic demyelination in the CNS in perpetuating axonal loss, and the difficulty in promoting remyelination and repair amidst persistent inflammatory insult. Regenerative and neuroprotective strategies are essential to overcome this barrier, with early intervention being critical to rescue axonal integrity and function. The clinical and basic research studies discussed in this review have set the stage for identifying key propagators of neurodegeneration in MS, leading the way for neuroprotective therapeutic development. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology.

A case of primary optic pathway demyelination caused by oncocytic oligodendrogliopathy of unknown origin

We report the case of a 22-year-old woman presenting with an acute onset of dizziness, gait dysbalance and blurred vision. Magnetic resonance imaging included 3 Tesla and 7 Tesla imaging and revealed a T2-hyperintense, T1-hypointense, non-contrast-enhancing lesion strictly confined to the white matter affecting the right optic radiation. An extensive ophthalmologic examination yielded mild quadrantanopia but no signs of optic neuropathy. The lesion was biopsied. The neuropathological evaluation revealed a demyelinating lesion with marked tissue vacuolization and granular myelin disintegration accompanied by mild T cell infiltration and a notable absence of myelin uptake by macrophages. Oligodendrocytes were strikingly enlarged, displaying oncocytic characteristics and showed cytoplasmic accumulation of mitochondria, which had mildly abnormal morphology on electron microscopy. The diagnosis of multiple sclerosis was excluded. Harding's disease, a variant of Leber's hereditary optic neuropathy, was then suspected. However, neither PCR for relevant mutations nor whole exome sequencing yielded known pathogenetic mutations in the patient's genome. We present a pattern of demyelinating tissue injury of unknown etiology with an oncocytic change of oligodendrocytes and a lack of adequate phagocytic response by macrophages, which to the best of our knowledge, has not been described before.

Diagnosis and classification of optic neuritis

There is no consensus regarding the classification of optic neuritis, and precise diagnostic criteria are not available. This reality means that the diagnosis of disorders that have optic neuritis as the first manifestation can be challenging. Accurate diagnosis of optic neuritis at presentation can facilitate the timely treatment of individuals with multiple sclerosis, neuromyelitis optica spectrum disorder, or myelin oligodendrocyte glycoprotein antibody-associated disease. Epidemiological data show that, cumulatively, optic neuritis is most frequently caused by many conditions other than multiple sclerosis. Worldwide, the cause and management of optic neuritis varies with geographical location, treatment availability, and ethnic background. We have developed diagnostic criteria for optic neuritis and a classification of optic neuritis subgroups. Our diagnostic criteria are based on clinical features that permit a diagnosis of possible optic neuritis; further paraclinical tests, utilising brain, orbital, and retinal imaging, together with antibody and other protein biomarker data, can lead to a diagnosis of definite optic neuritis. Paraclinical tests can also be applied retrospectively on stored samples and historical brain or retinal scans, which will be useful for future validation studies. Our criteria have the potential to reduce the risk of misdiagnosis, provide information on optic neuritis disease course that can guide future treatment trial design, and enable physicians to judge the likelihood of a need for long-term pharmacological management, which might differ according to optic neuritis subgroups.

A Scoping Review on Body Fluid Biomarkers for Prognosis and Disease Activity in Patients with Multiple Sclerosis

Multiple sclerosis (MS) is a complex demyelinating disease of the central nervous system, presenting with different clinical forms, including clinically isolated syndrome (CIS), which is a first clinical episode suggestive of demyelination. Several molecules have been proposed as prognostic biomarkers in MS. We aimed to perform a scoping review of the potential use of prognostic biomarkers in MS clinical practice. We searched MEDLINE up to 25 November 2021 for review articles assessing body fluid biomarkers for prognostic purposes, including any type of biomarkers, cell types and tissues. Original articles were obtained to confirm and detail the data reported by the review authors. We evaluated the reliability of the biomarkers based on the sample size used by various studies. Fifty-two review articles were included. We identified 110 molecules proposed as prognostic biomarkers. Only six studies had an adequate sample size to explore the risk of conversion from CIS to MS. These confirm the role of oligoclonal bands, immunoglobulin free light chain and chitinase CHI3L1 in CSF and of serum vitamin D in the prediction of conversion from CIS to clinically definite MS. Other prognostic markers are not yet explored in adequately powered samples. Serum and CSF levels of neurofilaments represent a promising biomarker.

Mono/polyclonal free light chains as challenging biomarkers for immunological abnormalities

Free light chain (FLC) kappa (k) and lambda (λ) consist of low molecular weight proteins produced in excess during immunoglobulin synthesis and secreted into the circulation. In patients with normal renal function, over 99% of FLCs are filtered and reabsorbed. Thus, the presence of FLCs in the serum is directly related to plasma cell activity and the balance between production and renal clearance. FLCs are bioactive molecules that may exist as monoclonal (m) and polyclonal (p) FLCs. These have been detected in several body fluids and may be key indicators of ongoing damage and/or illness. International guidelines now recommend mFLC for screening, diagnosis and monitoring multiple myeloma and other plasma cell dyscrasias. In current clinical practice, FLCs in urine indicate cast nephropathy and other renal injury, whereas their presence in cerebrospinal fluid is important for identifying central nervous system inflammatory diseases such as multiple sclerosis. Increased pFLCs have also been detected in various conditions characterized by B cell activation, i.e., chronic inflammation, autoimmune disease and HCV infection. Monitoring the coronavirus (COVID-19) pandemic by analysis of salivary FLCs presents a significant opportunity in clinical immunology worthy of scientific pursuit.

Inter-Laboratory Concordance of Cerebrospinal Fluid and Serum Kappa Free Light Chain Measurements

The kappa index (K-Index), calculated by dividing the cerebrospinal fluid (CSF)/serum kappa free light chain (KFLC) ratio by the CSF/serum albumin ratio, is gaining increasing interest as a marker of intrathecal immunoglobulin synthesis. However, data on inter-laboratory agreement of these measures is lacking. The aim was to assess the concordance of CSF and serum KFLC measurements, and of K-index values, across different laboratories. KFLC and albumin of 15 paired CSF and serum samples were analyzed by eight participating laboratories. Four centers used Binding Site instruments and assays (B), three used Siemens instruments and assays (S), and one center used a Siemens instrument with a Binding Site assay (mixed). Absolute individual agreement was calculated using a two-way mixed effects intraclass correlation coefficient (ICC). Cohen's kappa coefficient (k) was used to measure agreement on positive (≥5.8) K-index values. There was an excellent agreement in CSF KFLC measurements across all laboratories (ICC (95% confidence interval): 0.93 (0.87-0.97)) and of serum KFLC across B and S laboratories (ICC: 0.91 (0.73-0.97)), while ICC decreased (to 0.81 (0.53-0.93)) when including the mixed laboratory in the analysis. Concordance for a positive K-Index was substantial across all laboratories (k = 0.77) and within S laboratories (k = 0.71), and very good (k = 0.89) within B laboratories, meaning that patients rarely get discordant results on K-index positivity notwithstanding the testing in different laboratories and the use of different platforms/assays.

Kappa Free Light Chains in Cerebrospinal Fluid in Inflammatory and Non-Inflammatory Neurological Diseases

Background: Oligoclonal bands represent intrathecal immunoglobulin G (IgG) synthesis and play an important role in the diagnosis of multiple sclerosis (MS). Kappa free light chains (KFLC) are increasingly recognized as an additional biomarker for intrathecal Ig synthesis. However, there are limited data on KFLC in neurological diseases other than MS. Methods: This study, conducted at two centers, retrospectively enrolled 346 non-MS patients. A total of 182 patients were diagnosed with non-inflammatory and 84 with inflammatory neurological diseases other than MS. A further 80 patients were classified as symptomatic controls. Intrathecal KFLC production was determined using different approaches: KFLC index, Reiber’s diagram, Presslauer’s exponential curve, and Senel’s linear curve. Results: Matching results of oligoclonal bands and KFLC (Reiber’s diagram) were frequently observed (93%). The Reiber’s diagram for KFLC detected intrathecal KFLC synthesis in an additional 7% of the patient samples investigated (4% non-inflammatory; 3% inflammatory), which was not found by oligoclonal band detection. Conclusions: The determination of both biomarkers (KFLC and oligoclonal bands) is recommended for routine diagnosis and differentiation of non-inflammatory and inflammatory neurological diseases. Due to the high sensitivity and physiological considerations, the assessment of KFLC in the Reiber’s diagram should be preferred to other evaluation methods.

Oligoclonal Bands in Multiple System Atrophy: Case Report and Proposed Mechanisms of Immunogenicity

Multiple System Atrophy (MSA) is a neurodegenerative disease with heterogeneous manifestations and is therefore difficult to diagnose definitively. Because of this, oftentimes an extensive workup for mimickers is undertaken. We herein report a case where the history and cerebrospinal fluid (CSF) findings of oligoclonal bands suggested an inflammatory disorder. Immunomodulatory therapy failed to ameliorate symptoms or alter the trajectory of continued physical decline, prompting re-visitation of the diagnosis. Oligoclonal bands, while generally viewed as specific to multiple sclerosis or other inflammatory conditions, may be seen in other disease processes. Therefore, this finding should not exclude consideration of neurodegenerative disease.

Clinical and Cerebrospinal Fluid Characteristics in 55 Cases of Tolosa-Hunt Syndrome: A Retrospective Analytical Study

BACKGROUND

Several case series of patients with Tolosa-Hunt syndrome have been described in the literature; however, few studies have focused on the cerebrospinal fluid (CSF) characteristics. This study aimed to analyse the CSF characteristics of patients with Tolosa-Hunt syndrome.

METHODS

Fifty-five patients who fulfilled the 3rd Edition of the International Classification of Headache Disorders diagnostic criteria for Tolosa-Hunt syndrome were included in this study. We retrospectively analysed data on CSF parameters, imaging findings, and clinical characteristics of these patients.

RESULTS

Oligoclonal bands (OBs) were detected in the CSF of 13 (13/44, 29.5%) patients. The sex ratio was balanced. The mean age at onset of Tolosa-Hunt syndrome was 46.9 ± 10.23 (range 22-72) years. Eight (8/13, 61.5%) patients had multiple cranial nerve palsies. Lesions limited to the cavernous sinus were found on magnetic resonance imaging in 7 (7/13, 53.8%) patients. OBs were significantly detected more frequently in patients whose samples were evaluated less than 30 days after the onset of this diseases (p = 0.026); however, there were no significant differences in the protein level (p = 0.360) and IgG synthesis rate (p = 0.614).

CONCLUSIONS

The detection of OBs in the CSF of patients with Tolosa-Hunt syndrome was not rare. It would be interesting to follow-up patients with OBs to determine whether they eventually developed an otherwise more specific inflammatory diagnosis.

Molecular biomarkers in multiple sclerosis

Multiple sclerosis (MS) is a highly heterogenous disease regarding radiological, pathological, and clinical characteristics and therapeutic response, including both the efficacy and safety profile of treatments. Accordingly, there is a high demand for biomarkers that sensitively and specifically apprehend the distinctive aspects of the MS heterogeneity, and that can aid in better understanding of the disease diagnosis, prognosis, prediction of the treatment response, and, finally, in the development of new treatments. Currently, clinical characteristics (e.g., relapse rate and disease progression) and magnetic resonance imaging play the most important role in the clinical classification of MS and assessment of its course. Molecular biomarkers (e.g., immunoglobulin G (IgG) oligoclonal bands, IgG index, anti-aquaporin-4 antibodies, neutralizing antibodies against interferon-beta and natalizumab, anti-varicella zoster virus and anti-John Cunningham (JC) virus antibodies) complement these markers excellently. This review provides an overview of exploratory, validated and clinically useful molecular biomarkers in MS which are used for prediction, diagnosis, disease activity and treatment response.

The contribute of cerebrospinal fluid free light-chain assay in the diagnosis of multiple sclerosis and other neurological diseases in an Italian multicenter study

BACKGROUND

Cerebrospinal fluid (CSF) free light chains (FLCs) can be an alternative assay to oligoclonal bands (OCBs) in inflammatory neurological disorders, but threshold has no consensus.

OBJECTIVE

To assess the diagnostic accuracy of CSF FLCs in multiple sclerosis (MS) and other neurological diseases.

METHODS

A total of 406 patients from five Italian centers. FLCs were measured in CSF and serum using Freelite MX assays on Optilite.

RESULTS

A total of 171 patients were diagnosed as MS, 154 non-inflammatory neurological diseases, 48 inflammatory central nervous system (CNS) diseases, and 33 peripheral neurological diseases. Both kFLC and λFLC indices were significantly higher in patients with MS compared to other groups (p < 0.0001). The kFLC index ⩾ 6.4 is comparable to OCB for MS diagnosis (area under the receiver operating characteristic curve (AUC) = 0.876; sensitivity 83.6% vs 84.2%; specificity 88.5% vs 90.6%). λFLC index ⩾ 5 showed an AUC of 0.616, sensitivity of 33.3% and specificity of 90.6%. In all, 12/27 (44.4%) MS patients with negative OCB had kFLC index ⩾ 6.4. Interestingly, 37.5% of 24 patients with a single CSF IgG band showed high kFLC index and 12.5% positive λFLC index.

CONCLUSION

Our findings support the diagnostic utility of FLC indices in MS and other CNS inflammatory disorders, suggesting a combined use of FLC and OCB to help clinicians with complementary information.

Acute autoimmune transverse myelitis following COVID-19 vaccination: A case report

RATIONALE

Transverse myelitis is an infectious or noninfectious inflammatory spinal cord syndrome. We report a rare case of transverse myelitis following vaccination against COVID-19.

PATIENT CONCERNS

A 70-year-old male presented with progressive sensorimotor dysfunction of the bilateral lower limbs 7 days after receiving the mRNA-1273 vaccine against COVID-19. Spinal magnetic resonance imaging revealed intramedullary lesions with gadolinium enhancement on the Th1/2 and Th5/6 vertebral levels. Cerebrospinal fluid (CSF) testing showed a mildly increased level of total protein and positive oligoclonal bands (OCB).

DIAGNOSIS

The patient was diagnosed with acute transverse myelitis.

INTERVENTION

The patient received 5 days of intravenous methylprednisolone pulse (1000 mg/day) followed by oral prednisolone (30 mg/day with gradual tapering).

OUTCOMES

The patient fully recovered from muscle weakness of the lower limbs. He was discharged from our hospital and able to independently walk without unsteadiness.

LESSON

This is a rare case of transverse myelitis following COVID-19 vaccination. Positive OCB in CSF in the present case highlights the possibility of autoimmune processes, including polyclonal activation of B lymphocytes, following vaccination.

Predicting Aggressive Multiple Sclerosis With Intrathecal IgM Synthesis Among Patients With a Clinically Isolated Syndrome

Objective

To determine the best method to measure intrathecal immunoglobulin (Ig) M synthesis (ITMS), a biomarker of worse prognosis in multiple sclerosis (MS). We compared the ability for predicting a poor evolution of 4 methods assessing ITMS (IgM oligoclonal bands [OCMBs], lipid-specific OCMBs [LS-OCMBs], Reibergram, and IgM index) in patients with a clinically isolated syndrome (CIS).

Methods

Prospective study with consecutive patients performed at a referral MS center. We used unadjusted and multivariate Cox regressions for predicting a second relapse, Expanded Disability Status Scale (EDSS) scores of 4 and 6, and development of secondary progressive MS (SPMS).

Results

A total of 193 patients were included, with a median (interquartile range) age of 31 (25–38) years and a median follow-up of 12.9 years. Among all methods, only OCMB, LS-OCMB, and Reibergram significantly identified patients at risk of some of the pre-established outcomes, being LS-OCMB the technique with the strongest associations. Adjusted hazard ratio (aHR) of LS-OCMB for predicting a second relapse was 2.50 (95% CI 1.72–3.64, p < 0.001). The risk of reaching EDSS scores of 4 and 6 and SPMS was significantly higher among patients with LS-OCMB (aHR 2.96, 95% CI 1.54–5.71, p = 0.001; aHR 4.96, 95% CI 2.22–11.07, p < 0.001; and aHR 2.31, 95% CI 1.08–4.93, p = 0.03, respectively).

Conclusions

ITMS predicts an aggressive MS at disease onset, especially when detected as LS-OCMB.

Classification of Evidence

This study provides Class II evidence that lipid-specific IgM oligoclonal bands can predict progression from CIS to MS and a worse disease course over a follow-up of at least 2 years.

New Insights into Multiple Sclerosis Mechanisms: Lipids on the Track to Control Inflammation and Neurodegeneration

Multiple sclerosis (MS) is a central nervous system disease with complex pathogenesis, including two main processes: immune-mediated inflammatory demyelination and progressive degeneration with axonal loss. Despite recent progress in our understanding and management of MS, availability of sensitive and specific biomarkers for these both processes, as well as neuroprotective therapeutic options targeted at progressive phase of disease, are still being sought. Given their abundance in the myelin sheath, lipids are believed to play a central role in underlying immunopathogenesis in MS and seem to be a promising subject of investigation in this field. On the basis of our previous research and a review of the literature, we discuss the current understanding of lipid-related mechanisms involved in active relapse, remission, and progression of MS. These insights highlight potential usefulness of lipid markers in prediction or monitoring the course of MS, particularly in its progressive stage, still insufficiently addressed. Furthermore, they raise hope for new, effective, and stage-specific treatment options, involving lipids as targets or carriers of therapeutic agents.

B Cells in Neuroinflammation: New Perspectives and Mechanistic Insights

In recent years, the role of B cells in neurological disorders has substantially expanded our perspectives on mechanisms of neuroinflammation. The success of B cell-depleting therapies in patients with CNS diseases such as neuromyelitis optica and multiple sclerosis has highlighted the importance of neuroimmune crosstalk in inflammatory processes. While B cells are essential for the adaptive immune system and antibody production, they are also major contributors of pro- and anti-inflammatory cytokine responses in a number of inflammatory diseases. B cells can contribute to neurological diseases through peripheral immune mechanisms, including production of cytokines and antibodies, or through CNS mechanisms following compartmentalization. Emerging evidence suggests that aberrant pro- or anti-inflammatory B cell populations contribute to neurological processes, including glial activation, which has been implicated in the pathogenesis of several neurodegenerative diseases. In this review, we summarize recent findings on B cell involvement in neuroinflammatory diseases and discuss evidence to support pathogenic immunomodulatory functions of B cells in neurological disorders, highlighting the importance of B cell-directed therapies.