Detection of intrathecal IgG antibody for varicella and measles diagnosis by evaluation and comparison of a commercial IgG chemiluminescent immunoassay with two ELISAs.

OBJECTIVES: Analyse alternative methods of intrathecal antibody detection by comparing chemiluminescent immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) techniques to determine if CLIA can replace ELISA in the diagnosis of CNS infections. METHODS: A panel of 280 paired samples-cerebrospinal fluid (CSF) and serum-with known antibody reactivities (Varicella, n = 60; Measles, n = 120) and negative samples (n = 100) were used to evaluate the performance of six serological test kits (Enzygnost, VirClia®, and Serion ELISA (Measles and Variella). RESULTS: For Measles virus IgG, the VirClia® IgG monotest revealed 97% and 94% positive and negative agreement to the Enzygnost as reference test, respectively. In contrast, Serion ELISA kits yielded values of 18% and 90%. For the Varicella Zoster virus (VZV) IgG, the VirClia® IgG monotest showed 97% and 90% positive and negative agreement compared to Enzygnost. The Serion ELISA kits showed values of 55% and 86%, respectively. ROC analysis revealed that the areas under the curve for Measles and VZV IgGs were 0.7 and 0.852, respectively, using the Serion kit, and 0.963 and 0.955, for Vircell S.L CLIA technique. VirClia® monotest values were calculated using an antibody index cut-off of 1.3. CONCLUSION: The findings indicate that CLIA testing can improve antibody detection in CSF samples, aiding the diagnosis of infectious neurological impairments.

Validation of ELISA assays for the calculation of FLC indices for the diagnosis of intrathecal immunoglobulin synthesis.

OBJECTIVES: Define the cutoff thresholds of the Kappa (K) and Lambda (L) free light chains (FLC) indices for the detection of intrathecal immunoglobulin synthesis (IIS) using the new K and L FLC ELISA from SEBIA. The reference technique, which is not readily standardized between laboratories, is based on the demonstration of oligoclonal banding (OCB) in cerebrospinal fluid (CSF) which is absent in serum. For the past 6 years, we have also routinely calculated the K FLC index using The Binding Site (TBS) reagents on an Optilite instrument, an approach increasingly used as an alternative and/or a complement to electrophoretic analysis. METHODS: We analyzed 391 serum/CSF pairs divided into three groups. The first group were cases without OCB and with normal albumin CSF/serum ratio (n=174). The second group were cases with specific OCB (n=73). The last group included patients with increased albumin CSF/sera ratio without OCB (n=142). RESULTS: Analysis of the first group determined that the cutoffs for detection of IIS are respectively 2.55 and 1.02 for the K FLC and L FLC indices. Of the 73 cases with IIS, only 2 had a K FLC index below this threshold (sensitivity of 97.26%), while 16 out of 73 cases (78.08%) and 13 out of 72 cases (81.94%) had an IgG and L FLC index below the cutoffs, respectively. Additionally, we illustrate equivalent performances for prediction of the presence of OCB between SEBIA and TBS methods. CONCLUSIONS: Sebia K FLC and L FLC assays are adequate alternative methods for the diagnosis of IIS.

Cerebrospinal Fluid Features in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Reverse Transcription Polymerase Chain Reaction (RT-PCR) Positive Patients.

This study analyzed the cerebrospinal fluid features of 31 coronavirus disease 2019 (COVID-19) patients with neurological complications. We observed neither severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the cerebrospinal fluid, nor intrathecal immunoglobulin G (IgG) synthesis but did observe signs of blood-brain barrier disruption. These results might serve as a basis for a better understanding of SARS-CoV-2 related neuropathogenesis.

Free light chains in the cerebrospinal fluid. Comparison of different methods to determine intrathecal synthesis.

Background Free light chains (FLC) have been proposed as diagnostic biomarkers in the cerebrospinal fluid (CSF) of patients with inflammatory central nervous system (CNS) diseases. However, which method to use for determining an intrathecal FLC synthesis has not yet been clarified. The objective of this study was to compare the diagnostic performance of CSF FLC concentration, FLC quotient (QFLC), FLC index and FLC intrathecal fraction (FLCIF). Methods κ- and λ-FLC were measured by nephelometry under blinded conditions in CSF and serum sample pairs of patients with clinically isolated syndrome (CIS; n = 60), multiple sclerosis (MS; n = 60) and other neurological diseases (n = 60) from four different MS centers. QFLC was calculated as the ratio of CSF/serum FLC concentration, the FLC index as QFLC/albumin quotient and the percentage FLCIF by comparing QFLC to a previously empirically determined, albumin quotient-dependent reference limit. Results CSF FLC concentration, QFLC, FLC index and FLCIF of both the κ- and λ-isotype were significantly higher in patients with CIS and MS than in the control group, as well as in oligoclonal bands (OCB) positive than in OCB negative patients. Each parameter was able to identify MS/CIS patients and OCB positivity, however, diagnostic performance determined by receiver operating characteristic (ROC) analyses differed and revealed superiority of FLC index and FLCIF. Conclusions These findings support the diagnostic value of FLC measures that correct for serum FLC levels and albumin quotient, i.e. blood-CSF barrier function.

Diagnostic value of specific antibody synthesis in brain of patients with neuroinfections

Introduction: Viral encephalitis accounts for 40-70% of all cases worldwide, central nervous system infections pose a diagnostic challenge because clinical manifestations are not typically pathognomonic for specific pathogens, and a wide range of agents can be causative. The aim: To assess the diagnostic value of intrathecal synthesis of specific antibodies in patients with inflammatory lesions of the central nervous system. Material and methods: Within the framework of the study, two groups of 90 people in each were formed from the patients with neuroinfections admitted to our Center. Intrathecal synthesis (ITS) of total (unspecific) IgG in members of one of group (group of compare) was determined. Brain synthesis of specific antibodies (Ab) to some neurotropic pathogens (herpes simplex virus 1/2, cytomegalovirus, Epstein-Barr virus, varicella zoster virus, rubella virus, Borrelies) was studied in the second group of patients (group of interest). There were no statistically significant differences between groups by gender and age. Encephalitis and encephalomyelitis prevailed among patients of both groups. Results: ITS of total IgG was established in 30 (33.3 ± 6.1 %) patients of the first group with IgG index more than 0.6 indicating on inflammatory process in CNS and no marked changes of CSF. ITS of specific Ab was determined in 23 of 90 (25.6 ± 4.6 %) patients included into group of interest. In more than half of cases Ab to several infectious agents were detected simultaneously. ITS of various specificity, in particular, to measles and rubella viruses, and VZV, known as MRZ-reaction, is characteristic of some autoimmune lesions of CNS, multiple sclerosis first of all. In fact, further research of 5 patients with MRZ-reaction confirmed their autoimmune failure of CNS. Detection of ITS in the CSF samples didn't depend on concentration of specific Ab in serum and CSF and wasn't followed by HEB dysfunctions which were observed with the same frequency in patients with or without ITS (13.0 % and 13.6 % respectively). Conclusions: Specific Ab synthesis to several neurotropic pathogens in the CSF of significant part of examined patients was established. Thus, diagnostic value of ITS of specific immunoglobulins seems to be limited to cases in which autoimmune damage of the CNS is suspected.

Application of κ free light chains in cerebrospinal fluid as a biomarker in multiple sclerosis diagnosis: development of a diagnosis algorithm.

BACKGROUND: The determination of κ free light chains (KFLC) in cerebrospinal fluid (CSF) by nephelometry is a feasible alternative to immunoglobulin G oligoclonal bands (OCB) in the evaluation of intrathecal synthesis of immunoglobulin in multiple sclerosis (MS) and other demyelinating diseases. The aim of this study was to assess the diagnostic value of KFLC and its inclusion in a procedure algorithm along with OCB interpretation. METHODS: A cross-sectional study, which included 123 patients with a CSF OCB request, was carried out. Isoelectric focusing followed by immunofixation was used to detect OCB, and nephelometry was used to analyze KFLC. The KFLC index was calculated using CSF/serum quotient of KFLC and albumin. The KFLC index was compared with MS diagnosis to find the optimal cutoff. It was obtained from the receiver operating characteristic (ROC) curves and the Youden method. RESULTS: The CSF KFLC median was 1.66 mg/L in the MS group, whereas in other central nervous system diseases, KFLC showed generally no or only moderate increase in CSF (median 0.10 mg/L). KFLC index showed a significant difference between groups. ROC analysis for CSF KFLC concentration, and KFLC indexes were 91.88% and 93.94%, respectively. The best cutoff for the KFLC index was 2.91 for MS diagnosis (sensitivity: 83.78%; specificity: 85.88%). The proposed algorithm showed high sensitivity (89.19%) and specificity (84.71%). CONCLUSIONS: KFLC determination is rapid and automatized, but it has no higher sensitivity and specificity than OCB in MS diagnosis. Nevertheless, when used in screening, it could reduce the number of manual OCB tests.

Cerebrospinal fluid free light chains as diagnostic biomarker in neuroborreliosis.

BACKGROUND: Free light chains (FLC) have been proposed as diagnostic biomarker in patients with inflammatory central nervous system diseases. The objective of this study was to investigate the diagnostic utility of intrathecal κ- and λ-FLC synthesis in patients with neuroborreliosis. METHODS: κ- and λ-FLC were measured by nephelometry under blinded conditions in cerebrospinal fluid (CSF) and serum sample pairs of 34 patients with neuroborreliosis and compared to a cohort of 420 control patients. κ-FLC index was calculated as [CSF κ-FLC/serum κ-FLC]/[CSF albumin/serum albumin], and λ-FLC index in analogy. RESULTS: κ-FLC and λ-FLC index were significantly elevated in patients with neuroborreliosis compared to the control group. At a specificity level of 95%, κ-FLC and λ-FLC index showed a diagnostic sensitivity of 88.2% and 100%. In comparison, IgM and IgG synthesis according to Reiber formula, IgG index >0.7 and OCB status reached a sensitivity of 83.9%, 44.1%, 58.8% and 64.7%. CONCLUSION: These findings support the diagnostic value of intrathecal FLC synthesis in neuroborreliosis patients and demonstrate a valid, easy and rater-independent alternative for the detection of an intrathecal immunoglobulin production.

Quantitation of intrathecal immunoglobulin synthesis - a new empirical formula.

BACKGROUND AND PURPOSE: Intrathecal immunoglobulin (Ig) synthesis occurs in various chronic inflammatory neurological diseases. Different formulae have been developed for quantitative determination of Ig synthesis within the cerebrospinal fluid (CSF) compartment. The hyperbolic formula of Reiber is frequently used which, however, returns a considerable number of false positive results in empirical observations. METHODS: A computerized database of more than 19 000 paired CSF and serum samples was screened for patients presumed negative for local Ig synthesis and a new formula characterizing this collective was calculated. The validity of this formula was confirmed by several validation steps. RESULTS: A cohort of 1173 patients with normal CSF findings was used for quantile regression. The 97.5th quantile of the formula Qlim(IgX)=a×Qalbb was considered as the cut-off curve for intrathecal Ig synthesis using different constants a and b for IgG, IgA and IgM. Compared to the Reiber formula, a lower level of false positive results was produced especially for IgM and IgA which was confirmed in a separate clinically well defined validation cohort. In 77 patients with discrepant findings between Reiber and our formula no specific diagnoses were found confirming the low diagnostic value of borderline Ig synthesis. CONCLUSIONS: A new approximation formula was developed for determination of intrathecal Ig synthesis which produces fewer false positive results without reducing diagnostic sensitivity.

An observational study of inflammation in the central nervous system in patients with bipolar disorder.

OBJECTIVES: The potential influence of infections and immunological changes on the aetiology and pathogenesis of bipolar disorder (BD) has been discussed. Our aim was to detect intrathecal specific antibody synthesis against the neurotropic infectious agents that have previously been linked to BD. METHODS: Paired cerebrospinal fluid (CSF) and serum samples from 40 patients with BD were analysed using the enzyme-linked immunosorbent assay to detect the concentration of antibodies against the following neurotropic infectious pathogens: Toxoplasma gondii (T. gondii), herpes simplex virus (HSV) types 1 and 2, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). The specific antibody index (AI) was calculated, and an AI > 1.4 was considered to be evidence of intrathecal specific antibody synthesis. Twenty-six patients with pseudotumour cerebri served as controls. RESULTS: Eight out of 40 patients with BD displayed specific intrathecal antibody synthesis against at least one of the tested neurotropic agents compared to only one patient in the control group (p = 0.061, not significant). Of these eight patients with BD, no significant prevalence of any particular neurotropic pathogen was evident. Five out of 40 patients with BD showed oligoclonal bands in the CSF, suggestive of a chronic immune reaction in the central nervous system (CNS). CONCLUSIONS: We found evidence for increased production of antibody in the CSF of individuals with BD. However, the trend for polyspecific intrathecal antibody synthesis, as well as the presence of oligoclonal bands, might indicate activation of the intrathecal humoral immune system in a subgroup of patients with BD, as it is known to be associated with autoimmune disorders of the CNS.

[Meningeal tertiary lymphoid organs: Major actors in intrathecal autoimmunity]. / Organes lymphoïdes tertiaires méningés : des acteurs majeurs de l'auto-immunité intrathécale.

Multiple sclerosis (MS) is characterized by an intrathecal synthesis of immunoglobulins synthesized by B-cell clones and by a brain infiltrate of clonal T-cells. The clonal maturation of these lymphocytes takes place in tertiary lymphoid organs (TLO) developed in the intrathecal compartment. TLO are acquired lymphoid organs able to develop in the vicinity of the inflammatory sites, where they mount a complete antigen-driven immune response. We here review TLO pathophysiology in animal models of MS and human MS. Several pieces of evidence suggest that intrathecal TLO may play a major role in the clinical impairment. Potential therapeutic applications are examined.

Characteristics of patients consulted for suspected Lyme neuroborreliosis in an endemic area.

INTRODUCTION: Some patients with unexplained neurological symptoms sought care for presumed Lyme neuroborreliosis (LNB). We aimed to compare patients' characteristics with and without LNB. MATERIAL AND METHODS: All patients consulting for LNB suspicion and having a lumbar puncture between 2014 and 2020 in a high endemic area of Lyme borreliosis were included in the study. RESULTS: One hundred fifty-five patients were included. Forty-five patients (29 %) had LNB (mean age: 57.6 years, 28.9 % of women) including 17 with isolated intrathecal synthesis. One hundred and ten patients had no LNB (mainly neurological (29 %) and rheumatological diseases (19 %)). Non-neurological symptoms were similar in patients with LNB and patients with no LNB (asthenia, 31 % vs. 46 %, p = 0.14, arthralgia 20 % vs. 31 %, p = 0.14) with the exception of myalgia, which was less frequent in patients with LNB (4.4 % vs. 19.1 % p = 0.02). In multivariable analysis, factors associated with LNB were presence of facial nerve palsy (OR = 5.7), radiculopathy (OR = 11.3), positive Lyme serology (OR = 5.4) and duration of symptoms less than 3 months (OR = 4.48). Patients with isolated intrathecal synthesis had a longer duration of symptoms (3 vs 1 months) than patients with pleocytosis. Asthenia (5.9 % vs. 32.1 %), headaches (0 % vs. 39.3 %) neuropathic pain (17.6 % vs. 50 %) and facial palsy (11.8 % vs. 39.3 %) were less frequent in patients with isolated intrathecal synthesis than patients with pleocytosis. The presence of isolated subjective neurological symptoms (paresthesia, memory disorders, insomnia, irritability, asthenia, headaches) was reported in 7/17 (41 %) of patients with isolated intrathecal synthesis, 2/28 (7.1 %) in patients with pleocytosis and 75/110 (68 %) in patients without LNB (p < 0.001). CONCLUSION: More than one quarter of patients consulted for suspected LNB had non-neurologic symptoms, whether or not they have a LNB. Concerning patients with isolated intrathecal synthesis, the question of presence of sequelae with a spontaneously cured disease or an active Lyme borreliosis requiring antibiotic remain.

HLA dependency and possible clinical relevance of intrathecally synthesized anti-IgLON5 IgG4 in anti-IgLON5 disease.

Background: Anti-IgLON5 disease is a rare chronic autoimmune disorder characterized by IgLON5 autoantibodies predominantly of the IgG4 subclass. Distinct pathogenic effects were described for anti-IgLON5 IgG1 and IgG4, however, with uncertain clinical relevance. Methods: IgLON5-specific IgG1-4 levels were measured in 46 sera and 20 cerebrospinal fluid (CSF) samples from 13 HLA-subtyped anti-IgLON5 disease patients (six females, seven males) using flow cytometry. Intervals between two consecutive serum or CSF samplings (31 and 10 intervals, respectively) were categorized with regard to the immunomodulatory treatment active at the end of the interval, changes of anti-IgLON5 IgG1 and IgG4 levels, and disease severity. Intrathecal anti-IgLON5 IgG4 synthesis (IS) was assessed using a quantitative method. Results: The median age at onset was 66 years (range: 54-75), disease duration 10 years (range: 15-156 months), and follow-up 25 months (range: 0-83). IgLON5-specific IgG4 predominance was observed in 38 of 46 (83%) serum and 11 of 20 (55%) CSF samples. Anti-IgLON5 IgG4 levels prior clinical improvement in CSF but not serum were significantly lower than in those prior stable/progressive disease. Compared to IgLON5 IgG4 levels in serum, CSF levels in HLA-DRB1*10:01 carriers were significantly higher than in non-carriers. Indeed, IgLON5-specific IgG4 IS was demonstrated not only in four of five HLA-DRB1*10:01 carriers but also in one non-carrier. Immunotherapy was associated with decreased anti-IgGLON5 IgG serum levels. In CSF, lower anti-IgLON5 IgG was associated with immunosuppressive treatments used in combination, that is, corticosteroids and/or azathioprine plus intravenous immunoglobulins or rituximab. Conclusion: Our findings might indicate that CSF IgLON5-specific IgG4 is frequently produced intrathecally, especially in HLA-DRB1*10:01 carriers. Intrathecally produced IgG4 may be clinically relevant. While many immunotherapies reduce serum IgLON5 IgG levels, more intense immunotherapies induce clinical improvement and may be able to target intrathecally produced anti-IgLON5 IgG. Further studies need to confirm whether anti-IgLON5 IgG4 IS is a suitable prognostic and predictive biomarker in anti-IgLON5 disease.

Improving the efficiency of free kappa light chains as diagnostic biomarker of Multiple Sclerosis by using a novel algorithm.

BACKGROUND: Intrathecal immunoglobulin synthesis (ITS) plays a crucial role in the diagnosis of multiple sclerosis (MS). Traditionally, the gold standard method for detecting ITS has been through the analysis of oligoclonal bands (OCB). However, the paradigm has shifted with the introduction of the free kappa light chains (FKLC) method. In fact, a recent consensus recommends evaluating FKLC index (FKLCi) as the primary approach and reserving oligoclonal bands with borderline results. The objective of our study is to investigate the diagnostic efficiency of combining FKLC with other methods to predict ITS while minimizing the reliance on OCB. METHODS: A total of 192 patients were included in the study, consisting of 145 individuals diagnosed with multiple sclerosis (pwMS) and 46 with other neurological diseases (controls). Among the MS cases, 100 patients were assigned to the Training Cohort (TC), while an external Validation Cohort (VC) comprised of 45 MS patients was established. Diagnostic efficiency was assessed for FKLCi, OCB, Link index, and the Reiber formula for IgG and FKLC. Optimal cutoff values for Link index and FKLCi were also determined. The last procedure was developed for diverse algorithms using the parameters mentioned above, which included the optimal cutoffs previously obtained. The calculations were conducted independently for both the TC and the VC, as well as for a composite cohort formed by combining data from all patients (OC) RESULTS: One algorithm, named KRO, was developed based on the determination of FKLCi and Reiber Formula as the primary diagnostic parameters. For cases where the FKLCi result was mildly increased, OCB was utilized as a supplementary test. The KRO algorithm demonstrated superior diagnostic accuracy in the OC (89%), resulting in a reduction of OCB consumption by 91%. DISCUSSION: The KRO algorithm demonstrated superior sensitivity and accuracy although lower specificity and NPV compared to the use of FKLCi and OCB alone. The present research aligns with the new consensus recommendations regarding the diagnostic approach. Our findings indicate that employing a combined marker approach via KRO could prove to be a proficient screening tool for multiple sclerosis. This approach also holds the potential to address inherent limitations associated with each individual marker. However, to further validate and solidify the efficacy of our algorithm, additional studies involving larger cohorts are warranted.

Application of oligoclonal bands and other cerebrospinal fluid variables in multiple sclerosis and other neuroimmunological diseases: a narrative review.

Background and Objective: As an essential but not specific marker of multiple sclerosis, oligoclonal bands are bands displayed by electrophoretic separation technique. Detection method evolves from conventional protein electrophoresis to isoelectric focusing electrophoresis. This article aims to review the role of oligoclonal bands in the diagnosis of multiple sclerosis and other neuroimmunological diseases. Methods: The search engine PubMed (https://www.ncbi.nlm.nih.gov/pmc/) was used to research the keywords: "blood brain barrier", "blood brain barrier permeability", "detection methods", "multiple sclerosis" and "oligoclonal bands". A narrative review was conducted to literature findings from 1937 to 2021. Key Content and Findings: We first introduced the history of oligoclonal bands and its detection techniques. Next, the interpretation of different results of oligoclonal bands and the clinical implication, especially the value for the diagnosis of multiple sclerosis were discussed. Then the different prevalence of oligoclonal bands in multiple sclerosis between eastern and western countries and its occurrence rate in other neuroimmunological diseases were reviewed. Finally, we discussed the detection methods of blood brain barrier permeability and intrathecal immunoglobulin synthesis. It reveals that comprehensive analysis of oligoclonal bands, blood-brain barrier permeability and intrathecal synthesis of immunoglobulin provides valuable supporting information for the diagnosis of multiple sclerosis and other neuroimmunological diseases. Conclusions: This review discusses the comprehensive application of oligoclonal bands in multiple sclerosis and other neuroimmunological diseases.

Cerebrospinal Fluid CXCL13 as Candidate Biomarker of Intrathecal Immune Activation, IgG Synthesis and Neurocognitive Impairment in People with HIV.

Plasma C-X-C-motif chemokine ligand-13 (CXCL13) has been linked to disease progression and mortality in people living with HIV (PLWH) and is a candidate target for immune-based strategies for HIV cure. Its role in central nervous system (CNS) of PLWH has not been detailed. We described CSF CXCL13 levels and its potential associations with neurological outcomes. Cross-sectional study enrolling PLWH without confounding for CXCL13 production. Subjects were divided according to CSF HIV-RNA in undetectable (< 20 cp/mL) and viremics. CSF CXCL13, and biomarkers of blood-brain barrier (BBB) impairment, intrathecal synthesis, and immune activation were measured by commercial immunoturbidimetric and ELISA assays. All subjects underwent neurocognitive assessment. Sensitivity analyses were conducted in subjects with intact BBB only. 175 participants were included. Detectable CSF CXCL13 was more common in the viremic (31.4%) compared to the undetectable group (13.5%; OR 2.9 [1.4-6.3], p = 0.006), but median levels did not change (15.8 [8.2-91.0] vs 10.0 [8.1-14.2] pg/mL). In viremics (n = 86), CXCL13 associated with higher CSF HIV-RNA, proteins, neopterin, intrathecal synthesis and BBB permeability. In undetectable participants (n = 89), CXCL13 associated with higher CD4+T-cells count, CD4/CD8 ratio, CSF proteins, neopterin, and intrathecal synthesis. The presence of CXCL13 in the CSF of undetectable participants was associated with increased odds of HIV-associated neurocognitive disorders (58.3% vs 28.6%, p = 0.041). Sensitivity analyses confirmed all these findings. CXCL13 is detectable in the CSF of PLWH that show increased intrathecal IgG synthesis and immune activation. In PLWH with CSF viral suppression, CXCL13 was also associated with neurocognitive impairment.

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.

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.

Anti-TBE Intrathecal Synthesis as a Prediction Marker in TBE Patients.

Tick-borne encephalitis (TBE) is an emerging vector-borne disease in Europe caused by tick-borne encephalitis virus (TBEV), which belongs to Flaviviridae. Although most of the patients quickly recover from TBE, some require further neurological and psychiatric treatment due to persistent symptoms. The aim of the study was to evaluate the usefulness of an antibodies index for predicting the course of the disease and potential persistent sequalae. Sixty-six patients (49 males and 17 females, mean age 45.97 ± 13.69 years) with TBE hospitalized in the Department of Infectious Diseases and Neuroinfections, Medical University of Bialystok, Poland, in years 2016-2019 were included to the study. TBE antibodies titer in serum and CSF samples were measured with an Anti-TBEV ELISA (IgM, IgG) EUROIMMUN test. Patients who developed persistent sequelae after TBE had significantly lower IgG intrathecal index at admission. Additionally, IgG2/IgG1was significantly higher in patients who developed sequelae. IgG intrathecal index might be a useful tool for the prediction of TBE sequelae development.

Intrathecal immunoglobin synthesis and its role in patients with neurosyphilis.

Background: Intrathecal protein synthesis (ITS) occurs in various central nervous system disorders, but few quantitative studies have focused on ITS for neurosyphilis (NS) in southwestern China. We made a study to quantitatively assess the ITS in patients with NS and to investigate the association between ITS and the stages of NS. Methods: CSF-serum specimen pairs from 142 patients (66 NS and 76 non-NS/syphilis) were collected for routine CSF and serum tests. The NS group was divided into slight and severe subgroups according to the NS stages. Three formulas for the quantitative determination of the intrathecal synthesis were calculated to characterize the specimens, including the Ig index (QIg/Qalb), Ig extended index (Ig_EI), and intrathecally synthesized fraction (IgIF) using the hyperbolic function. The role of QTPPA/QIgG as an antibody index (AI = Q specific Ig/QIgG) was also explored. Results: Sero_TRUST titres (1:16, 1:1-1:256), sero_TPPA titres (1:163840, 1:1280-1:1310720), total protein (MTP), and CSF_Igs (p < 0.05) were found to be significantly elevated in the NS group. Intrathecal Ig synthesis can be identified using all three formulas in the NS group. The pattern of Ig intrathecal synthesis was IgIF-G (48.62%) > IgIF-A = IgIF-M (p < 0.05), with the dominant intrathecal fraction being IgG (median, 48.62%), which was also verified by QIgG> Qalb> QIgM = QIgA. In the slight NS group, the intrathecal fractions of IgM (>0 in 4 out of 20 cases) and IgG (>0 in 16 out of 20) were lower than the intrathecal fractions of IgM (>0 in 19 out of 35 cases) and IgG (>0 in 33 out of 38) in the severe group (p < 0.05). The area under the curve (AUC) of the CSF_TPPA antibody index was 0.867 (0.792, 0.922), with an optimal cutoff point of 0.81, providing a sensitivity of 88.91% and specificity of 84.62%. Conclusion: Although the intrathecal synthesis pattern is IgG dominant in patients with NS, brain-derived IgM and IgA can also be found. Moreover, intrathecal IgM and IgG were associated with a parenchymatous type of neurosyphilis. Syphilis-specific antibodies are a new potential tool for NS diagnosis.

Intrathecal Synthesis Index of Specific Anti-Treponema IgG: a New Tool for the Diagnosis of Neurosyphilis.

Neurosyphilis (NS) diagnosis is challenging because clinical signs are diverse and unspecific, and a sensitive and specific laboratory test is lacking. We tested the performance of an antibody index (AI) for intrathecal synthesis of specific anti-Treponema IgG by enzyme-linked immunosorbent assay (ELISA) for NS diagnosis. We conducted a retroprospective monocentric study including adults with neurological symptoms who had serum and cerebral spinal fluid (CSF) samples collected between 2006 and 2021. Two NS definitions were used. NS1 included patients with neurological symptoms, positive Treponema pallidum particle agglutination (TPPA) serology, and CSF-TPPA of ≥320, as well as CSF-leukocytes of >5 cells/mm3 and/or CSF-protein of >0.45 g/L and/or a reactive CSF-VDRL/RPR test. NS2 included patients with acute ocular and/or otologic symptoms, positive TPPA serology, and a response to NS treatment. Controls were patients with central nervous system disorders other than neurosyphilis. Anti-Treponema pallidum IgG were measured simultaneously in serum and CSF, and AI was calculated according to Reiber diagram. We assessed the AI test area under the curve (AUC), sensitivity/specificity, and estimated positive and negative predictive values. In total, 16 NS1 patients, 11 NS2 patients, and 71 controls were included. With an AI of ≥1.7 as a positive test for NS diagnostic, specificity was 98.6% (95% confidence interval [CI 95%] of 92.4 to 100.0) and sensitivity was 81.3% (CI 95% of 54.4 to 96.0) for NS1 and 98.6% (CI 95% 92.4 to 100.0) and 27.3% (CI 95% 6.0 to 61.0), respectively, for NS2. Positive and negative predictive values were >95% for NS1 and >85% for NS2, for prevalence above and below 20%. Measuring an AI for intrathecal synthesis of specific anti-Treponema pallidum IgG is a new promising tool highly specific for NS diagnosis. IMPORTANCE In the context of a lack of a gold standard for the diagnosis of neurosyphilis due to either nonspecific or nonsensitive tests, we present in this article a new promising tool highly specific for NS diagnosis. This new test involves measuring an intrathecal synthesis index of specific anti-Treponema IgG by ELISA.