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Introduction: Myasthenia gravis (MG) is a prototypical autoimmune disease, characterized by pathogenic autoantibodies targeting structures of the neuromuscular junction. Radioimmunoprecipitation assays (RIPAs) represent the gold standard for their detection. However, new methods are emerging to complement, or overcome RIPAs, also with the perspective of eliminating the use of radioactive reagents. Areas covered: We discuss advances in laboratory methods, prompted especially by cell-based assays (CBAs), for the detection of the autoantibodies of MG diagnostics, above all those to the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low molecular-weight receptor-related low-density lipoprotein-4 (LRP4). Expert opinion: CBA technology makes AChRs aggregate on cell membranes, thus allowing to detect autoantibodies to clustered AChRs, with reduction of seronegative MG cases. The diagnostic relevance of RIPA/CBA-measurable LRP4 antibodies is still unclear, in Caucasian patients at least. Live CBAs for the detection of AChR, MuSK, and LRP4 antibodies might represent an alternative to RIPAs, but first require full validation. CBAs could be used as screening tests, limiting RIPAs for antibody quantification. To this end, ELISAs might be an alternative. Fixation procedures preserving enough degree of antigen conformationality could yield AChR and MuSK CBAs suitable for a wide use in clinical-chemistry laboratories [ABSTRACT FROM AUTHOR]

Background: Neuroimmunology has impressively expanded in the past decade. Novel assays, especially cell-based assays (CBAs) can detect conformational antibodies (Abs) recognizing antigens in their native conformation. Generally, the availability of in-house and of commercial tests has improved the diagnostics, but introduced demanding laboratory tasks. Hence, standardization and quality controls represent a key step to promote accuracy. We report on the results of the 2018 external quality assessment program (EQAP) organized by the Italian Neuroimmunology Association. Methods: EQAP regarded 10 schemes, including oligoclonal bands (OCBs), intracellular-neuronal (ICN)-Abs, neuronal-surface (NS)-Abs, aquaporin-4 (AQP4)-Abs, myelin oligodendrocyte glycoprotein (MOG)-Abs, myelin-associated glycoprotein (MAG)-Abs, ganglioside-Abs, acetylcholine-receptor (AChR)-Abs, and muscle-specific-kinase (MuSK)-Abs, and 34 laboratories. Assays were classified as tissue-based assays (TBAs), solid-phase assays (SPAs), liquid-phase assays (LPAs), and CBAs. Thirty-three samples were provided. Results: Three-quarter of the tests were commercial. Median accuracy for the laboratories was 75% (range 50–100). In 8/10 schemes, at least one sample provided discrepant results. Inter-laboratory "substantial agreement" was found in 6/10 schemes (AChR, MuSK, MAG, AQP4, MOG, and NS-Abs), whereas the worst agreements regarded OCBs and ganglioside-Abs. Both commercial and in-house assays performed better in experienced laboratories. Conclusions: Assays could be divided in (a) robust commercial tests with substantial inter-laboratory agreement (MAG-Abs; AChR- and MuSK-Abs); commercial/"in-house" tests with (b) partial inter-laboratory agreement (AQP4-Abs, MOG-Abs, NS-Abs, ICN-Abs), and (c) with large inter-laboratory disagreement (OCBs, ganglioside-Abs). This real-life snapshot of the neuroimmunology test performances highlights shortcomings attributable to technician-dependent performances, assay structural limitations, and errors in test interpretations. [ABSTRACT FROM AUTHOR]

Background: Anti-ganglioside antibodies are currently used in the differential diagnosis of suspected immune-mediated neuropathies. In-house and increasingly used commercial assays seem to perform suboptimally, and comparative information on their analytical performance are essentially lacking. Born within the frame of guidelines and standardization activities by the Italian Association of Neuroimmunology, this external quality assessment scheme (EQAS) is a real-life snapshot of the laboratory diagnostics in this field. Methods: The EQAS consisted of five surplus, anonymized serum samples from patients with clinically-defined neuropathies and two serum samples from healthy blood donors. Eight laboratories used commercial line-/dot-blots, seven in-house/commercial ELISAs (in addition, 13 laboratories tested a recently released ELISA by Bühlmann). Only high anti-ganglioside antibody reactivities were considered, in accordance with consolidated recommendations. Results: Large variations in anti-ganglioside antibody profiles were observed, even, although to a lesser extent, within homogeneous classes of assays. Concordance between the profiles and clinical phenotypes was also partial. Conclusions: Although conducted on a relatively small, but representative number of Italian laboratories, this EQAS shows a critical between-laboratory disagreement in the test results of anti-ganglioside antibodies. Also considering the trend for using certified assays in generalist laboratories, strong efforts toward standardization and the identification of the best method(s) for their determinations are compellingly needed. [ABSTRACT FROM AUTHOR]

Introduction: N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most common autoimmune encephalitis due to autoantibodies against neuronal surface antigens, can affect both children and adults, leading to neurological and neuropsychological sequelae. However, it is potentially treatable and the prompt start of immunotherapy associates with better prognosis. Conversely, misdiagnosis can be harmful. The detection of NMDAR antibodies in serum and cerebrospinal fluid plays a pivotal role in the diagnostic work-up. Reliable methods for NMDAR antibody detection are thus fundamental to assure accurate diagnosis and allow early treatments. Areas covered: This review recapitulates the pathogenic mechanisms of NMDAR encephalitis as a model of antibody mediated synaptopathy, and gives insights into the related state-of-the-art laboratory testing. The differences in clinical presentations, tumor associations and responses to treatments between adults and children are also described. Expert commentary: The relevance of NMDAR encephalitis has placed neuroimmunology laboratories in a crucial position, but methods for NMDAR antibody detection are awaiting thorough and consensus-based standardizations. In the next few years, this process, along with novel insights into the pathogenic mechanisms, could improve the disease management and clarify the still pending role of NMDAR antibodies in healthy people and in other more common neuropsychiatric disorders. [ABSTRACT FROM PUBLISHER]

This document presents the guidelines for anti-myelin-associated glycoprotein (MAG) antibody testing that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of sponsoring Italian Association of Neuroimmunology (AINI) congresses. The main clinical information on anti-MAG antibody polyneuropathy, indications and limits of anti-MAG antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists. [ABSTRACT FROM AUTHOR]

This document presents the guidelines for anti-ganglioside antibody testing that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Main clinical information on dysimmune peripheral neuropathies, indications and limits of anti-ganglioside antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists. [ABSTRACT FROM AUTHOR]

This document presents the guidelines for anti-aquaporin-4 (AQP4) antibody testing that has been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on neuromyelitis optica spectrum disorders, indications and limits of anti-AQP4 antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists. [ABSTRACT FROM AUTHOR]

This document presents the guidelines for the cerebrospinal fluid (CSF) analysis and the determination of oligoclonal bands (OCBs) as pivotal tests in neuroinflammatory pathologies of the central nervous system. The guidelines have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on the pathologies in which the CSF analysis is indicated, and, particularly, on those characterized by the presence of OCBs in the intrathecal compartment, indications and limits of CSF analysis and OCB determination, instructions for result interpretation, and agreed laboratory protocols (Appendix) are reported for the communicative community of neurologists and clinical pathologists. [ABSTRACT FROM AUTHOR]

This document presents the guidelines for onconeural antibody testing that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on paraneoplastic neurological syndromes, indications and limits of onconeural antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists. [ABSTRACT FROM AUTHOR]

This document presents the guidelines for testing antibodies against neuronal surface antigens that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on autoimmune encephalitis associated with antibodies against neuronal surface antigens, indications and limits of testing for such antibodies, instructions for result interpretation, and an agreed laboratory protocol (Appendix A) are reported for the communicative community of neurologists and clinical pathologists. [ABSTRACT FROM AUTHOR]

• MOG Abs are associated with seizures in heterogeneous clinical settings. • Isolated seizures in MOG Ab-positive patients can precede demyelinating events. • Testing for MOG Abs might be considered in children with unexplained seizures. • Evidence of MOG Ab-associated autoimmune epilepsy is circumstantial at present. Myelin oligodendrocyte glycoprotein (MOG) antibodies (Abs) have been associated with a heterogeneous range of acquired CNS demyelinating disorders. More recently, increasing evidence correlates the presence of such Abs with seizures, occurring in concomitance with CNS demyelinating events, or even as isolated phenomena. In this scenario, the full clinical spectrum of MOG Ab-associated seizures and the contribution of such Abs to epileptogenesis are unclear. We report on two paradigmatic cases of MOG Ab-associated seizures, one showing isolated seizures, without evidence of encephalopathy or MRI changes, followed by a demyelinating event one month later, and the other presenting with seizures as the main manifestation of an acute disseminated encephalomyelitis (ADEM) event. To better frame this topic, we performed a literature review, identifying 49 patients with MOG Ab-associated disorders presenting seizures at any stage of their disease, and analysed the clinico-therapeutic, brain MRI, cerebrospinal fluid, and EEG features. MOG Ab-associated seizures occurred mostly during encephalitis, including: a) "cortical encephalitis", a clinically poorly defined syndrome characterised by gray matter lesions on brain MRI, with or without subcortical white matter involvement; b) ADEM; c) NMDAR encephalitis with demyelinating features. Seizures can also occur in isolation, often in clusters of focal motor seizures, in patients with normal brain MRI, heralding the more typical MOG Ab-associated demyelinating syndrome by days to months. Testing for MOG Abs should be considered in children with isolated and unexplained seizures, and in adults with suspected encephalitis and/or seizures. In these cases, MOG Abs detection is highly relevant for patients' clinical management. [ABSTRACT FROM AUTHOR]