High level of agreement in a fixed vs. live cell-based assay for antibodies to myelin oligodendrocyte glycoprotein in a real-world clinical laboratory setting.

Introduction: As recognition of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease becomes more widespread, the importance of appropriately ordering and interpreting diagnostic testing for this antibody increases. Several assays are commercially available for MOG testing, and based on a few small studies with very few discrepant results, some have suggested that live cell-based assays (CBA) are superior to fixed CBA for clinical MOG antibody testing. We aimed to determine the real-world agreement between a fixed and live CBA for MOG using two of the most commonly available commercial testing platforms.

Aquaporin-4 Autoantibody Detection by ELISA: A Retrospective Characterization of a Commonly Used Assay.

Objective: Aquaporin-4 (AQP4) serum autoantibodies are detected by a variety of methods. The highest sensitivity is achieved with cell-based assays, but the enzyme-linked immunosorbent assay (ELISA) is still commonly utilized by clinicians worldwide.

Methods: We performed a retrospective review to identify all patients at the University of Utah who had AQP4 ELISA testing at ARUP Laboratories from 2010 to 2017.

Performance evaluation of a radioimmunoprecipitation assay for the detection of N-type voltage-gated calcium channel antibodies.

Background: In this study, we assessed the performance characteristics of a laboratory-developed radioimmunoassay (RIA) to detect N-type voltage-gated calcium channel (N-VGCC) antibodies found in several autoimmune neurologic diseases.

Methods: Four hundred and forty-five (n = 445) sera were evaluated, including 156 sera (50 positive and 106 negative for N-VGCC antibodies) previously tested at Mayo Clinic Laboratories (MCL) and 289 controls (n = 187 disease and n = 102 healthy). Specimens were analyzed with the RIA using N-VGCC labeled with I-ω-conotoxin GVIA.

Autoantibody diversity in paraneoplastic syndromes and related disorders: The need for a more guided screening approach.

Background: Significant progress has been made in understanding the role and diversity of autoantibodies in the pathogenesis, diagnosis and management of paraneoplastic syndrome (PNS) and related autoimmune neurologic diseases. We evaluated the positivity rates for diverse autoantibody panels to rationalize testing strategies and utilization.

Methods: The result patterns for different autoantibody panels for PNS offered at 2 reference laboratories in the U.

Detection of Acetylcholine Receptor Blocking Antibodies by Flow Cytometry.

Objectives: Detection of acetylcholine receptor (AChR) blocking antibodies through the use of a radiolabel has become standard procedure in most laboratories. Known drawbacks associated with radioassay, including cost of radioisotopes, hazards to laboratory professionals, and manufacture and disposal of radioactive materials, have prompted investigation into replacement assays. We describe here a high-throughput immunofluorescent flow cytometric assay designed for the detection of AChR blocking antibodies.

Detection of acetylcholine receptor modulating antibodies by flow cytometry.

Objectives: To determine the clinical utility and performance characteristics of a laboratory-adapted flow cytometric method for the detection of acetylcholine receptor (AChR) modulating antibodies in myasthenia gravis (MG).

Methods: Serum samples from 120 healthy donors and 100 patients with suspected MG were assessed for the ability to reduce surface AChR concentrations (antigenic modulation) in RD (TE671) or DB40 human muscle cell lines by flow cytometry. Reference ranges were established by receiver operating characteristic curve analysis, and results were then compared with those of the current radioimmunoassay (RIA).

Anti-NMDA-receptor antibody encephalitis: performance evaluation and laboratory experience with the anti-NMDA-receptor IgG assay.

Background: Antibodies targeting the NR1 subunit of the N-methyl-d-aspartate-receptor (NMDAR) are considered diagnostic for a novel form of autoimmune encephalitis. We report the validation of a qualitative indirect immunofluorescence antibody (IFA) test for the detection of anti-NMDAR IgG and describe the attributes of antibody-positive patients.

Methods: The anti-NMDAR IgG assay (Euroimmun Diagnosika, Lübeck, Germany) was validated with serum and cerebrospinal fluid (CSF) specimens from 30 healthy and 50 disease controls as well as 5 anti-NMDAR IgG-positive individuals.

Glucocorticoid regulation of lactate dehydrogenase-elevating virus replication in macrophages.

Lactate dehydrogenase-elevating virus (LDV) is a macrophage-tropic arterivirus which generally causes a persistent viremic infection in mice. LDV replication in vivo seems to be primarily regulated by the extent and dynamics of a virus-permissive macrophage population. Previous studies have shown that glucocorticoid treatment of chronically LDV-infected mice transiently increases viremia 10-100-fold, apparently by increasing the productive infection of macrophages.

Serum total homocysteine increases with the rapid proliferation rate of tumor cells and decline upon cell death: a potential new tumor marker.

Background: We were interested to know why cancer patients are frequently associated with elevated circulating total homocysteine (tHcy) even though they are not treated with anti-folate drugs.

Methods: We employed tissue cultures to compare both the homocysteine (Hcy)-released and production of tumor markers between tumor and normal cell lines.

Results: We detected much higher concentrations of homocysteine (Hcy) released by the tumor cells.