Determination of Positivity Cutoff for an Automated Aspergillus fumigatus-Specific Immunoglobulin-G Assay in a National Reference Laboratory.

Background: Detection of serum-specific immunoglobulin G (sIgG) to Aspergillus fumigatus traditionally relied on precipitin assays, which lack standardization and have poor analytical sensitivity. Automated quantitative immunoassays are now more widely used alternatives. A challenge, however, is determining reference interval (RI) cutoffs indicative of disease presence.

Comparison of three methods for the detection of antibodies against muscle-specific kinase.

Objectives: To compare 3 different methods for the detection of antibodies against muscle-specific kinase (MuSK).

Methods: MuSK antibody testing was performed in 237 serum samples by enzyme-linked immunosorbent assay (ELISA) and fixed cell-based assay (f-CBA-IFA). One hundred and forty-eight (148) of the sera had previously been tested by RIA during clinical testing: 47 MuSK antibody positive and 101 MuSK antibody negative.

Evaluation of a Novel Multiplex Platform for Simultaneous Detection of IgG Antibodies Against the 4 Main SARS-CoV-2 Antigens.

Background: Numerous serology assays are available for detection of SARS-CoV-2 antibodies but are limited in that only 1 or 2 target antigen(s) can be tested at a time. Here, we describe a novel multiplex assay that simultaneously detects and quantifies IgG antibodies to SARS-CoV-2 antigens, spike (S), nucleocapsid (N), receptor-binding domain (RBD), and N-terminal domain (NTD) in a single well.

Methods: Sensitivity was determined using samples (n = 124) from confirmed SARS-CoV-2 RT-PCR positive individuals.

Establishing age-stratified red blood cell fatty acid reference ranges using model-based clustering and iterative application of the harris-boyd method.

Background: The current assessment of nutritional status and diagnosis of essential fatty acids deficiency (EFAD) utilizes the analysis of long-chain fatty acids (LCFAs) in serum or plasma; however, these concentrations do not represent habitual LCFA intake. LCFAs in red blood cells (RBCs) are less prone to intra-individual variability and exclude the need for fasting, which is unrealistic in pediatric populations. Our study objective was to characterize the RBC LCFA profiles in pediatric and adult reference populations and establish age-specific reference intervals (RIs).

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.

Evaluation of a Surrogate Enzyme-Linked Immunosorbent Assay-Based Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) cPass Neutralization Antibody Detection Assay and Correlation With Immunoglobulin G Commercial Serology Assays.

Context.—: Emerging evidence shows correlation between the presence of neutralization antibodies (nAbs) and protective immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently available commercial serology assays lack the ability to specifically identify nAbs.

Evaluation of 3 SARS-CoV-2 IgG Antibody Assays and Correlation with Neutralizing Antibodies.

Background: As serologic assays for SARS-CoV-2 become more widely utilized, it is important to understand their performance characteristics and correlation with neutralizing antibodies. We evaluated 3 commonly used SARS-CoV-2 IgG assays (Abbott, DiaSorin, and EUROIMMUN) for clinical sensitivity, specificity, and correlation with neutralizing antibodies, and then compared antibody kinetics during the acute phase of infection.

Methods: Three panels of samples were tested on every assay.

Histone methyltransferase Smyd1 regulates mitochondrial energetics in the heart.

Smyd1, a muscle-specific histone methyltransferase, has established roles in skeletal and cardiac muscle development, but its role in the adult heart remains poorly understood. Our prior work demonstrated that cardiac-specific deletion of Smyd1 in adult mice (Smyd1-KO) leads to hypertrophy and heart failure. Here we show that down-regulation of mitochondrial energetics is an early event in these Smyd1-KO mice preceding the onset of structural abnormalities.

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).