Development of an assay of plasma neurofilament light chain utilizing immunomagnetic reduction technology

• Published in: PloS one Vol. 15; no. 6; p. e0234519
• Main Authors: Liu, Huei-Chun, Lin, Wei-Che, Chiu, Ming-Jang, Lu, Cheng-Hsien, Lin, Chin-Yi, Yang, Shieh-Yueh
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 12.06.2020; Public Library of Science (PLoS)
• Subjects: Alzheimer Disease - blood; Alzheimer Disease - pathology; Alzheimer's disease; Amyloid beta-Peptides - blood; Antibodies; Assaying; Axons - metabolism; Axons - pathology; Biology and Life Sciences; Biomarkers; Biomarkers - blood; Cerebrospinal fluid; Chains; Cognitive Dysfunction - blood; Cognitive Dysfunction - genetics; Cognitive Dysfunction - pathology; Creutzfeldt-Jakob disease; Cytoplasmic filaments; Dementia; Dementia disorders; Diagnostic reagents; Differential diagnosis; Dynamic range; Engineering and Technology; Female; Health aspects; Hospitals; Humans; Immunomagnetic Separation; Intermediate Filaments - genetics; Intermediate Filaments - pathology; Laboratories; Levels; Magnetic properties; Male; Medicine and Health Sciences; Middle Aged; Movement disorders; Nanoparticles; Neurodegenerative diseases; Neurofilament Proteins - blood; Parkinson Disease - blood; Parkinson Disease - genetics; Parkinson Disease - pathology; Parkinson's disease; Patients; Physiological aspects; Plasma; Reduction; Research and Analysis Methods; Sensitivity; tau Proteins - blood; Technology; Technology utilization; Taiwan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0234519

Axonal damage leads to the release of neurofilament light chain (NFL), which enters the CSF or blood. In this work, an assay kit for plasma NFL utilizing immunomagnetic reduction (IMR) was developed. Antibodies against NFL were immobilized on magnetic nanoparticles to develop an IMR NFL kit. The preclinical properties, such as the standard curve, limit of detection (LoD), and dynamic range, were characterized. Thirty-one normal controls (NC), fifty-two patients with Parkinson's disease (PD) or PD dementia (PDD) and thirty-one patients with Alzheimer's disease (AD) were enrolled in the study evaluating the plasma NFL assay using an IMR kit. T-tests and receiver operating characteristic (ROC) curve analysis were performed to investigate the capability for discrimination among the clinical groups according to plasma NFL levels. The LoD of the NFL assay using the IMR kit was found to be 0.18 fg/ml. The dynamic range of the NFL assay reached 1000 pg/ml. The NC group showed a plasma NFL level of 7.70 ± 4.00 pg/ml, which is significantly lower than that of the PD/PDD (15.85 ± 7.82 pg/ml, p < 0.001) and AD (19.24 ± 8.99 pg/ml, p < 0.001) groups. A significant difference in plasma NFL levels was determined between the PD and AD groups (p < 0.01). Through ROC curve analysis, the cut-off value of the plasma NFL concentration for differentiating NCs from dementia patients (AD and PD/PDD) was found to be 12.71 pg/ml, with a clinical sensitivity and specificity of 73.5% and 90.3%, respectively. The AUC was 0.868. Furthermore, the cut-off value of the plasma NFL concentration for discriminating AD from PD/PDD was found to be 18.02 pg/ml, with a clinical sensitivity and specificity of 61.3% and 65.4%, respectively. The AUC was 0.630. An ultrasensitive assay for measuring plasma NFL utilizing IMR technology was developed. Clear differences in plasma NFL concentrations were observed among NCs and PD and AD patients. These results imply that the determination of plasma NFL is promising not only for screening dementia but also for differential diagnosis.