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

PLoS One. 2020 Jun 12;15(6):e0234519. doi: 10.1371/journal.pone.0234519. eCollection 2020.

Abstract

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.

MeSH terms

  • Alzheimer Disease / blood
  • Alzheimer Disease / pathology
  • Amyloid beta-Peptides / blood*
  • Axons / metabolism
  • Axons / pathology
  • Biomarkers / blood*
  • Cognitive Dysfunction / blood
  • Cognitive Dysfunction / genetics
  • Cognitive Dysfunction / pathology
  • Female
  • Humans
  • Immunomagnetic Separation
  • Intermediate Filaments / genetics
  • Intermediate Filaments / pathology
  • Male
  • Middle Aged
  • Neurofilament Proteins / blood*
  • Parkinson Disease / blood
  • Parkinson Disease / genetics
  • Parkinson Disease / pathology
  • tau Proteins / blood*

Substances

  • Amyloid beta-Peptides
  • Biomarkers
  • Neurofilament Proteins
  • tau Proteins

Grants and funding

MagQu Co., Ltd provided funding for this study in the form of salaries for Huei-Chun Liu, Chin-Yi Lin and Shieh-Yueh Yang. MagQu Co., Ltd did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘Author contributions’ section.