Validation of the LUMIPULSE automated immunoassay for the measurement of core AD biomarkers in cerebrospinal fluid

Abstract

Objectives The core cerebrospinal fluid (CSF) biomarkers; total tau (tTau), phospho-tau (pTau), amyloid β 1-42 (Aβ 1-42), and the Aβ 1-42/Aβ 1-40 ratio have transformed Alzheimer’s disease (AD) research and are today increasingly used in clinical routine laboratories as diagnostic tools. Fully automated immunoassay instruments with ready-to-use assay kits and calibrators has simplified their analysis and improved reproducibility of measurements. We evaluated the analytical performance of the fully automated immunoassay instrument LUMIPULSE G (Fujirebio) for measurement of the four core AD CSF biomarkers and determined cutpoints for AD diagnosis. Methods Comparison of the LUMIPULSE G assays was performed with the established INNOTEST ELISAs (Fujirebio) for hTau Ag, pTau 181, β-amyloid 1-42, and with V-PLEX Plus Aβ Peptide Panel 1 (6E10) (Meso Scale Discovery) for Aβ 1-42/Aβ 1-40, as well as with a LC-MS reference method for Aβ 1-42. Intra- and inter-laboratory reproducibility was evaluated for all assays. Clinical cutpoints for Aβ 1-42, tTau, and pTau was determined by analysis of three cohorts of clinically diagnosed patients, comprising 651 CSF samples. For the Aβ 1-42/Aβ 1-40 ratio, the cutpoint was determined by mixture model analysis of 2,782 CSF samples. Results The LUMIPULSE G assays showed strong correlation to all other immunoassays (r>0.93 for all assays). The repeatability (intra-laboratory) CVs ranged between 2.0 and 5.6%, with the highest variation observed for β-amyloid 1-40. The reproducibility (inter-laboratory) CVs ranged between 2.1 and 6.5%, with the highest variation observed for β-amyloid 1-42. The clinical cutpoints for AD were determined to be 409 ng/L for total tau, 50.2 ng/L for pTau 181, 526 ng/L for β-amyloid 1-42, and 0.072 for the Aβ 1-42/Aβ 1-40 ratio. Conclusions Our results suggest that the LUMIPULSE G assays for the CSF AD biomarkers are fit for purpose in clinical laboratory practice. Further, they corroborate earlier presented reference limits for the biomarkers.

Amyloid processing in COVID‐19‐associated neurological syndromes

“…Patients not meeting both of these criteria were excluded. These COVID‐19 neurological cases were compared to neurologically healthy controls, which were derived from the healthy aging study from individuals who are amyloid and tau PET‐negative (non‐COVID controls) as previously reported (ethics approval IUSMD 16–60) (Gobom et al, 2021; Paterson et al, 2021). All cerebrospinal fluid (CSF) samples were collected in polypropylene tubes and spun, aliquoted, and frozen within 24 hours, alongside samples collected as part of standard clinical care with written informed consent.…”

“…Alzheimer's disease, amyloid processing, APP, beta amyloid, COVID-19 reported (ethics approval IUSMD 16-60) (Gobom et al, 2021;Paterson et al, 2021). All cerebrospinal fluid (CSF) samples were collected in polypropylene tubes and spun, aliquoted, and frozen within 24 hours, alongside samples collected as part of standard clinical care with written informed consent.…”

Differential proteomic profile of lumbar and ventricular cerebrospinal fluid

“…The CSF samples were analyzed at the Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden. CSF concentrations of Aβ40, Aβ42, total tau (T-tau) and phosphorylated tau (P-tau) were measured with Lumipulse technology (Fujirebio, Ghent, Belgium), as previously described [34]. CSF neuro lament light (NfL) concentration was measured using an in-house enzyme-linked immunosorbent assay as previously described [35].…”

Differences between blood and cerebrospinal fluid glial fibrillary Acidic protein levels: The effect of sample stability

“…CSF Aβ42 and Aβ40 concentrations were measured as a part of clinical routine using the commercial fully automated LUMIPULSE G1200 (Fujirebio). Aβ positivity in these individuals was defined as CSF Aβ42/Aβ40 ratio <0.072 14 . After collection, polypropylene tubes containing 500 uL of serum and CSF were snap frozen on dry ice (15 min) and thawed (30 min).…”