Validation of a Commercial Chemiluminescence Immunoassay for the Simultaneous Measurement of Three Different Amyloid-β Peptides in Human Cerebrospinal Fluid and Application to a Clinical Cohort

Article type: Research Article

Authors: Klafki, Hans-W.^{a; 3; *} | Hafermann, Henning^{b; 3} | Bauer, Chris^c | Haussmann, Ute^{b; 1} | Kraus, Inga^{a; d} | Schuchhardt, Johannes^c | Muck, Stephan^{e; 2} | Scherbaum, Norbert^b | Wiltfang, Jens^{a; d}

Affiliations: [a] Department of Psychiatry and Psychotherapy, University Medical Center Goettingen, Georg-August-University, Goettingen, Germany | [b] LVR-Klinikum Essen, Department of Psychiatry and Psychotherapy, Faculty of Medicine, University of Duisburg-Essen, Essen, Germany | [c] MicroDiscovery GmbH, Berlin, Germany | [d] German Center for Neurodegenerative Diseases (DZNE), Research Site Goettingen, Germany | [e] Memory Clinic at the Elisabeth Hospital, Geriatrie-Zentrum Haus Berge, Essen, Germany

Correspondence: [*] Correspondence to: Dr. Hans-W. Klafki, Department of Psychiatry and Psychotherapy, University Medical Center Goettingen, Georg-August-University, Von-Siebold-Str. 5, D-37075Goettingen, Germany. Tel.: +49 0 551 39 20967; E-mail: [email protected].

Note: [1] current address: University of Duisburg-Essen, Essen, Germany.

Note: [2] current address: Evangelisches Krankenhaus Gelsenkirchen, Klinik für Neurologie, Gelsenkirchen, Germany.

Note: [3] These authors contributed equally to this work.

Abstract: A comprehensive assay validation campaign of a commercially available chemiluminescence multiplex immunoassay for the simultaneous measurement of the amyloid-β peptides Aβ38, Aβ40, and Aβ42 in human cerebrospinal fluid (CSF) is presented. The assay quality parameters we addressed included impact of sample dilution, parallelism, lower limits of detection, lower limits of quantification, intra- and inter-assay repeatability, analytical spike recoveries, and between laboratory reproducibility of the measurements. The assay performed well in our hands and fulfilled a number of predefined acceptance criteria. The CSF levels of Aβ40 and Aβ42 determined in a clinical cohort (n = 203) were statistically significantly correlated with available ELISA data of Aβ1–40 (n = 158) and Aβ1–42 (n = 179) from a different laboratory. However, Bland-Altman method comparison indicated systematic differences between the assays. The data presented here furthermore indicate that the CSF concentration of Aβ40 can surrogate total CSF Aβ and support the hypothesis that the Aβ42/Aβ40 ratio outperforms CSF Aβ42 alone as a biomarker for Alzheimer’s disease due to a normalization to total Aβ levels.

Keywords: Alzheimer’s disease, amyloid-β peptide, assay validation, biomarker, cerebrospinal fluid, multiplex immunoassay

DOI: 10.3233/JAD-160398

Journal: Journal of Alzheimer's Disease, vol. 54, no. 2, pp. 691-705, 2016