Details

Autor(en) / Beteiligte

• Klafki, Hans W
• Rieper, Petra
• Matzen, Anja
• Zampar, Silvia
• Wirths, Oliver
• Vogelgsang, Jonathan
• Osterloh, Dirk
• Rohdenburg, Lara
• Oberstein, Timo J
• Jahn, Olaf
• Beyer, Isaak
• Lachmann, Ingolf
• Knölker, Hans-Joachim
• Wiltfang, Jens

Titel

Development and Technical Validation of an Immunoassay for the Detection of APP 669-711 (Aβ -3-40 ) in Biological Samples

Ist Teil von

• International journal of molecular sciences, 2020-09, Vol.21 (18)

Ort / Verlag

Switzerland

Erscheinungsjahr

2020

Quelle

MEDLINE

Beschreibungen/Notizen

• The ratio of amyloid precursor protein (APP) (Aβ )/Aβ in blood plasma was reported to represent a novel Alzheimer's disease biomarker. Here, we describe the characterization of two antibodies against the N-terminus of Aβ and the development and "fit-for-purpose" technical validation of a sandwich immunoassay for the measurement of Aβ . Antibody selectivity was assessed by capillary isoelectric focusing immunoassay, Western blot analysis, and immunohistochemistry. The analytical validation addressed assay range, repeatability, specificity, between-run variability, impact of pre-analytical sample handling procedures, assay interference, and analytical spike recoveries. Blood plasma was analyzed after Aβ immunoprecipitation by a two-step immunoassay procedure. Both monoclonal antibodies detected Aβ with no appreciable cross reactivity with Aβ or N-terminally truncated Aβ variants. However, the amyloid precursor protein was also recognized. The immunoassay showed high selectivity for Aβ with a quantitative assay range of 22 pg/mL-7.5 ng/mL. Acceptable intermediate imprecision of the complete two-step immunoassay was reached after normalization. In a small clinical sample, the measured Aβ /Aβ and Aβ /Aβ ratios were lower in patients with dementia of the Alzheimer's type than in other dementias. In summary, the methodological groundwork for further optimization and future studies addressing the Aβ /Aβ ratio as a novel biomarker candidate for Alzheimer's disease has been set.