Measurement of plasma amyloid-β precursor protein APP770 concentration in healthy young volunteers: Preliminary study of APP770 as a potential biomarker for Alzheimer's disease diagnosis.

Abstract

Purpose : APP770, expressed in brain endothelial cells, is a different isoform from neuronal APP695. Soluble APP770 (sAPP770) is produced by APP770 cleavage by α-secretase. sAPP770 has been proposed as a candidate biomarker of Alzheimer disease. To investigate sAPP770 levels in human plasma, a new commercially available sandwich ELIZA system has been developed. This study was undertaken to test whether this system would be useful in determining plasma sAPP770 levels. Subjects and Methods : Subjects were 20 healthy young volunteers. Plasma sAPP770 concentration was assayed by sandwich ELIZA using the Human APP770 assay kit. Results: Plasma concentration of sAPP770 in all subjects was 56.80ng/mL. The concentration in male subjects was 44.31ng/mL and in the female subjects was 60.99ng/mL. No significant difference in male and female concentrations was observed. The detection limit of this kit was 0.03ng/mL, and the working range of the assay was 0-6.2 ng/mL. Conclusion : The sandwich ELIZA method tested in this study is a useful protocol to analyze plasma sAPP770 concentrations.