title: Both targeted mass spectrometry and flow sorting analysis methods detected the decreased serum apolipoprotein E level in Alzheimer's disease patients.
abstract: Apolipoprotein E (ApoE) polymorphism has been appreciated as a valuable predictor of Alzheimer disease (AD), and the associated ε4 allele has been recognized as an indicator of susceptibility to this disease. However, serum ApoE levels have been a controversial issue in AD, due to the great variability regarding the different target detection methods, ethnicity, and the geographic variations of cohorts. The aim of this study was to validate serum ApoE levels in relation to AD, particularly using two distinct detection methods, liquid chromatography-selected reaction monitoring (SRM) mass spectrometry and microsphere-based fluorescence-activated cell sorting (FACS) analysis, to overcome experimental variations. Also, comparison of serum ApoE levels was performed between the level of protein detection by FACS and peptide level by SRM in both control and AD patients. Results from the two detection methods were cross-confirmed and validated. Both methods produced fairly consistent results, showing a significant decrease of serum ApoE levels in AD patients relative to those of a control cohort (43 control versus 45 AD, p < 0.0001). Significant correlation has been revealed between results from FACS and SRM (p < 0.0001) even though lower serum ApoE concentration values were measured in protein by FACS analysis than in peptide-level detections by SRM. Correlation study suggested that a decrease of the serum ApoE level in AD is related to the mini-mental state exam score in both results from different experimental methods, but it failed to show consistent correlation with age, gender, or clinical dementia rating.
authors: Department of Biochemistry and Biomedical Sciences, Seoul National University, College of Medicine, 28 Yungun-dong, Jongro-gu, Seoul 110-799, Korea;
authors: Sun-Ho
authors: SH
authors: Han
authors: Jun Seok
authors: JS
authors: Kim
authors: Youngju
authors: Y
authors: Lee
authors: Heesun
authors: H
authors: Choi
authors: Jong-Won
authors: JW
authors: Kim
authors: Duk Lyul
authors: DL
authors: Na
authors: Eun Gyeong
authors: EG
authors: Yang
authors: Myeong-Hee
authors: MH
authors: Yu
authors: Daehee
authors: D
authors: Hwang
authors: Cheolju
authors: C
authors: Lee
authors: Inhee
authors: I
authors: Mook-Jung
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood*; D000595:Amino Acid Sequence; D001057:Apolipoproteins E / Q000097:blood*; D001774:Blood Chemical Analysis / Q000379:methods*; D016022:Case-Control Studies; D015536:Down-Regulation; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008863:Microspheres; D008875:Middle Aged; D008969:Molecular Sequence Data; D015203:Reproducibility of Results
chemical_list: D001057:Apolipoproteins E