Amyloid β1-40 quantification in CSF:: Comparison between chromatographic and immunochemical methods

Background/Aims: Amyloid beta (A beta) is the principal component of senile plaques, one of the hallmarks of Alzheimer's disease (AD). Evidence is accumulating that soluble aggregates (oligomers) of A beta are important in the pathogenesis of AD. Methods: We compared three different methods for quantification of the 40 amino acid form of A beta (A beta(40)) in CSF, two based on antibodies [ELISA and surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF) with antibody-coated arrays] and one based on direct binding of proteins to a protein array [SELDI-TOF and immobilized metal affinity [copper] (IMAC30)]. Results: CSF A beta(40) concentration was only found to be significantly elevated in AD (127% of control levels; p = 0.0095) using SELDI-TOF with IMAC30 arrays. Conclusions: These data suggest that the measured A beta level in CSF may differ depending on whether antibody-based methods are used or not, possibly caused by epitope masking due to A beta oligomerization or to binding of A beta to carrier proteins. Copyright (C) 2007 S. Karger AG, Basel.