Amyloid-beta 42 adsorption following serial tube transfer.
BACKGROUND
Cerebrospinal fluid (CSF) amyloid-beta 38 (Aβ38), 40 (Aβ40), 42 (Aβ42) and total tau (T-tau) are finding increasing utility as biomarkers of Alzheimer's disease (AD). The purpose of this study was to determine whether measured CSF biomarker concentrations were affected by transfer of CSF between tubes, and whether addition of a non-ionic surfactant mitigates any observed effects.


METHODS
AD and control CSF was transferred consecutively between polypropylene tubes. Aβ peptides and T-tau were measured with and without addition of Tween 20 (0.05%).


RESULTS
Measured concentrations of Aβ42 decreased by approximately 25% with each consecutive transfer. Measured concentrations of Aβ38 and Aβ40 were also observed to decrease significantly with each consecutive transfer (approximately 16% loss per transfer). Measured concentrations of T-tau also decreased significantly, but at much smaller magnitude than the Aβ peptides (approximately 4% loss per transfer). The addition of Tween 20 mitigated this effect in all samples.


CONCLUSIONS
Consecutive CSF transfer between tubes has a significant impact on the measured concentration of all Aβ peptides, and significant effect of lesser magnitude on T-tau. This would be sufficient to alter biomarker ratios enough to mislead diagnosis. The introduction of Tween 20 at the initial aliquoting stage was observed to significantly mitigate this effect.
Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London, UK.
Jamie
J
Toombs
Dementia Research Centre, Department of Neurodegeneration, Institute of Neurology, University College London, Queen Square, London, UK.
Ross W
RW
Paterson
Dementia Research Centre, Department of Neurodegeneration, Institute of Neurology, University College London, Queen Square, London, UK.
Jonathan M
JM
Schott
Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London, UK ; Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
Henrik
H
Zetterberg