Reference Center for Biological Markers of Dementia (BIODEM), Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; Current affiliation: Fujirebio Europe, Ghent, Belgium;
Reference Center for Biological Markers of Dementia (BIODEM), Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; Department of Neurology and Memory Clinic, Hospital Network Antwerp, Antwerp, Belgium; Department of Neurology and Alzheimer Research Center, University Medical Center Groningen, Groningen, The Netherlands.
Clin Chem. 2015 May;61(5):734-43. doi: 10.1373/clinchem.2014.236679. Epub 2015 Apr 13.
Analyses of cerebrospinal fluid (CSF) biomarkers (β-amyloid protein, total tau protein, and hyperphosphorylated tau protein) are part of the diagnostic criteria of Alzheimer disease. Different preanalytical sample procedures contribute to variability of CSF biomarker concentrations, hampering between-laboratory comparisons. The aim of this study was to explore the influence of fractionated sampling, centrifugation, freezing temperature, freezing delay, and freeze-thaw cycles on CSF biomarker analyses.
We studied fractionated sampling in sequential aliquots of lumbar CSF. Centrifuged and noncentrifuged samples from the same fraction were compared. CSF samples were subjected to different protocols (liquid nitrogen, -80 °C, and -20 °C; 24 h at 2-8 °C; and 24 and 48 h at room temperature). To study the influence of freeze-thaw cycles, samples were thawed up to 4 times and refrozen at -80 °C. CSF was collected in polypropylene tubes. We measured CSF biomarker concentrations with commercially available single-analyte Innotest assays.
CSF biomarker concentrations from non-blood-contaminated samples are not influenced by centrifugation or fractionated sampling. Freezing temperature and delayed storage can affect biomarker concentrations; freezing of CSF samples at -80 °C as soon as possible after collection is recommended. Consecutive freezing and thawing of CSF samples up to 3 times had little effect.
Temperature of freezing, delay until freezing, and freeze-thaw cycles significantly influence CSF biomarker concentrations, stressing the need for standard operating procedures for preanalytical sample handling. The differences observed in this study are, however, relatively small, and the impact on the clinical value of these CSF biomarkers needs to be determined.
脑脊液（CSF）生物标志物（β-淀粉样蛋白、总tau 蛋白和磷酸化 tau 蛋白）分析是阿尔茨海默病诊断标准的一部分。不同的样本前处理程序会导致 CSF 生物标志物浓度的变化，从而阻碍了实验室之间的比较。本研究旨在探讨分段采样、离心、冷冻温度、冷冻延迟和冻融循环对 CSF 生物标志物分析的影响。
我们研究了腰椎 CSF 的分段采样。比较了同一部分离心和未离心的样本。CSF 样本采用不同的方案（液氮、-80°C 和-20°C；2-8°C 下 24 小时；室温下 24 和 48 小时）。为了研究冻融循环的影响，样本被解冻了 4 次并在-80°C 下重新冷冻。CSF 收集在聚丙烯管中。我们使用市售的单分析物 Innotest 测定法测量 CSF 生物标志物浓度。
未受血液污染的样本的 CSF 生物标志物浓度不受离心或分段采样的影响。冷冻温度和储存延迟会影响生物标志物浓度；建议尽快在收集后将 CSF 样本在-80°C 下冷冻。CSF 样本连续冷冻和解冻多达 3 次，影响较小。
冷冻温度、延迟冷冻时间和冻融循环显著影响 CSF 生物标志物浓度，这强调了需要为样本前处理制定标准操作程序。然而，在本研究中观察到的差异相对较小，这些 CSF 生物标志物的临床价值需要进一步确定。
