Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, United States.
Fujirebio Diagnostics Inc., Malvern, PA, United States.
J Appl Lab Med. 2024 Jul 1;9(4):789-802. doi: 10.1093/jalm/jfae033.
Standardizing cerebrospinal fluid (CSF) laboratory protocols will improve the reliability and availability of clinical biomarker testing required for prescription of novel Alzheimer disease (AD) therapies. This study evaluated several preanalytical handling and storage factors common to β-amyloid1-42 (Aβ1-42), β-amyloid1-40 (Aβ1-40), and phosphorylated tau (pTau181) concentrations including storage at different temperatures, extended cap contact, various mixing methods, and multiple freeze-thaw cycles.
Aβ1-42, Aβ1-40, and pTau181 concentrations were measured using LUMIPULSE G1200 automated assays. Samples were collected in polypropylene tubes of various volumes. Sample cap-contact was evaluated by storing samples in upright and inverted positions at either 4°C for 1 week or -80°C for 1 month. To assess mixing methods, samples were freeze-thawed and mixed by inversion, vortex, horizontal roller, or unmixed prior to assay sampling. The impact of successive freeze-thaw cycles was assessed through freezing, thawing, and analyzing CSF samples.
Short-term storage at 4°C did not affect Aβ1-42, Aβ1-40, or pTau181 measurements in any tube type. Tube cap contact affected Aβ1-42 in 2.5 mL tubes and pTau181 levels in 10 mL tubes. No difference was observed between mixing methods. After 4 freeze-thaw cycles, Aβ1-42 significantly decreased but Aβ1-40 remained unchanged. Utilizing the Aβ1-42/Aβ1-40 ratio, Aβ1-42 values normalized, maintaining ratio values within ±5% of baseline measurements.
Storage of CSF at 4°C for 1 week or -80°C for 1 month did not significantly affect Aβ1-42, Aβ1-40, pTau181, or associated ratio measurements. Tube cap-contact impacted pTau181 and pTau181/Aβ1-42 values in larger tubes. Mixing methods are equivalent. The Aβ1-42/Aβ1-40 ratio compensates for freeze-thaw variability up to 4 cycles.
标准化脑脊液（CSF）实验室方案将提高新型阿尔茨海默病（AD）治疗方案所需的临床生物标志物检测的可靠性和可用性。本研究评估了几种常见的β-淀粉样蛋白 1-42（Aβ1-42）、β-淀粉样蛋白 1-40（Aβ1-40）和磷酸化 tau（pTau181）浓度的预分析处理和储存因素，包括在不同温度下储存、延长管帽接触、各种混合方法和多次冻融循环。
使用 LUMIPULSE G1200 自动化检测试剂盒测量 Aβ1-42、Aβ1-40 和 pTau181 浓度。样本收集在不同体积的聚丙烯管中。通过将样本以直立和倒置的方式储存在 4°C 1 周或-80°C 1 个月，评估管帽接触。为了评估混合方法，在进行检测采样之前，将样本进行冻融并通过颠倒、涡旋、水平滚轮或不混合进行混合。通过冷冻、解冻和分析 CSF 样本来评估连续冻融循环的影响。
在任何管类型中，4°C 的短期储存都不会影响 Aβ1-42、Aβ1-40 或 pTau181 的测量。管帽接触会影响 2.5ml 管中的 Aβ1-42 和 10ml 管中的 pTau181 水平。混合方法之间没有差异。经过 4 次冻融循环后，Aβ1-42 显著减少，但 Aβ1-40 保持不变。利用 Aβ1-42/Aβ1-40 比值，Aβ1-42 值得到了标准化，使比值值保持在与基线测量值的±5%以内。
在 4°C 储存 CSF 1 周或-80°C 储存 1 个月不会显著影响 Aβ1-42、Aβ1-40、pTau181 或相关比值的测量。管帽接触会影响较大管中的 pTau181 和 pTau181/Aβ1-42 值。混合方法是等效的。Aβ1-42/Aβ1-40 比值可补偿多达 4 个循环的冻融变化。
