Cytokines are soluble and readily analyzed signaling molecules which reveal vital cues about the state of the immune system. As such, they serve in diagnosis and monitoring of immune-related disorders, where strictly controlled handling of the samples including storage and freeze/thawing procedures are required. In basic research and clinical trials, human serum samples can be left for long-term storage before processing. Storage space is commonly limited in scientific laboratories, which require storage of fewer but larger aliquots of patient serum samples. There are also practical limitations to the number of analytes to be processed at the same time. Further, new findings and technological progress might prompt analysis of hitherto unconsidered or undetectable molecules. Repeated freeze/thawing of serum samples is therefore a likely scenario, raising the question of the stability of the measured analytes under such conditions. To address this question, we subjected serum samples with spiked-in T-helper cell associated cytokines to several cycles of freeze/thawing under different conditions, including storage at -20 °C or -80 °C and thawing at 4 °C, 22 °C, and 37 °C, respectively. The concentration of TNF-α, IL-4, IL-17F, and IL-22 decreased after storage at room temperature for 4 h before freezing. Generally, storage at -20 °C resulted in reduced cytokine concentrations. This contrasts storage at -80 °C, which gave stable analyte concentrations; unaffected by repeated freeze/thaw cycles. The study presented here highlights the need for sentinel samples with known cytokine concentrations as internal control for the freeze/thaw process.

中文翻译：

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不同预分析条件下人血清中 12 种 T 辅助细胞相关细胞因子的稳定性

细胞因子是可溶性且易于分析的信号分子，可揭示有关免疫系统状态的重要线索。因此，它们用于免疫相关疾病的诊断和监测，其中需要严格控制样本的处理，包括储存和冷冻/解冻程序。在基础研究和临床试验中，人血清样本在处理前可以长期保存。科学实验室的存储空间通常有限，需要存储较少但较大的患者血清样本等分试样。同时处理的分析物数量也存在实际限制。此外，新的发现和技术进步可能会促使对迄今为止未被考虑或无法检测的分子进行分析。因此，血清样本的重复冷冻/解冻是一种可能的情况，提出了在这种条件下被测分析物的稳定性问题。为了解决这个问题，我们将掺入 T 辅助细胞相关细胞因子的血清样品在不同条件下进行多次冷冻/解冻循环，包括在 -20 °C 或 -80 °C 下储存和在 4 °C 下解冻，22 °C 和 37 °C，分别。冷冻前在室温下储存 4 小时后，TNF-α、IL-4、IL-17F 和 IL-22 的浓度降低。通常，在 -20 °C 下储存会导致细胞因子浓度降低。这与在 -80 °C 下的储存形成对比，后者提供了稳定的分析物浓度；不受反复冻融循环的影响。此处介绍的研究强调需要具有已知细胞因子浓度的哨兵样本作为冷冻/解冻过程的内部对照。