Center for Translational Medicine, Medical Department I, Marien Hospital Herne, University Hospital of the Ruhr-University Bochum, Hölkeskampring 40, 44625 Herne, Germany; Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin-Brandenburg Center for Regenerative Therapies, Augustenburger Platz 1, 13353 Berlin, Germany.
Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin-Brandenburg Center for Regenerative Therapies, Augustenburger Platz 1, 13353 Berlin, Germany.
Cytokine. 2020 May;129:155044. doi: 10.1016/j.cyto.2020.155044. Epub 2020 Feb 25.
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.
细胞因子是可溶性的，易于分析的信号分子，可以提供有关免疫系统状态的重要线索。因此，它们可用于免疫相关疾病的诊断和监测，在这些疾病中，需要严格控制包括储存和冻融程序在内的样本处理。在基础研究和临床试验中，人血清样本可以在处理之前进行长期储存。科学实验室的储存空间通常有限，这需要储存更少但更大的患者血清样本等分样。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分析以前未考虑或无法检测到的分子。因此，血清样本的反复冻融是一种可能的情况，这就提出了在这种条件下测量分析物的稳定性问题。为了解决这个问题，我们将添加了 T 辅助细胞相关细胞因子的血清样本在不同条件下进行了多次冻融循环，包括在-20°C 或-80°C 下储存以及在 4°C、22°C 和 37°C 下分别解冻。在冷冻前于室温下储存 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-80°C 下储存形成对比，后者会使分析物浓度保持稳定；不受反复冻融循环的影响。本研究强调了需要具有已知细胞因子浓度的哨兵样本作为冻融过程的内部对照。
