Department of Renal Medicine, Aarhus University Hospital, Skejby, Denmark.
Scand J Clin Lab Invest. 2012 Dec;72(8):583-92. doi: 10.3109/00365513.2012.713175. Epub 2012 Aug 30.
Interleukin 18 (IL-18) is an important pro-inflammatory cytokine investigated in end-stage renal disease (ESRD) and several autoimmune and inflammatory diseases. The quantitative colorimetric sandwich ELISA test kit from MBL is the most frequently used ELISA kit for IL-18 detection. Recently, a new bead-based proximity assay named AlphaLISA was developed. The aim of this study was to compare the performance of these two kits and to evaluate aspects of sample handling on IL-18 measurements.
Measurements of IL-18 were performed on plasma samples from 11 ESRD-patients in regular haemodialysis treatment and 10 healthy volunteers.
We found a significant difference between assays corresponding to a factor of 6.4 (6.0; 6.7), p < 0.0001. Agreement was excellent with intra-class correlation coefficient 0.95. MBL had lower inter-assay variation, batch-to-batch variation and day-to-day variation. Spiking with recombinant IL-18 resulted in a mean recovery of 91 ± 7 (MBL) vs. 135 ± 17% (AlphaLISA), p < 0.0001. Both kits performed equally well when linearity was investigated. IL-18 was stable over a period of 424 days when plasma samples were stored at - 80°C. When blood samples were stored at room temperature mean IL-18 concentration changed significantly between 0, 1, 6, and 24 hours after sampling (p = 0.0213). No significant change was found with storage at 5°C. Severe haemolysis affected IL-18 measurements, whereas repeated freezing and thawing showed no effect. Mean IL-18 concentration was significantly higher in ESRD-patients compared to healthy subjects regardless of assay.
Assay performance was best with the MBL-kit, although AlphaLISA was less time consuming when measuring plasma IL-18.
白细胞介素 18（IL-18）是一种重要的促炎细胞因子，在终末期肾病（ESRD）和几种自身免疫性和炎症性疾病中得到了研究。MBL 的定量比色夹心 ELISA 检测试剂盒是检测 IL-18 最常用的 ELISA 试剂盒。最近，开发了一种名为 AlphaLISA 的新型基于珠的接近测定法。本研究的目的是比较这两种试剂盒的性能，并评估样品处理对 IL-18 测量的影响。
对 11 名接受常规血液透析治疗的 ESRD 患者和 10 名健康志愿者的血浆样本进行 IL-18 测量。
我们发现两种测定方法之间存在显著差异，对应因子为 6.4（6.0；6.7），p<0.0001。组内相关系数为 0.95，一致性极好。MBL 的批间变异性、批内变异性和日间变异性均较低。用重组 IL-18 加标后，回收率分别为 MBL 组 91±7%和 AlphaLISA 组 135±17%，p<0.0001。当线性度被调查时，两种试剂盒的性能相同。当将血浆样本储存在-80°C 时，IL-18 在 424 天内稳定。当室温下储存血液样本时，采血后 0、1、6 和 24 小时，IL-18 浓度的变化有显著差异（p=0.0213）。在 5°C 下储存未发现显著变化。严重溶血会影响 IL-18 的测量，而反复冻融则没有影响。无论使用哪种检测方法，ESRD 患者的 IL-18 浓度均明显高于健康受试者。
尽管 AlphaLISA 在测量血浆 IL-18 时耗时更少，但 MBL 试剂盒的检测性能最佳。
