Wong Hui-Lee, Pfeiffer Ruth M, Fears Thomas R, Vermeulen Roel, Ji Shaoquan, Rabkin Charles S
Infections and Immunoepidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Department of Health and Human Services, 6120 Executive Boulevard, Room 7073, Rockville, MD 20852, USA.
Cancer Epidemiol Biomarkers Prev. 2008 Dec;17(12):3450-6. doi: 10.1158/1055-9965.EPI-08-0311.
Cytokines are humoral regulatory molecules that act together in immunologic pathways underlying pathogenesis. Grossly elevated blood levels characterize certain diseases; variations within physiologic ranges could also have significance. We therefore evaluated the performance characteristics of a multiplex cytokine immunoassay.
We used a fluorescent bead-based (Luminex) immunoassay kit to simultaneously measure interleukin (IL) 1beta, IL2, IL4, IL5, IL6, IL7, IL8, IL10, IL12p70, IL13, IFNgamma, granulocyte colony-stimulating factor, and tumor necrosis factor-alpha. We tested identical aliquots of serum from 38 asymptomatic individuals on three different days and matched sets of serum, heparinized plasma, and acid citrate dextrose plasma from an additional 38 healthy donors expected to have low cytokine concentrations. We applied multiple imputation to calculate unbiased reproducibility estimates for measurements below the limits of detection. Correlations among the cytokines were assessed by Spearman rank order coefficients and principal components analyses.
Of the 13 cytokines, 3 were undetectable (IL1beta, IL2, IL5) in more than half of the serum samples. Coefficients of variation for replicate serum measurements ranged from 18% to 44%, with intraclass correlation coefficients ranging from 55% to 98%. Only IL4, IL6, and IL8 had statistically significant correlations (Spearman rho, 0.42-0.94) between serum and acid citrate dextrose or heparin plasma levels.
Interindividual differences outweigh substantial laboratory variation for these assays, yielding high intraclass correlation coefficients despite unimpressive coefficients of variation. Plasma measurements generally are not reflective of serum levels and hence are not interchangeable. With their small volume, low cost per test, and multiplex capacity, Luminex-based cytokine assays have potential utility for epidemiologic studies.
细胞因子是体液调节分子，在发病机制的免疫途径中共同发挥作用。某些疾病的特征是血液水平显著升高；生理范围内的变化也可能具有重要意义。因此，我们评估了一种多重细胞因子免疫测定的性能特征。
我们使用基于荧光微球（Luminex）的免疫测定试剂盒同时测量白细胞介素（IL）1β、IL2、IL4、IL5、IL6、IL7、IL8、IL10、IL12p70、IL13、干扰素γ、粒细胞集落刺激因子和肿瘤坏死因子-α。我们在三个不同的日子对38名无症状个体的相同血清等分试样进行了检测，并检测了另外38名预期细胞因子浓度较低的健康供体的匹配血清、肝素化血浆和枸橼酸葡萄糖酸血浆。我们应用多重填补法来计算低于检测限的测量的无偏重现性估计值。通过Spearman等级系数和主成分分析评估细胞因子之间的相关性。
在13种细胞因子中，超过一半的血清样本中检测不到3种（IL1β、IL2、IL5）。重复血清测量的变异系数范围为18%至44%，组内相关系数范围为55%至98%。只有IL4、IL6和IL8在血清与枸橼酸葡萄糖酸或肝素血浆水平之间具有统计学显著相关性（Spearman ρ，0.42 - 0.94）。
对于这些测定，个体间差异超过了显著的实验室变异，尽管变异系数不太理想，但仍产生了较高的组内相关系数。血浆测量通常不能反映血清水平，因此不可互换。基于Luminex的细胞因子测定因其体积小、每次检测成本低和多重检测能力，在流行病学研究中具有潜在用途。
