Afonso Joana, Lopes Susana, Gonçalves Raquel, Caldeira Paulo, Lago Paula, Tavares de Sousa Helena, Ramos Jaime, Gonçalves Ana Rita, Ministro Paula, Rosa Isadora, Vieira Ana Isabel, Coelho Rosa, Tavares Patrícia, Soares João, Sousa Ana Lúcia, Carvalho Diana, Sousa Paula, da Silva João Pereira, Meira Tânia, Silva Ferreira Filipa, Dias Cláudia Camila, Chowers Yehuda, Ben-Horin Shomron, Magro Fernando
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal MedInUP, Centre for Drug Discovery and Innovative Medicines, University of Porto, 4200 Porto, Portugal.
Gastroenterology Department, Centro Hospitalar São João, Porto, Portugal.
Therap Adv Gastroenterol. 2016 Nov;9(6):781-794. doi: 10.1177/1756283X16658223. Epub 2016 Jul 26.
There is scant information on the accuracy of different assays used to measure anti-infliximab antibodies (ADAs), especially in the presence of detectable infliximab (IFX). We thus aimed to evaluate and compare three different assays for the detection of IFX and ADAs and to clarify the impact of the presence of circulating IFX on the accuracy of the ADA assays.
Blood samples from 79 ulcerative colitis (UC) patients treated with infliximab were assessed for IFX levels and ADAs using three different assays: an in-house assay and two commercial kits, Immundiagnostik and Theradiag. Sera samples with ADAs and undetectable levels of IFX were spiked with exogenous IFX and analyzed for ADAs.
The three assays showed 81-96% agreement for the measured IFX level. However, the in-house assay and Immundiagnostik assays detected ADAs in 34 out of 79 samples, whereas Theradiag only detected ADAs in 24 samples. Samples negative for ADAs with Theradiag, but ADA-positive in both the in-house and Immundiagnostik assays, were positive for IFX or IgG4 ADAs. In spiking experiments, a low concentration of exogenous IFX (5 µg/ml) hampered ADA detection with Theradiag in sera samples with ADA levels of between 3 and 10 µg/ml. In the Immundiagnostik assay detection interference was only observed at concentrations of exogenous IFX higher than 30 µg/ml. However, in samples with high levels of ADAs (>25 µg/ml) interference was only observed at IFX concentrations higher than 100 µg/ml in all three assays. Binary (IFX/ADA) stratification of the results showed that IFX+/ADA- and IFX-/ADAs+ were less influenced by the assay results than the double-positive (IFX+/ADAs+) and double-negative (IFX-/ADAs-) combination.
All three methodologies are equally suitable for measuring IFX levels. However, erroneous therapeutic decisions may occur when patients show double-negative (IFX-/ADAs-) or double-positive (IFX+/ADAs+) status, since agreement between assays is significantly lower in these circumstances.
关于用于检测抗英夫利昔单抗抗体（ADAs）的不同检测方法的准确性，尤其是在可检测到英夫利昔单抗（IFX）存在的情况下，相关信息很少。因此，我们旨在评估和比较三种不同的检测IFX和ADAs的方法，并阐明循环IFX的存在对ADA检测方法准确性的影响。
使用三种不同的检测方法对79例接受英夫利昔单抗治疗的溃疡性结肠炎（UC）患者的血样进行IFX水平和ADAs评估：一种内部检测方法以及两种商业试剂盒，即Immundiagnostik和Theradiag。将含有ADAs且IFX水平不可检测的血清样本加入外源性IFX，然后分析ADAs。
三种检测方法在测量的IFX水平上显示出81%-96%的一致性。然而，内部检测方法和Immundiagnostik检测方法在79个样本中的34个样本中检测到了ADAs，而Theradiag仅在24个样本中检测到了ADAs。Theradiag检测为ADA阴性，但在内部检测方法和Immundiagnostik检测方法中为ADA阳性的样本，IFX或IgG4 ADAs呈阳性。在加样实验中，低浓度的外源性IFX（5μg/ml）会妨碍Theradiag在ADA水平为3至10μg/ml的血清样本中检测ADA。在Immundiagnostik检测方法中，仅在外源性IFX浓度高于30μg/ml时才观察到检测干扰。然而，在ADA水平较高（>25μg/ml）的样本中，在所有三种检测方法中，仅在IFX浓度高于100μg/ml时才观察到干扰。结果的二元（IFX/ADA）分层显示，与双阳性（IFX+/ADAs+）和双阴性（IFX-/ADAs-）组合相比，IFX+/ADA-和IFX-/ADAs+受检测结果的影响较小。
所有三种方法同样适用于测量IFX水平。然而，当患者表现为双阴性（IFX-/ADAs-）或双阳性（IFX+/ADAs+）状态时，可能会做出错误的治疗决策，因为在这些情况下检测方法之间的一致性明显较低。
