{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,28]],"date-time":"2025-10-28T05:52:40Z","timestamp":1761630760427,"version":"3.38.0"},"reference-count":19,"publisher":"SAGE Publications","issue":"6","license":[{"start":{"date-parts":[[2016,7,28]],"date-time":"2016-07-28T00:00:00Z","timestamp":1469664000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Therap Adv Gastroenterol"],"published-print":{"date-parts":[[2016,11]]},"abstract":"<jats:sec><jats:title>Background:<\/jats:title><jats:p> 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. <\/jats:p><\/jats:sec><jats:sec><jats:title>Methods:<\/jats:title><jats:p> 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. <\/jats:p><\/jats:sec><jats:sec><jats:title>Results:<\/jats:title><jats:p> The three assays showed 81\u201396% 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 \u00b5g\/ml) hampered ADA detection with Theradiag in sera samples with ADA levels of between 3 and 10 \u00b5g\/ml. In the Immundiagnostik assay detection interference was only observed at concentrations of exogenous IFX higher than 30 \u00b5g\/ml. However, in samples with high levels of ADAs (&gt;25 \u00b5g\/ml) interference was only observed at IFX concentrations higher than 100 \u00b5g\/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. <\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions:<\/jats:title><jats:p> 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. <\/jats:p><\/jats:sec>","DOI":"10.1177\/1756283x16658223","type":"journal-article","created":{"date-parts":[[2016,7,27]],"date-time":"2016-07-27T00:33:36Z","timestamp":1469579616000},"page":"781-794","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":16,"title":["Detection of anti-infliximab antibodies is impacted by antibody titer, infliximab level and IgG4 antibodies: a systematic comparison of three different assays"],"prefix":"10.1177","volume":"9","author":[{"given":"Joana","family":"Afonso","sequence":"first","affiliation":[{"name":"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"}]},{"given":"Susana","family":"Lopes","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar S\u00e3o Jo\u00e3o, Porto, Portugal"}]},{"given":"Raquel","family":"Gon\u00e7alves","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Hospital de Braga, Braga, Portugal"}]},{"given":"Paulo","family":"Caldeira","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar do Algarve, Faro, Portugal"}]},{"given":"Paula","family":"Lago","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar do Porto, Porto, Portugal"}]},{"given":"Helena","family":"Tavares de Sousa","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar do Algarve, Portim\u00e3o, Portugal Departament of Medicine e Medical Biosciences, University of Algarve, Faro, Portugal"}]},{"given":"Jaime","family":"Ramos","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar de Lisboa, Lisboa, Portugal"}]},{"given":"Ana Rita","family":"Gon\u00e7alves","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar Lisboa Norte, Lisboa, Portugal"}]},{"given":"Paula","family":"Ministro","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Hospital de S. Teot\u00f3nio, Viseu, Portugal"}]},{"given":"Isadora","family":"Rosa","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Instituto Portugu\u00eas de Oncologia de Lisboa, Lisboa, Portugal"}]},{"given":"Ana Isabel","family":"Vieira","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Hospital Garcia de Orta, Almada, Portugal"}]},{"given":"Rosa","family":"Coelho","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar S\u00e3o Jo\u00e3o, Porto, Portugal"}]},{"given":"Patr\u00edcia","family":"Tavares","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar S\u00e3o Jo\u00e3o, Porto, Portugal"}]},{"given":"Jo\u00e3o","family":"Soares","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Hospital de Braga, Braga, Portugal"}]},{"given":"Ana L\u00facia","family":"Sousa","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar do Algarve, Faro, Portugal"}]},{"given":"Diana","family":"Carvalho","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Centro Hospitalar de Lisboa, Lisboa, Portugal"}]},{"given":"Paula","family":"Sousa","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Hospital de S. Teot\u00f3nio, Viseu, Portugal"}]},{"given":"Jo\u00e3o Pereira","family":"da Silva","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Instituto Portugu\u00eas de Oncologia de Lisboa, Lisboa, Portugal"}]},{"given":"T\u00e2nia","family":"Meira","sequence":"additional","affiliation":[{"name":"Gastroenterology Department, Hospital Garcia de Orta, Almada, Portugal"}]},{"given":"Filipa","family":"Silva Ferreira","sequence":"additional","affiliation":[{"name":"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"}]},{"given":"Cl\u00e1udia Camila","family":"Dias","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal"}]},{"given":"Yehuda","family":"Chowers","sequence":"additional","affiliation":[{"name":"Gastroenterology 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