Inflammatory bowel diseases are a multifactorial, lifetime ailments, characterized by a chronic intestinal inflammation. The two most notable diseases are Crohn's disease and ulcerative colitis. Treatment is based on a combination of different types of medicine, and – in the case of standard therapy failure – it includes biological drugs such as tumor necrosis factor alpha inhibitors, for instance infliximab. The patient can start to produce anti-infliximab antibodies, which leads to a lower drug response and a possible reactivation of the disease that was already in remission. Determining these antibodies in the patients' blood is not universally routinely practiced (yet), but it is nevertheless of great importance in deciding how to pursue with the treatment. The main issue with commonly used assays (e.g. bridging ELISA) for determining these antibodies is that they lack the ability to detect them in the presence of drug.
Our main purpose was to optimize a bridging enzyme-linked immunosorbent assay with an acidic pre-treatment protocol as an efficient, drug tolerant anti-infliximab antibody detection method, previously studied by a Belgian research group, and to test this optimized method on a cohort of samples of patients with inflammatory bowel disease, treated with infliximab. We assumed that after optimising this method we would also be able to detect antibodies against infliximab, previously bound in immune complexes with infliximab, in samples with higher concentrations of infliximab. We optimized the already published method by evaluating the success of the infliximab depletion in the pre-treatment samples and the success of the drug tolerant anti-ifliximab antibody detection. Even though we did not detect anti-infliximab antibodies in any of the 42 patients' samples with the optimized method, we did howewer prove that we could detect anti-infliximab antibodies at a higher primary infliximab sample concentration than the Belgian research group could. Following new modifications, longitudinal monitoring and receiving positive results after testing, this method could have potential for getting inducted into routine clinical practice, considering that the medical community aims to improve the process of early detection of unsuccesful treatment and improve the patient's prognosis in the future.
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