Test Catalog

Test ID: INFXR    
Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum

Method Description Describes how the test is performed and provides a method-specific reference

Infliximab Quantitation:

This test is performed using liquid-chromatography and tandem mass spectrometry. Preanalytical sample preparation includes a trypsin digestion; 2 unique clonotypic peptides from the heavy and light chains of the infliximab chimeric structure (IgG1 kappa) are monitored.(Willrich MA, Murray DL, Barnidge DR, et al: Quantitation of infliximab using clonotypic peptides and selective reaction monitoring by LC-MS/MS. Int Immunopharmacol. 2015;28:513-520)


Infliximab Antibodies:

This lab developed immunoassay is designed to measure antibodies-to-infliximab (ATI) in human serum by means of electrochemiluminescence (ECL) on the MesoScale Discovery (MSD) platform. The assay uses a "bridging" format in which the ATI forms a link between biotin labeled infliximab and SULFO-Tag labeled infliximab. The biotin binds to a streptavidin (SA) coated surface and the SULFO-Tag creates a signal in the presence of a conjugate following application of an electric current. During sample preparation, serum is mixed with acetic acid to break the infliximab/ATI complex. Biotinylated and SULFO-Tagged infliximab are then added and bind with ATI that is present in the sample. After the incubation with the labeled drug, the calibrators, controls, and samples are added to a SA plate that has been blocked with a solution of bovine serum albumin (BSA). The biotinylated infliximab then binds to the SA plate. After an incubation period, the SA plate is washed and MSD read buffer is added. Immediately after the addition of read buffer, the plate is analyzed. The read buffer provides an appropriate chemical environment for ECL when a voltage is applied to the electrodes on the plate. This voltage causes bound SULFO-Tagged infliximab to emit measureable light. The intensity of emitted light is measured and correlated to a set of standards with known concentrations of ATI by means of a 4-point logistics curve fitting method.(Willrich M, Balsanek J, Ladwig P, et al: A-374 Antibodies-to-Infliximab: Assay Development and Correlation with Infliximab Concentrations in Serum Samples of Treated Patients. AACC Annual Meeting; Chicago: AACC Press; 2014 pS110; Balsanek J, Willrich MAV, Murray DL, Snyder M: Sa1268 Clinical Development of an Electrochemiluminescent Immunoassay to Measure Antibodies-to-Infliximab. Gastroenterology. 2014;146[5]:S-248)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

INFX: Monday, Wednesday, Thursday

INXAB: Monday, Wednesday, Friday

Report Available The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

3 to 6 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

2 weeks

Performing Laboratory Location Indicates the location of the laboratory that performs the test