Rapid Quantification of Infliximab in Plasma and Serum Using MabTrack ELISA

MabTrack is an Enzyme-Linked Immunosorbent Assay (ELISA) designed for the rapid, reliable, and precise quantification of all pharmaceutical products that contain infliximab as their active ingredient, within human plasma and serum samples.

Article number M2920
Product group Quantitative quantitative measurement of infliximab drug levels
Technique Enzyme linked immunoassay (ELISA)
Synonyms Remicade, Remsima, Inflectra, Zessly, Flixabi

General information

The therapeutic chimeric antibody infliximab affects tumour necrosis factor alpha (TNF) and is frequently administered to patients who suffer from rheumatic arthritis, intestinal disorders, dermatological diseases and cancer. TNF plays an important role in inflammation; it causes for example pain, swollen joints and stiffness in rheumatoid arthritis patients. Inhibition of TNF is therefore believed to relieve some of these symptoms and thus to improve quality of life of patients.

Plasma and serum levels of TNF inhibitors are highly variable between patients, and clearly correlate to the clinical symptoms in patients. In approximately 8%-43% of the patients treated with infliximab, antibodies are formed directed towards infliximab. This can partially hamper the function of the TNF inhibitor and can cause a reduction in plasma concentration of the TNF inhibitor. Identification of drug levels can be important for patient adjusted treatment schedules, as low drug levels are frequently an indication for antibody formation against infliximab. In addition, low drug levels may be a sign of ineffectiveness of infliximab before rebound of clinical symptoms. Alternatively, it is proposed that in patients that respond well to infliximab, the dosing of infliximab can be reduced according to serum concentrations. Drug level tests can therefore help to adapt patient medication or to switch to an alternative TNF inhibitor. This infliximab level ELISA has been developed for fast, reproducible and specific quantification of infliximab concentrations in plasma and serum.

Test principles

For professional use only

The MabTrack level infliximab ELISA is a “sandwich-type” of enzyme immunoassay. In the microtiter plates, TNF is captured by monoclonal antibodies coated to polystyrene microtiter wells. The infliximab, present in the patient sample, the calibrator or the controls, binds to the TNF on the microtiter plate. Non-bound material is then removed by washing. Subsequently, a horseradish peroxidaselabeled monoclonal anti-drug antibody is added. This antibody binds to the infliximab/TNF/anti-TNF complex present in the microtiter well. After removal of non-bound HRP conjugate by washing, substrate solution is added to the wells. A coloured product is formed in proportion to the amount of infliximab present in the sample, calibrator and controls. After the reaction has been terminated by the addition of a stop solution, absorbance is measured in a microtiter plate reader. From the absorbance of samples and those of the calibrator curve, the concentration of infliximab can be determined by interpolation with the calibrator curve.

Clinical optimal ranges, e.g. therapeutic cut-off, were determined at Sanquin Diagnostic Services with the infliximab ELISA for rheumatoid arthritis to be minimally 3.0 µg/mL (Van de Bemt et al. 2013). For inflammatory bowel disease, the optimal range is 3.0–7.0 µg/mL (Vande Casteele et al.). The MabTrack level infliximab kit is calibrated on the WHO International Standard sold by the National Institute for Biological Standards and Control (#16/170).

Storage and Safety.

For in vitro diagnostic use only. Reagents should be stored at 2–8°C. Leaking or damaged vials must not be used. Reagents (unopened or opened) should not be used beyond the expiration date, which is printed on the label of the vial. The reagent cannot be assumed to be free from infectious agents.

Wash hands thoroughly after handling. Wear protective gloves/protective clothing/eye protection/face protection.

Care must be taken in the use and disposal of each container and its contents. Waste-disposal, after completion of the test, should be performed according to your laboratory regulations.

Causes serious eye irritation. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. If eye irritation persists: get medical advice/attention. Absorb spillage to prevent material damage.

Package contents

– The flat-bottom microtiter plate consists of 12 strips of 8 wells ready for use. All the wells are coated with TNF-specific mouse monoclonal antibody and recombinant TNF. The microtiter plate is vacuum sealed in a plastic pouch containing desiccant. The kit provides the flexibility to use the microtiter plate on separate occasions. Determine the number of strips required to test the desired number of samples plus 8 wells needed for running calibrators and controls. Remove strips that will not be used from the microtiter plate-frame and re-pack them in the plastic pouch containing the desiccant.
– After opening, all reagents and the microtiter plate strips may be used for ≤ 6 weeks if stored at 2–8 °C.
– Consult the enclosed information leaflet for the kit specific infliximab concentrations in calibrator 1-6 and in control 1 and control 2.

Mouse-anti-TNF/recombinant TNF pre-coated microtiter plate

12 x 8 wells


ready for use

Calibrator 1 – 6

6 x 1 mL

black caps M2912

ready for use

Control 1

1 x 1 mL

clear cap M2913

ready for use; therapeutic range

Control 2

1 x 1 mL

clear cap M2914

ready for use; sub-therapeutic range

Human anti-infliximab HRP-conjugate 1 x 12.5 mL brown bottle M2915 dilute 1:20 in distilled water
Wash buffer stock solution

1 x 50 mL

white bottle M1805

ready for use

HPE dilution buffer 1 x 50 mL white bottle M2940 ready for use
TMB substrate solution 1 x 12.5 mL brown bottle M1821 ready for use
Stop solution 0,18 M H2SO4 1 x 13.0 mL white bottle M1823  
Plate seals 10 x      


The kit has been designed for professional use only, the user must be trained and familiar with ELISA test procedures.

Test procedure

Specimen collection and preparation
1. Trough samples must be used to measure the concentration of infliximab, thus samples must be taken within 24 hours BEFORE the drug is injected to make sure that the indicated expected levels reflect the trough level of the patient.
2. Only serum and EDTA plasma can be used in the assay.
3. Separate plasma or serum from the blood cells within 4 hours after collection and perform the analyses immediately. If testing of the samples is delayed, they can be stored at 2-8 °C for 72 hours. If samples are not analysed within 72 hours, the samples must be stored frozen, they can be stored at ≤ -18 °C for 12 months.
4. Aliquot samples to avoid freeze-thaw cycles.
5. Prior to the assay, frozen samples must be thawed at room temperature. Do not use 37 °C or 56 °C water baths for thawing. 6. Mix the samples just before preparing the dilutions.


Find out more information about the scientific background of the product.

van den Bemt B.J.F. (2008)

Annals of the Rheumatic Diseases.

View study

Aarden L. (2008)

Current Opinion in Immunology.

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de Vries M.K. (2007)

Annals of the Rheumatic Diseases.

View study

Wolbink G.J. (2006)

Arthritis & Rheumatology.

View study

Van der Bemt B.J.F. (2013)

British Journal of Clinical Pharmacology.

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Vande Casteele N. (2015)


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Partners Anti Body Chain

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