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Tysabri® (Natalizumab) Immunogenicity Test

Test Code: 30040

Cpt Code:

83516 (x1)

Clinical Utility

New drugs such as Tysabri® offer highly specific and effective therapy for Multiple sclerosis patients. However, Tysabri® loses effectiveness when patients develop antibodies to the drug. Detecting these antibodies early allows healthcare providers the opportunity to prescribe alternative therapy and avoid the cost associated with failed therapy.


The assay is intended to detect anti-Tysabri antibodies in serum. In this binding assay, samples are run in both a screening and a confirmation assay on the same plate. The threshold for positive sample responses is 500 ng/mL, established by Biogen Idec to detect antibodies that are clinically meaningful. The performance characteristics of this test were determined by Viracor-IBT Laboratories. This test has not been cleared or approved for diagnostic use by the U.S. Food and Drug Administration.

Assay Range

Samples will be reported as either postive or negative

Turnaround Time

Setup: Wednesday. TAT 5-7 business days from receipt of specimen.

Specimen Information

serum - NY approved. 1 mL. Collect sufficient whole blood in a RED top collection tube to obtain 1 mL of serum. Serum separator tubes may be used. The time and date of sample collection should be noted. Allow each whole blood sample to clot for 30 minutes at ambient temperature and centrifuge it within 1 hour of collection. Following centrifugation, transfer the serum into an appropriately sized transfer tube. If serum separator tubes are used, care must be taken to ensure gel is not pipetted out with the sample while aliquoting. Samples should be frozen when possible. Refrigerated specimens are acceptable. Frozen samples should be shipped on dry ice within 2 days of collection. Refrigerated samples should be shipped on ice packs within two days of collection.

2 weeks refrigerated, > 2 weeks freeze


Specimens are approved for testing in New York only when indicated in the Specimen Information field above.

The CPT codes provided are based on Viracor-IBT's interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for general informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. Viracor-IBT assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material.


van Regenmortel, M.H.V., Boven, K., & Bader, F. August 2005. Biopharm International. Immunogenicity of Biopharmaceuticals: An Example from Erythropoietin.

Mire-Sluis, A.R., Barrett, Y.C., et al. FDA. Recommendations for the Design and Optimization of Immunoassays Used in the Detection of Host Antibodies Against Biotechnology Products.

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