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RETROSPECTIVE ANALYSIS OF MONITORING SMALL BOWEL TRANSPLANT RECIPIENTS WITH THE CYLEX® IMMUKNOW™ ASSAY.
Richard J. Kowalski, PhD, Diane R. Post, Carol Bentlejewski, Clyde Harris, Kareem Abu Elmagd, MD and Adriana Zeevi, PhD. Columbia MD, USA, Cylex Inc., 21045, Product Development and Pittsburgh PA, USA, Thomas E. Starzl Transplant Institute, 15261, Pathology and Surgery.

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Background: To monitor induction and maintenance of tolerance a tool is needed to measure the level of immune activation of the transplant recipient. In a double blind retrospective study the Cylex® ImmuKnow™ Assay, approved by the FDA for the assessment of cell-mediated immunity, was used to monitor the immune response to immunosuppressant therapy changes in small bowel transplant recipients.
Methods: The functional immune responses of transplant recipients enrolled in a Tacrolimus monotherapy weaning protocol at UPMC were monitored using the Cylex® ImmuKnow™ Assay. The immune status of transplant recipients at different points in time post transplant was compared to changes in the dose of immunosuppressant therapy administered and histological examinations of biopsies.
Results: Over 460 whole blood samples were obtained sequentially from 22 patients following transplantation and tested with the ImmuKnow Assay. Data were correlated with clinical interventions, changes in drug dosing, drug levels in the blood and biopsies. Patients that were successfully weaned of Tacrolimus and remained stable showed immune function levels of 290 ng/mL ATP. In contrast, patients who required additional immunosuppressants were at a higher level of immune activation (403 ng/mL ATP). Patients who rejected and received rescue therapy demonstrated the highest level of immune activation (664 ng/mL ATP).
Conclusions: Results demonstrate that the assessment of immune function provides an objective tool for determining the timing and rate of drug tapering for individualizing the management of transplant recipients.