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Kidney Week

Abstract: FR-PO898

Validation of a Cellular Assay for Detection of Over-Immunosuppression in Kidney Recipients: An Interim Report

Session Information

Category: Transplantation

  • 1802 Transplantation: Clinical

Authors

  • Bouchard-Boivin, François, CHU de Québec - Laval University, Quebec, Quebec, Canada
  • Desy, Olivier, CHU de Québec - Laval University, Quebec, Quebec, Canada
  • Beland, Stephanie, CHU de Québec - Laval University, Quebec, Quebec, Canada
  • De Serres, Sacha A., CHU de Québec - Laval University, Quebec, Quebec, Canada
Background

The transplantation community lacks a clinical tool to diagnose over-immunosuppression, resulting in major clinical side effects. Recently, our laboratory has unveiled an association between the cytokine secretion of intermediate CD14+CD16+ monocytes stimulated in vitro with Epstein-Barr Virus (EBV) peptides and the status of over-immunosuppression in a prospective, longitudinal cohort of kidney recipients. We are now validating the test in a large cross-sectional cohort.

Methods

We recruited 120 unsensitized kidney recipients, isolated their peripheral blood mononuclear cells at 2 timepoints (3mo interval) and stimulated the cells with EBV peptides overnight. Staining for viability, CD14 and CD16 and tumor necrosis factor (TNF-α) was performed to quantify cytokine secretion of intermediate monocytes by flow cytometry.

Results

We report interim results of the first 24 patients. Mean±SD age was 56±13 years and mean glomerular filtration rate was 46±15 mL/min/1.73m2. Median time (25-75th percentiles) post-transplant was 2 (1 – 8) years. Patients were treated with prednisone, mycophenolate and tacrolimus. Eleven patients received induction therapy. There were 15 controls and 9 cases, including 7 opportunistic infections, 1 recurring bacterial infections and 1 de novo neoplasia, events which happened on mean of 1.4±2.0 months after blood was withdrawn for the assay. Mean TNF-α-positive cells on the first sample was 70±20% for the controls and 53±15% for the cases. All but one patient who scored below the previously established threshold (<73% TNF-α) were confirmed on the second sample. AUC of the ROC curve was 0.83±0.09 (p<0.01). Preliminary values of sensibility, specificity, positive and negative predictive values were 89% (8/9), 60% (9/15), 57% (8/14) and 90% (9/10) respectively.

Conclusion

These interim results seem to confirm that over-immunosuppressed patients have lower intermediate monocyte response to EBV peptides. Furthermore, they show high sensibility and negative predictive value, similar to the derivation cohort. This assay could allow ruling out over-immunosuppressive state in the clinical setting.