T-Track-CMV and QuantiFERON-CMV assays for prediction of protection from CMV reactivation in kidney transplant recipients

Background: Assays detecting CMV-specific cell-mediated immunity (CMI) may support the current management of CMV infection in solid-organ transplant (SOT) recipients, by allowing a better risk assessment and adjusting antiviral treatment. Objectives: The primary endpoint was the performance of two tests measuring CMV-specific interferon-gamma production, both approved for commercial use in clinical settings. Secondarily, we determined a cut-off for the cellular immune response, which protects against CMV reactivation/infection. Study design: Thirty kidney transplant (KTx) patients were stratified according to their CMV-IgG status pretransplantation (Tx) and were divided into two groups: pre-emptive (donor-/recipient+, donor+/recipient+) and prophylaxis (donor+/recipient-). An ELISpot (T-Track-CMV) was performed at month 1 post-Tx (preemptive group) and end of prophylaxis and one month thereafter (prophylaxis group). An ELISA (QuantiFERONCMV) was performed every 2-4 weeks (pre-emptive) or monthly (prophylaxis), in parallel to the CMV viral load (PCR). Results: A good positive agreement was obtained between the QuantiFERON-CMV or T-Track-CMV and the CMV-IgG (kappa= 0.839 and 0.824, respectively). A cut-off of 19.5 spot forming units (SFU)/200,000 lymphocytes for the T-Track-CMV IE-1 (AUC= 0.802, sensitivity 45%, specificity 100%) and 495 SFU/200,000 lymphocytes for the T-Track-CMV pp65 (AUC= 0.617, sensitivity 11%, specificity 100%) was defined to assess protection against reactivation. The QuantiFERON-CMV performed modestly (AUC= 0.477, cut-off 85.1 IU/ml). Conclusions: The QuantiFERON-CMV and T-Track-CMV enable the functional assessment of CMV-specific CMI in KTx recipients. In combination with CMV viral load monitoring, T-Track-CMV results could stratify patients at risk of CMV reactivation/infection.