Early cytomegalovirus-specific T-cell response and estimated glomerular filtration rate identify patients at high risk of infection after renal transplantation

Background. Assessing the risk of cytomegalovirus (CMV) viremia in kidney transplant recipients (KTR) may be helpful to indicate in which patient it is worth starting antiviral treatment during preemptive strategy. Methods. In 40 CMV-seropositive KTR preemptively treated with ganciclovir, we used interferon (IFN)-gamma ELISpot test to evaluate whether monitoring T cells directed against phosphoprotein (pp) 65 and immediate early (IE)-1 antigens could predict the onset of viremia. Results. CMV viremia occurred in 24 patients (60%) within 120 days after transplantation. Non-viremic patients had higher anti-pp65, anti-IE-1 T cells, and estimated glomerular filtration rate (eGFR) in the first 90 days after transplantation. At logistic regression, anti-pp65, anti-IE-1 T cells, and eGFR measured at day 30 were significantly associated with CMV infection. Cutoff values of 15 spot-forming cells (SFCs)/200,000 peripheral blood mononuclear cells (PBMCs) for anti-IE, 40 SFCs/200,000 PBMCs for anti-pp65, and 46.6 mL/min/1.73 m(2) for eGFR, respectively, predicted the risk of CMV infection with high sensitivity and specificity (area under the receiver operating characteristic curve >0.75). Using a classification tree model, we identified as high-risk patients those showing anti-pp65 <42 SFCs/200,000 PBMCs and eGFR <62 mL/min/1.73 m(2), as well as anti-pp65 >= 42 and anti-IE-1 <6.5 SFCs/200,000 PBMCs. Conclusion. Monitoring CMV-specific T-cell responses and eGFR in the first month post transplant can identify patients at high risk of CMV infection, for whom preemptive antiviral therapy is recommended.