Pre-transplant assessment of pp65-specific CD4 T cell responses identifies CMV-seropositive patients treated with rATG at risk of late onset infection.

Assessment of CMV-specific T cell immunity might be a useful tool in predicting CMV infection after solid organ transplantation. We have investigated CD4 and CD8 T-cell responses to CMV pp65 and IE-1 antigens in a prospective study of 28 CMV-seropositive kidney transplant recipients who were administered lymphocyte-depleting antibodies (Thymoglobulin®) as induction treatment and with universal prophylaxis for CMV infection. The response was analyzed by intracellular flow cytometry analysis of IFN-γ production in pretransplant samples and at 1, 6, 12 and 24 months post-transplant. Overall, only pretransplant CD4 T-cell responses to pp65 were significantly lower (p = .004) in patients with CMV replication post-transplant. ROC curve analysis showed that pre-transplant frequencies of pp65-specific CD4 + T cells below 0.10% could predict CMV infection with 75% sensitivity and 83.33% specificity (AUC: 0.847; 95% CI: 0.693-1.001; p = .0054) and seem to be mandatory for efficient control of CMV viral replication by the host immune system. In conclusion, the functional assessment of CMV-specific CD4 T-cell immunity pretransplant in seropositive patients may allow the identification of Thymoglobulin®-treated kidney transplant recipients at risk of developing CMV infection post-transplantation.