Cytomegalovirus (CMV) is the most frequent infection during the first year after transplantation causing both direct and indirect effects that can impact patient outcomes. Adaptive immune responses consisting of B and T cells represent the main defence against infection. Neutralizing antibodies are a major component of the humoral immune response, however the protective role of neutralizing antibodies remains unclear. The CMV-specific T-cell response, consisting of CD4+ and CD8+ T cellsexpressing interferon-γ (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin-2 (IL-2), has been widely studied, and has been shown to play a critical in the control of the infection. Thus, a reduced number of IFN-γ-D8+ T-cells was found in individuals with higher risk of CMV replication and disease. Based on the role of the T-cell immune response in controlling CMV infection, several clinical studies have described the use of immune response monitoring in order to assess the risk of CMV viremia and disease in cohorts of transplant patients at high and low risk for CMV infection. In addition, pretransplant immune status has been studied to predict the risk of developing CMV infection after transplantation. Different assays available for CMV-specific immune monitoring have been used for predicting disease and viremia such as, ELISPOT, QuantiFERON, the major histocompatibility complex (MHC)-multimer-based assay and intracellular cytokine staining and flow cytometry analysis. Most of these methods are based on the detection of the secretion of INF-γ after stimulation with specific viral antigens or viral lysates. Data are accumulating suggesting that immune monito ring of the CMV-specific T cell response may be used as additional tool for stratifying patient risk for CMV infection as well as for guiding antiviral therapy after transplantation in combination with viral load monitoring. However, few studies are available demonstrating safety and feasibility of using immune monitoring for guiding patient management based on the results of the immune response.

In this plenary session I will present our results regarding the kinetics of the adaptive immune response after transplantation in solid organ transplant recipients at high and low risk for CMV infection after transplantation. In addition, I will discuss our experience in the clinical utility of immune response monitoring for stratifying patient risk for CMV infection and guiding antiviral therapy based