240: Acquisition of CMV-specific CD8+ T cell memory during primary CMV infection in lung transplant recipients

Abstract

reactivation. Methods and Materials: A longitudinal cohort of LTR were recruited from the time of transplantation and followed prospectively for one year. All CMV “at-risk” patients received 5 months antiviral prophylaxis. CMV load was assessed in the blood and BAL at the time of routine bronchoscopic evaluation. At these same time points, QuantiFERON-CMV was used to detect CMV CD8 T-cell immunity in the blood by measuring IFN-g secreted from stimulated T-cells previously exposed to CMV. Results: 250 samples were collected from 49 LTR (CMV D /R-, n 11; D /R , n 21; D-/R , n 9; D-/R-, n 9). As expected CMV-specific T-cell immunity was not detected in any of the CMV D-/RLTR. CMV-specific CD8 T cells could be detected in all CMV ve LTR and although the levels varied between patients, the presence of CMV-specific immunity appeared protective against significant CMV reactivation. In CMV “at-risk” LTR levels of CMV immunity generally increased with time from transplant and this was particularly marked following an episode of CMV reactivation where levels of CMV immunity often reset at a significantly higher level compared with baseline. CMV reactivation episodes were most likely in the CMV mismatched LTR, particularly once antiviral prophylaxis was ceased, and in these patients QuantiFERON-CMV tracked the development of the primary immune response to CMV (median 33wks post-tx). Conclusions: The ability of the QuantiFERON-CMV assay to measure CMV-specific CD8 T-cell function provides significant insights into the dynamics of CMV reactivation and immunity in LTRs, and offers the potential for improved CMV risk stratification and individualised antiviral prophylaxis in the future. Research Funding; Cellestis.