Cytomegalovirus-specific T cells restricted for shared and donor human leukocyte antigens differentially impact on Cytomegalovirus reactivation risk after allogeneichematopoietic stem cell transplantation

After allogeneic hematopoietic stem cell transplantation (allo-HSCT), the emergence of circulating Cytomegalovirus(CMV)-specific T cells correlates with protection from CMV reactivation, an important risk factor for non-relapse mortality. However, functional assays measuring CMV-specific cells are time-consuming and often inaccurate at early timepoints. We report results of a prospective single-center non-interventional study which identifies the enumeration of Dextramer-positive CMV-specific lymphocytes as a reliable and early predictor of viral reactivation. We longitudinally monitored 75 consecutive patients for 1 year after allo-HSCT (n=630 samples). The presence of ≥0.5 CMV-specific CD8+ cells//L at day+45 was an independent protective factor from subsequent clinicallyrelevant reactivation in univariate(p.