Cytomegalovirus Prophylaxis versus Pre-emptive Strategy: Different CD4+ and CD8+ T Cell Reconstitution after Allogeneic Hematopoietic Stem Cell Transplantation.

Reconstitution of T cells after transplantation is a determinant of the long-term success of the procedure, and the correlation with T cell recovery and cytomegalovirus reactivation and disease is well known. We evaluated 110 patients who underwent transplantation: 55 received pre-emptive antiviral treatment, and in the other 55 patients, prophylaxis with letermovir was employed. A progressive statistically significant difference in T cell reconstitution between the 2 groups was observed, starting from day +60 with faster recovery in the pre-emptive group. Moreover, a higher incidence of cytomegalovirus reactivation was observed in prophylactic group after discontinuation of letermovir, and subsequent antiviral treatment has been necessary. Our findings confirm, as previously reported, that cytomegalovirus reactivation is a potent stimulator of T cell function.