Early Recovery of Immunity after Cord-Blood Transplantation in Children: Qualitative Features and Impact of Cytomegalovirus Infection

Abstract

This study investigated immune recovery and the effect of cytomegalovirus (CMV) infection on the early stages of T-lymphocyte recovery after cord-blood transplantation (CBT) from unrelated donors to 24 children. In addition, 15 children who were recipients of a bone-marrow transplant (BMT) were studied concomitantly. The main objectives of the study were whether lymphocytes from CBT recipients were capable of rapid qualitative differentiation in the effector memory (EM) stage, of regenerating de novo naïve cells and of responding to CMV infection. Results showed that CB lymphocytes were mainly differentiated into the EM stage at 3 months and into the naïve stage at 6 months. CMV infection induced a dramatic increase in CD8 but not CD4 T-cell counts, and differentiation into the EM stage with high perforin contents. Our data suggest that CB lymphocytes are capable of rapid differentiation in children, but stabilization of lymphocyte counts in children is associated with effective naïve subset regeneration at 6 months. Moreover, the T-cell repertoire is capable of rapid adjustment when CMV infection occurs.