Cord blood transplantation (CBT) frequently can be complicated by cytomegalovirus (CMV) infection, which is required for administration of antiviral chemotherapy. Although the naïve feature of cord blood T-cells were suggested to increase the incidence of CMV infection, the underlying mechanism is not fully elucidated. CMVresponsive T-cells detected by intracellular interferon-gamma (IFN-γ) staining and CMV-specific CD8+ T- cells detected by MHC class I tetramers were analyzed in healthy adult blood and recipient blood post-CBT. CMV antigenemia was accompanied in thirty-two of thirty-nine recipients (82%) post-CBT. CMV-responsive CD4+ T-cells were detected in all recipients with CMV antigenemia within 120 days post CBT [first date of CMV- responsive CD4+ T-cell detection, median 41 days, (32-90 days); peak frequencies 18±21 cells/μl, n=22]. In contrast, CMV-responsive CD8+ T-cells were detected in only 38% of patients with CMV antigenemia with similar frequencies (peak frequencies 18±24 cells/μl, n=8). CMV-responsive CD4+ T-cells but not CMV responsive CD8+ T-cells were significantly induced in all recipients with CMV antigenemia. Rapid reconstitution of CMV-responsive CD4+ T-cells might suppress the progression of CMV disease from CMV antigenemia.
