Preliminary exploration of HLA-A 1101-restricted human cytomegalovirus glycoprotein B-specific CD8⁺ T cells in allogeneic stem-cell transplant recipients.

T-cell responses directed against human cytomegalovirus (HCMV) glycoprotein B (gB) contribute to protective immunity against HCMV infection in both animal models and humans. However, the gB-specific human CD8(+) T cell responses remain poorly understood. gB antigen-specific CD8(+) T cells were stained with seven major histocompatibility complex (MHC)-peptide pentamers in 16 human leukocyte antigen (HLA)-A 1101-positive, HCMV-seropositive patients following hematopoietic stem cell transplantation (HSCT). Of these seven pentamers, the most frequent CD8(+) T-cell responses were directed against the gB332-340 peptide. These gB332-340-specific CD8(+) T cells were strongly associated with the presence of plasma HCMV immunoglobulin M in all HSCT recipients and exhibited a probable causal relationship with the level of pp65 antigenemia. Together, these data suggest a role for gB332-340-specific CD8(+) T cells in HCMV reactivation after HSCT. Furthermore, the pentamer assay may be valuable in detecting antigen-specific CD8(+) T cells.