Ex vivo stimulation of cytomegalovirus (CMV)-specific T cells using CMV pp65-modified dendritic cells as stimulators

Cytomegalovirus (CMV) infection is a dangerous complication in immunosuppressed individuals such as allogeneic stem cell transplant patients. CMV disease can be prevented by the early post-transplant transfer of donor-derived, CMV-directed, T cells. Fast and cost efficient methods to generate CMV-specific T cells are, therefore, warranted. The current study utilized peptide-pulsed and adenovirus-transduced dendritic cells (DC) to generate CMV-restricted T cells. After one stimulation with CMV pp65(495-503) peptide-pulsed DC and three re-stimulations with peptide-pulsed monocytes, virtually all T cells were CD8(+) , expressed the relevant T cell receptor and exhibited high peptide-specific lytic activity. After only one stimulation, pp65(495-503) -restricted T cells could be sorted to a purity of higher than 95% and expanded up to 1000-fold in 2 weeks. This technique may prove useful for the rapid generation of large quantities of specific cytolytic T lymphocytes (CTL) for cell therapy. DC transduced with an adenoviral vector encoding the full-length pp65 protein (Adpp65) were able to simultaneously expand CTL against multiple epitopes of pp65. In addition, they activated CMV-specific CD4(+) T-helper cells. This approach would stimulate multiple-epitope populations of pp65-specific T cells and could be made available to patients of any human leucocyte antigen (HLA) haplotype. DC transduced with adenoviral vectors to express full-length antigens may prove to be potent vaccines against viral pathogens and cancer.