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

Summary. 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 pp65495−503 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, pp65495−503‐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.