Detailed analysis of cytomegalovirus (CMV)-specific T cells expanded for adoptive immunotherapy of CMV infection following allogeneic stem cell transplantation for malignant disease

BackgroundCytomegalovirus (CMV) infection and its treatment causes significant morbidity following allogeneic stem cell transplantation (SCT) for malignancies. We studied the phenotype, function and growth kinetics of CMV pp65 antigen (Ag)-specific T cells expanded in a short-term culture for adoptive therapy.MethodsPeripheral blood mononuclear cells (PBMC) from CMV-seropositive donors were cultured in various conditions with CMV pp65(495–503) peptide to determine the most effective method for generating CMV-specific T cells. CMV-expanded cultures were tested for frequency, phenotype and functionality using peptide–MHC tetramer analysis, cytokine flow cytometry and cytolytic assays. A patient undergoing allogeneic SCT was administered CMV pp65-specific T cells generated from the donor based on these data, and recipient PBMC were analyzed following T-cell infusion.ResultsCMV pp65-specific T cells were consistently generated from CMV-seropositive donors at high frequencies (20–40% of CD8+ T cells), secreted interferon-gamma (IFN-γ) in response to CMV peptide and had lytic activity against CMV peptide-expressing targets. Cultured CMV-specific T cells were infused into a SCT recipient without toxicity.DiscussionStimulating donor PBMC to generate functional, Ag-specific T cells for infusion into SCT recipients was accomplished consistently using readily available technology. We observed no toxicity in one patient receiving T cells and were able to monitor infused cells. These findings support further study of this approach as a prophylaxis against the risk of infection in patients receiving allogeneic transplantation from CMV-seropositive donors.