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

ABSTRACT

BACKGROUND: Cytomegalovirus (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. METHODS: Peripheral 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. RESULTS: CMV pp65-specific T cells were consistently generated from CMV-seropositive donors at high frequencies (20-40% of CD8+ T cells), secreted interferon-gamma (IFN-gamma) 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. DISCUSSION: Stimulating 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.