A modified peptide stimulation method for efficient amplification of cytomegalovirus (CMV)-specific CTLs

CMV-specific immunity is essential for control of human cytomegalovirus (HCMV) infection. Stem cell transplantation is used widely in the management of a range of diseases of the hemopoietic system. Patients are immunosuppressed profoundly in the early posttransplant period, and reactivation of cytomegalovirus (CMV) remains a significant cause of morbidity and mortality. Adoptive transfer of CMV-specific CD8+ T cell clones has been shown to reduce the rate of viral reactivation; however, the ex vivo production of cells for adoptive transfer is labor intensive and expensive. We report here a modified peptide stimulation method using CMV-specific epitope peptides to stimulate PBMCs for generation of CMV-specific CTLs. This method permits efficient amplification of CMV-specific CTLs and provides a large number of cells for FACS analysis from a single blood sample. Significantly, it achieves high frequencies of tetramer staining of CD8+ T cells allowing the data of different individuals to be easily compared and sequentially evaluated. Thus, this approach expands and selects HLA-restricted CMV-pp65-reactive T-cell lines of high specificity for potential adoptive immunotherapy.