Generation of anti-p53 cytotoxic T lymphocytes from human peripheral blood using autologous dendritic cells

CTLs recognizing the HLA-A2.1-restricted, wild-type sequence p53 epitopes p53(149-157) and p53(264-272) were generated from CDS-enriched populations of nonadherent peripheral blood lymphocytes (PBLs) obtained from healthy donors. The PBLs were restimulated in vitro with peptide-pulsed granulocyte macrophage colony-stimulating factor- and interleukin (TL) il-induced autologous dendritic cells in the presence of IL-6 and IL-12 and subsequently cultivated with IL-1 alpha, IL-2, IL-4, IL-6, and IL-7. Bulk anti-p53(264-272) CTL populations were generated from PBLs obtained from two of five donors. Both CTL populations were cytotoxic against peptide-pulsed HLA-A2(+) target cells, but not against untreated target cells. A CD8(+) anti-p53 CTL clone designated p264#2 was isolated from one of the bulk populations. It was found to have an intermediate affinity of approximately 10(-9) M for the epitope and to mediate cytotoxicity against several human tumor cell lines, including the squamous cell carcinoma of the head and neck cell line SCC-9, which is known to present the wild-type sequence p53(264-272) epitope, In addition, CTLs reactive against p53(149-157)-pulsed targets as well as a HLA-A2(+) tumor cell line were cloned from a bulk population of antitumor CTLs obtained from one of the five normal PBLs restimulated with this epitope, The results indicate that CTLs recognizing wild-type sequence epitopes can be generated from precursors present in PBLs obtained from some normal individuals using autologous dendritic cells as antigen-presenting cells and suggest that vaccine strategies targeting these epitopes can lead to antitumor CTL generation, thereby emphasizing the therapeutic potential of p53-based cancer vaccines.