Induction of carcinoembryonic antigen (CEA)-specific cytotoxic T-lymphocyte responses in vitro using autologous dendritic cells loaded with CEA peptide or CEA RNA in patients with metastatic malignancies expressing CEA

The application of dendritic cells (DC) to the active immunotherapy of canc er currently relies on the generation of potent DC capable of presenting tu mor antigens such as carcinoembryonic antigen (CEA), It is unknown whether the T cells of patients with advanced malignancies can be reliably stimulat ed against tumor antigens by their autologous DC. In this study, starting w ith the peripheral blood mononuclear cells (PBMC) of patients with metastat ic malignancies expressing CEA, autologous DCs were generated in vitro in s erum-free media supplemented with GM-CSF and IL-4, The DCs from HLA AZ posi tive patients were loaded with the CEA peptide CAP-I and the DCs from HLA A Z negative patients were depleted of bystander lymphocytes and loaded with mRNA encoding CEA, The DC preparations were tested to determine their pheno type and were used to stimulate autologous PBMC twice, separated by 10-14 d ays. The stimulated cells were then tested for their ability to lyse CEA-ex pressing target cells. We successfully generated an adequate number of DC f or a clinical trial from all patients. The harvested DC preparations contai ned 49% DC and 87% DC if depleted of bystander lymphocytes, Phenotypic anal ysis showed the typical pattern of CD11c(+)CD40(+)CD86(+)HLA-DR+ CD80(low)C D83(low)CD14(low). All preparations but one were able to stimulate CEA-spec ific cytotoxic T-lymphocyte (CTL) activity, suggesting that the majority of patients are not anergic to CEA and possess functional DC. The CTL activit y was similar for the CEA peptide and CEA RNA-loaded DC. (C) 1999 Wiley-Lis s, Inc.