The use of tumor antigen loaded dendritic cells (DC) is one of the most promising approaches to induce a tumor specific immune response in vivo. Several strategies have been designed to load DC with tumor antigens. In this study, we investigated the delivery of in vitro transcribed RNA and plasmid DNA into monocyte-derived, ie non-proliferating human DC, using several nonviral transfection methods including electroporation and lipofection. Green fluorescent protein (GFP) was used as a reporter gene and influenza matrix protein 1 (M1) as a model antigen for HLA class I restricted antigen presentation. Using electroporation in combination with DNA or with RNA, up to 11% of DC were GFP-positive. Using liposomes as a vehicle for DNA transport up to 10% of the DC were GFP-positive. A significant