Recombinant adenovirus is an efficient and non-perturbing genetic vector for human dendritic cells

Recombinant adenoviral vectors have promise for human gene therapy because of efficient transgene expression in nondividing primary cell types. Dendritic cells (DC) have potential as adjuvants for immune therapy, since they are specialized to capture antigens to form MHC-peptide complexes, migrate to T cell areas in the lymph node, and activate T cells including CD4+ helpers and CD8+ cytotoxic T lymphocytes (CTL). We show that several current chemical and physical transfection methods allow < 2 % of DC to express reporter genes but that recombinant adenoviruses, encoding the reporter genes green fluorescent protein and LacZ, efficiently transfect monocyte-derived human DC. Immature DC, generated with IL-4 and GM-CSF, are transfected to 95% efficiency, while mature DC show reduced transfection (50%) and gene expression. Adenovirus-transfected, immature DC exhibit several critical functions. The DC can differentiate in the presence of lipopolysaccharide or a monocyte-conditioned medium to express the surface markers of mature, T cell stimulatory DC including CD25, CD83, and high levels of CD86 and HLA-DR. Transfected DC can also secrete high levels of IL-12 and are potent inducers of T cell growth. Transgene expression in DC is stable for at least 6 days in the presence of the DC survival factor, TRANCE. Therefore adenoviral infection does not perturb the maturation and function of DC. The efficiency of adenoviral-mediated gene transfer prompts the evaluation of this vector in studies of DC biology, including the expression of antigens for active immune therapy.