[Efficient gene delivery into dendritic cells by fiber-mutant adenovirus vectors]

Dendritic cells (DC) are professional antigen-presenting cells with a key function in the immune system as initiators of T-cell responses against microbial pathogens and tumors. Therefore, the immunization using DC loaded with tumor-associated antigens is potential to represent a powerful method of inducing anti-tumor immunity. Recent studies have demonstrated the usefulness of DC genetically modified by adenovirus vectors (Ad) to immunotherapy, while sufficient gene transduction into DC is required for high doses of Ad. Entry of Ad into target cells occurs by serial two steps: the binding of Ad-fiber knob to Coxsackie-adenovirus receptor (CAR) on the cell surface, and the subsequent interaction between Arg-Gly-Asp (RGD) motif located in Ad-penton base and alpha v-integrins. The reverse transcription-polymerase chain reaction analysis revealed that the relative resistance of DC to Ad-mediated gene transfer was due to the absence of CAR expression, and that DC expressed adequate alpha v-integrins. Therefore, we investigated whether fiber-mutant Ad (FM-Ad) containing the RGD sequence in the fiber knob can efficiently transduce and express high levels of the foreign gene into DC. The gene delivery by FM-Ad was more efficient than that by conventional Ad in both murine DC lines and normal human DC. Furthermore, both antigen presentations via major histocompatibility complex class I molecules and in vivo antigen-specific cytotoxic T lymphocyte induction by DC transduced with antigen gene by FM-Ad were superior to those by DC applied with conventional AD. We propose that alpha v-integrin-targeted FM-Ad is a very powerful tool to implement DC-based vaccination strategies.