Transduction and Utility of the Granulocyte-Macrophage Colony-Stimulating Factor Gene into Monocytes and Dendritic Cells by Adeno-Associated Virus

Abstract

The genetic manipulation of antigen-presenting dendritic cells (DC) offers promise for stimulating the immune response, in particular for anticancer and antiviral protocols. As adeno-associated virus (AAV) has shown promise as a gene delivery vector for transducing a variety of hematopoietic cell types, we have investigated AAV's ability to genetically alter DC. In this analysis, we modified the standard granulocytemacrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) treatment of adherent monocytes to generate DC. In our protocol, adherent monocytes were first infected with an AAV/GM-CSF/Neo vector, and the addition of IL-4 was delayed for 2 days to allow for a brief period of monocyte proliferation. AAV mediated transduction of the GM-CSF and Neo genes into monocytes/DC precursors was demonstrated by G418 selection, GM-CSF secretion, GM-CSF RNA expression (reverse transcriptase-polymerase chain reaction amplification [RT-PCR]), and cell proliferation. Cells resulting from infection with AAV/GM-CSF/Neo virus, and subsequent IL-4 and tumor necrosis factor- alpha (TNF-alpha) treatment, displayed multiple classic markers consistent with mature DC. Finally, chromosomal integration of the AAV vector was also demonstrated in sorted CD83+ DC. These data strongly suggest that AAV vectors will be useful for the genetic manipulation of DC and suggest that the transduction of the GM-CSF gene was able to fully replace the need for exogenous GM-CSF in the production of mature DC.