Direct transfection and activation of human cutaneous dendritic cells

Gene therapy techniques can be important tools for the induction and contro l of immune responses. Antigen delivery is a critical challenge in vaccine design, and DNA-based immunization offers an attractive method to deliver e ncoded transgenic protein antigens. In the present study, we used a gene gu n to transfect human skin organ cultures with a particular goal of expressi ng transgenic antigens in resident cutaneous dendritic cells. Our studies d emonstrate that when delivered to human skin, gold particles are observed p rimarily in the epidermis, even when high helium delivery pressures are use d. We demonstrate that Langerhans cells resident in the basal epidermis can be transfected, and that biolistic gene delivery is sufficient to stimulat e the activation and migration of skin dendritic cells. RT-PCR analysis of dendritic cells, which have migrated from transfected skin, demonstrates th e presence of transgenic mRNA, indicating direct transfection of cutaneous dendritic cells. Importantly, transfected epidermal Langerhans cells can ef ficiently present a peptide derived from the transgenic melanoma antigen MA RT-I to a MART-1-specific CTL. Taken together, our results demonstrate dire ct transfection, activation, and antigen-specific stimulatory function of i n situ transduced human Langerhans cells.