Modulation of antigen presentation by transfection of dendritic cells with GM-CSF

Effective antigen presentation by Dendritic cells (DC's) is crucial for induction of T-cell-mediated immune responses. For maintenance of in vitro viability and antigen presenting capacity, culture of DC's in GM-CSF is required. In an attempt to enhance the antigen presenting capacity and viability of DC's for potential in vivo experiments, we transfected in vitro Cultivated BALB/c bone marrow-derived DC's (> 70% purity) with GM-CSF (CMV promoter), using the adenovirus-transferrin-polylysin system, β-galactosidase was used as a reporter vector. The effectiveness of transfection was approximately 20%. At 24 hours, transfection with 3μg GM-CSF/10⁶ cells resulted in a viability of 60% and a GM-CSF production of 0,0017 U/cell. This correlated with the level of mRNA expression, as determined by RTPCR analysis. Upon evaluation at 8 days of cell culture in the absence of exogenous GM-CSF, viability of transfected DC's was similar to control cells incubated with 100 U/ml of exogenous GM-CSF and was increased by >7S% compared to mock transfected cells. Likewise, induction of allogeneic T-cell proliferation and presentation of peptide antigen by GM-CSF-transfected DC's was similar to that of DC's incubated in exogenous GM-CSF and was increased greatly when compared to rnock-transfected cells. These results suggest mat transfection of DC's with GM-CSF may have potential applications in the enhancement of immune responses.