Transduction of human dendritic cells with a recombinant modified vacciniaAnkara virus encoding MUC1 and IL-2

The epithelial mucin MUC1 is considered an opportune target antigen for can cer immunotherapy, as it is over-expressed and exhibits aberrant glycosylat ion in malignant cells. Because dendritic cells (DC) are powerful initiator s of immune responses, efforts have focused on tumor antigen-bearing DC as potent cancer vaccines. In this study we have characterized the transductio n of monocyte-derived DC with a highly attenuated vaccinia virus vector [mo dified vaccinia Ankara (MVA)] encoding human MUC1 and the immunostimulatory cytokine IL-2. Analysis of transduced DC cultures generated from a number of donors revealed MUC1 expression in the range of 27-54% of the cells and a co-regulated secretion of bioactive IL-2. As shown by FACS analysis with MUC1-specific antibodies, the MVA-MUC1/IL-2-transduced DC predominantly exp ressed the fully processed glycoform. of MUC1, typical of that displayed by normal epithelia. Over a 3-day period after transduction, transgene expres sion declined concurrent with an increase in MVA-induced cytopathic effects . The transduced DC stimulated allogeneic lymphocyte proliferation, indicat ing that DC immunostimulatory function is not impaired by vector transducti on. In the presence of IL-2, MVA-transduced DC were able to enhance autolog ous lymphocyte proliferation. Also, vector expression was analyzed in DC cu ltures treated with TNF-alpha, a known DC maturation factor. As indicated b y the up-regulation of several DC maturation markers, neither virus infecti on nor transgene expression influenced the maturation capacity of the cells . The MVA-MUC1/IL-2 vector effectively transduced both immature and TNF-alp ha -matured DC. Overall, our results are encouraging for the clinical appli cation of MVA-MUC1/IL-2-transduced DC.