RETROVIRAL TRANSDUCTION OF HUMAN DENDRITIC CELLS WITH A TUMOR-ASSOCIATED ANTIGEN GENE

Dendritic cells (DCs) are potent antigen-presenting cells that can act ivate quiescent T lymphocytes. When pulsed with tumor-associated antig en (TAA) peptide or protein, murine DCs can provide antitumor immunity . me reasoned that DCs retrovirally transduced with TAA genes might ha ve important advantages over peptide- or protein-pulsed DCs, including long-term TAA presentation in pipe, and presentation of important but undefined epitopes. Therefore, we attempted to retrovirally transduce human DCs with a melanoma TAA gene (MART-1) and determine whether the se transduced DCs could raise a specific antitumor response from quies cent autologous T lymphocytes. After retroviral transduction, human CD 34(+) cells were differentiated into DCs in vitro using granulocyte ma crophage colony-stimulating factor, tumor necrosis factor alpha, and s tem cell factor, This method consistently yielded a population of DCs as analyzed by morphology phenotype, and MLR. Flow cytometric analysis revealed that 22-28% of cells expressing the DC phenotype also expres sed a transduced marker gene. When DCs were transduced with the gene e ncoding MART-1, they stimulated much higher levels of cytokine release by MART-1-specific tumor-infiltrating lymphocytes than control DCs tr ansduced with an irrelevant gene. In vitro stimulation using MART-1-tr ansduced DCs but not control-transduced DCs raised specific antitumor CTLs from autologous quiescent T cells. These results provide evidence that human DCs can be retrovirally transduced with a TAA gene and tha t these transduced cells can raise a specific antitumor immune respons e in vitro, Transduced DCs may be useful for in vivo immunization agai nst TAA.