OBJECTIVETo study the feasibility of transfecting breast cancer BA46 gene into dendritic cells (DCs) using adeno-associated virus (AAV) to induce specific cellular immunity.

METHODSMononuclear cells (DC precursor) were isolated from the peripheral blood of healthy donors by density gradient centrifugation and infected with rAAV/BA46/Neo virus stock (transfection group) or pulsed with 293 cell lysate (control group). In both groups, maturation of the DC precursor was induced by granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4) and tumor necrosis factor-alpha(TNF-alpha). On day 7, the DCs were collected and mixed with T cells at the ratio of 1 to 20 to induce cytotoxic T lymphocytes (CTL). The capacity of the DCs in stimulating T lymphocyte proliferation was assessed using (3)H-thymidine incorporation assay. The expressions of interferon-gamma (IFN-gamma), IL-4, CD4, CD8, CD25 and CD69 in the CTLs were analyzed with cytometry, and the cytotoxicity of the CTLs was evaluated with (51)Cr-release assay using BA46-positive breast cancer cell line Hs578T as the target.

RESULTSThe DCs transfected with BA46 gene exhibited potent capacity to stimulate T lymphocyte proliferation. The CTL population induced by the transfected DCs expressed high levels of CD8, CD69 and IFN-gamma, and showed strong cytotoxicity against BA46-positive breast cancer cell line Hs578T, which was BA46 antigen-specific and MHC-limited.

CONCLUSIONThe success in BA46 gene transfer in the DCs that induce specific cellular immunity provides the experimental basis for breast cancer immunotherapy using genetically modified cells.