OBJECTIVETo investigate the specific anti-breast cancer immune response induced by dendritic cells (DC) loaded with trastuzumab and apoptotic Her-2+ breast cancer cells.

METHODSDCs were generated from healthy peripheral blood mononuclear cells (PBMCs) in the presence of recombinant cytokines GM-CSF, IL-4 and TNF-alpha. Mature DCs were harvested after 7 days' co-culture of PBMCs and trastuzumab-treated apoptotic SKBr3 cells. The morphologic characteristics and ultrastructure of the DC were observed under the inverted phase-contrast microscope and transmission electron microscope (TEM), respectively. Flow cytometry (FCM) was used to check the expression of several DC specific markers: CD14, CD1a, CD64, CD80, CD83, CD86, HLA-ABC and HLA-DR. DC-cytokine induced killer (DC-CIK) cells were prepared by co-culture of DCs and peripheral blood lymphocytes in the presence of anti-CD3 antibodies and human IL-2 at an appropriate concentration. The number of antigen-specific T cells was analyzed by human interferon gamma enzyme linked immunospot (ELISPOT) assay. MTT assay was employed to assess the lysis of breast cancer cell line induced by DC-CIK cells.

RESULTS5 minutes after the adding of DCs to SKBr3 cells pretreated with trastuzumab, the apoptotic SKBr3 cells were found to be circled by DCs. 48 hours later, many membrane-wrapped organelles of the apoptotic target cells in the cytoplasm of DCs were found by TEM. The majority of the organelles were degraded. Fewer organelles from the apoptotic cells were found in DCs without Herceptin. More than 60% in every group of DCs expressed a high-affinity receptor for IgG (FcgammaRI or CD64). CD14 expression on the mature DCs were comparatively lower, and HLA-DR and HLA-ABC expressions were higher in the trastuzumab group. The expression of CD1a, CD80, CD83 and CD86 in trastuzumab group were higher than those in immature DCs group (P < 0.05). ELISPOT assay suggests that the spot number of antigen-specific T cells were higher in trastuzumab group than that in the antigen unloaded DCs group (P < 0.05). The lysis of SKBr3 cells induced by the SKBr3 antigen loaded DC-CIK cells were 1.7 times higher than that of CIK.

CONCLUSIONThe lysis of SKBr3 cells induced by DC-CIK was increased after that DCs were combined with trastuzumab to capture antigen from SKBr3 cells. These findings support further investigation into the use of combination immunotherapy of the humanized monoclonal antibody, DC vaccines and immunological effector cells.