Dendritic cells engineered to secrete anti-Dc R3 antibody augment cytotoxic T lymphocyte response against pancreatic cancer in vitro

摘要

AIM To investigate the enhanced cytotoxic T lymphocyte responses against pancreatic cancer(PC) in vitro induced by dendritic cells(DCs) engineered to secrete anti-DcR 3 monoclonal antibody(mA b).METHODS DCs, T lymphocytes and primary PC cells were obtained from PC patients. DCs were transfected with a designed humanized anti-Dc R3 monoclonal antibody heavy and light chain m RNA and/or total tumor RNA(DC-tumor-anti-Dc R3 RNA or DC-total tumor RNA) by using electroporation technology. The identification, concentration and function of anti-DcR 3 mA b secreted by DC-tumor-anti-Dc R3 RNA were determined by western blotting and enzyme-linked immunosorbent assay. After co-culturing of autologous isolated PC cells with target DCs, the effects of secreting anti-DcR 3 mA b on RNA-DCs' viability and apoptosis were assessed by MTT assay and flow cytometry. Analysis of enhanced antigen-specific immune response against PC induced by anti-DcR 3 mA b secreting DCs was performed using a 51 Cr releasing test. T cell responses induced by RNAloaded DCs were analyzed by measuring cytokine levels, including IFN-γ, IL-10, IL4, TNF-α and IL-12.RESULTS The anti-Dc R3 m Ab secreted by DCs reacted withrecombinant human Dc R3 protein and generated a band with 35 k Da molecular weight. The secreting m Ab was transient, peaking at 24 h and becoming undetectable after 72 h. After co-incubation with DCtumor-anti-Dc R3 RNA for designated times, the Dc R3 level in the supernatant of autologous PC cells was significantly down-regulated(P < 0.05). DCs secreting anti-Dc R3 m Ab could improve cell viability and slow down the apoptosis of RNA-loaded DCs, compared with DC-total tumor RNA(P < 0.01). The anti-Dc R3 m Ab secreted by DC-tumor-anti-Dc R3 RNA could enhance the induction of cytotoxic T lymphocytes(CTLs) activity toward RNA-transfected DCs, primary tumor cells, and PC cell lines, compared with CTLs stimulated by DC-total tumor RNA or control group(P < 0.05). Meanwhile, the antigen-specific CTL responses were MHC class I-restricted. The CD4+ T cells and CD8+ T cells incubated with anti-DcR 3 mA b secreting DCs could produce extremely higher level IFN-γ and lower level IL4 than those incubated with DC-total tumor RNA or controls(P < 0.01).CONCLUSION DCs engineered to secrete anti-Dc R3 antibody can augment CTL responses against PC in vitro, and the immune-enhancing effects may be partly due to their capability of down-regulating DC apoptosis and adjusting the Th1/Th2 cytokine network.