Background Objective evaluation of the antitumor effect of interleukin-12 (IL-12) gene-transfected dendritic cell (DC)vaccine on laryngeal carcinoma requires in vivo and in vitro tests. The aim of this study was to investigate the function of IL-12 gene transfected DC at initiating specific immune response to laryngeal carcinoma in vitro.Methods Recombinant adenovirus with IL-12 gene was constructed. DCs were isolated from the peripheral blood of patients with laryngeal carcinoma, pulsed with tumor lysate of laryngeal carcinoma cells (DC+Ag), and transfected with IL-12 (DC-IL-12+Ag). The cells pheotypes including CD83, CD86 and HLA-DR on surface of DCs were assayed by flow cytometry (FCM). The concentration of IL-12 in culture supatant of DCs and interferon γ (IFN-γ) in culture supatant of T cells cocultured with DCs were quantified by ELISA. Methyl thiazolys tetrazolium (MTT) was used to evaluate proliferation of autologous T lymphocytes and activation of cytotoxic T lymphocytes (CTL) stimulated by IL-12-transfected DCs pulsed with tumor lysate against laryngeal carcinoma cells.Results The recombinant adenovirus expressing IL-12 gene was constructed successfully. Gene-transfected DC plused with tumor lysate with IL-12 (DC-IL-12+Ag) expressed higher level of CD83, CD86 and produced higher level of IL-12 than untransfected DCs (DC+Ag) (CD83: (60.2±1.8)% vs. (50.7±1.2)%, P ＜0.05; CD86: (88.9±2.1)% vs.(78.2±3.9)%, P ＜0.05; IL-12: (262.5±3.0) ng/L vs. (103.8±5.1) ng/L, P ＜0.05). The proliferation of autologous T lymphocytes and production of IFN-γ stimulated by DC transfected with IL-12 were more obviously than untransfected DCs. Cytotoxicity of CTL stimulated by IL-12-transfected DC pulsed with tumor lysate against laryngeal carcinoma cells were significantly stronger than stimulated by untransfected DC.Conclusion It is a promising approach for IL-12-transfected DC pulsed with tumor lysate to increase the antitumoral effect.