BACKGROUND:Dendritic cells (DCs) loaded with complex antigen are always used to induce cytotoxic T lymphocytes (CTLs) which have a speciifc anti-tumor activity. However, CTLs can assault autologous cells induced by DCs loaded with autologous antigen. This study aimed to explore how to weaken the autoimmune reaction induced by DC vaccine by combining mature DC (mDC) activating immunity and immature DC (imDC) leading to immune tolerance to make hepatocellular carcinoma (HCC) vaccine in vitro. METHODS: DC progenitors derived from human peripheral blood were assigned to two groups. One was cultured to mDC and pulsed with frozen-thawed antigen (FTA) of human HCC cell line SMMC-7721 cells (mDC group), and the other was cultured to imDC and pulsed with FTA of human liver cell line L-02 cells (imDC group). The morphology of DCs was monitored and cells phenotypes including HLA-DR, CD80, CD1α, CD83 were assayed by lfowcytometry (FCM). The concentrations of interleukin-12 (IL-12) in the supernatant were assayed by ELISA. Methyl thiazolyl tetrazolium (MTT) was used to evaluate T cell proliferation induced by mDC and imDC and the killing rate of CTL induced by mDC and imDC respectively/together on SMMC-7721 and L-02 cells. RESULTS: Compared with the imDC group, the mDC group was characterized by the following: increased secretion of IL-12 (P