OBJECTIVETo investigate the antitumor immune response induced by dendritic cells vaccine coding AFPcDNA fragment with signal peptide (AFP(1)) and without signal peptide (AFP(2)), and to determine the inhibiting effect of the vaccine on the growth of hepatocarcinoma xenograft in Balb/c mice.

METHODSpcDNA3.1/AFP(1) and pcDNA3.1/AFP(2) were transfected into dendritic cells (DCs) by calcium phosphate nanoparticles and became DCs vaccine. Mouse spleen lymphocytes were stimulated by AFP(1)/DC and AFP(2)/DC. A Balb/c mouse model bearing mouse HCC xenograft was established on the day 14 after transplantation. Forty mice were divided equally into AFP(2)/DC group, AFP(1)/DC group and plasmid control group. The treated mice received DCs vaccine and the same amount of control plasmid.

RESULTSAFP(2)/DC stimulated T lymphocytel proliferation in vitro and improved CTL activity. The effects were better than AFP(1)/DC. The tumor-bearing mice injected intralesionally with AFP(1)/DC and AFP(2)/DC at a dose of 0.5 ml per mouse showed inhibition of tumor growth and prolongation of survival time. The tumor inhibition rate of the AFP(2)/DC group was 79.2% and the AFP(1)/DC group was 39.7% at 2 weeks after treatment. The tumor volume of AFP(2)/DC group was (726.7 +/- 298.2) mm(3), significantly smaller than the (1486.2 +/- 457.2) mm(3) of the AFP(1)/DC group and (2137.2 +/- 547.2) mm(3) of the plasmid control group (P < 0.05). The mean survival time of mice in the AFP(2)/DC group [(58.5 +/- 4.2) d] and AFP(1)/DC group [(45.2 +/- 4.8) d] were significantly longer than that of plasmid control group [(30.6 +/- 6.2) d, P < 0.05]. Bax-positive cell percentage was increased in the xenografts of AFP(2)/DC-treatment group compare with that of plasmid control group.

CONCLUSIONAFP(2)/DC and AFP(1)/DC vaccines show evident inhibiting effect on the growth of H22 xenograft in Balb/c mice through inducing efficient and specific immune response against the hepatocarcinoma cells.