Objective: To investigate the antitumor activity of tumor lysate-pulsed dendritic cells vaccine in RM-1 prostate cancer mice model with the survival time of mice calculated and the tumor size measured in DC vaccine therapy. Methods: C57BL/6 mice were immunized on the dorsal flank by s.c. inoculation of Lysate-DC

ova-DC

and non-DC on day -7. On day 0

2×106cells of RM-1 tumor cells （H-2b） were injected s.c. in C57BL/6 mice pre-treated by s.c. inoculation of modified DCs

correspondingly. DTH assay was performed with modified DCs. In partial test

for the determination of which immune cells were required for antitumor activity

mice were immunodepleted of CD4

CD8

or natural killer （NK） NK1.1 cells with the corresponding monoclonal antibodies. The survival time of nude mice loaded with tumor cells was calculated and the size of tumor measured. Results: In RM-1 mice prostate cancer model

immunized with lysate-DC

compared with ova-DC and non-DC

the pre-infection vaccine resulted in 100% clearance of primary tumors

whereas on day 0 of injection vaccine cleared 40-60% of primary tumors. On day 0

C57BL/6 mice （H-2b） were immunized with Lysate-DC

compared with ova-DC and non-DC by caudal vein injection

then on day 15

RM-1 cells were inoculated. On day 30

average diameters of tumor in different groups of modified DC were 23.7±5.4 mm

22.1±4.9 mm

4.3±2.6 mm

respectively. Lysate-DC

compared with ova-DC and non-DC

can greatly depressed RM-1 tumor cell growth （P<0.01）. The mean survival time of C57BL/6 mice in Lysate-DC

ova-DC and non-DC groups were 15.8±2.6

16.6±3.2

39.0±5.6

respectively

and there was a significant difference in the mean survival time in lysate-DC group between ova-DC and non-DC group （P<0.01）. DTH test showed that lysate-DC could prime T lymphocyte and elicit tumor antigen specific immune response

and over 80% mice in groups of lysate-DC showed obvious swelling in their foot pad. This response was strengthened with repeating inoculation

whereas DTH response was not seen in control group. In vivo depletion of NK cells resulted in a 40-60% reduction in growth suppression within the primary tumor

and depletion of CD4+ cells resulted in a 20% reduction in growth suppression. Conclusion: The tumor lysate-pulsed dendritic cells vaccine could elicit antitumor activity in RM-1 loaded C57BL/6 mice

and prolong the duration of RM-1 loaded C57BL/6 mice. So DC-based immunotherapy with hormone-refractory prostate carcinoma yielded protective immunity

generated efficient cellular antitumor responses

thereby providing further preclinical support for feasible immunotherapy approaches for prostate cancer.