OBJECTIVETo investigate the anti-gastric carcinoma immunological efficacy of dendritic cells (DC) precursors, that were mobilized into the peripheral blood by injection of macrophage inflammation protein-1 alpha (MIP-1 alpha), and induced by DC vaccine expressing melanoma antigen gene-3 (MAGE-3) ex vivo and in vivo.

METHODS615 mice were injected with MIP-1 alpha via the tail vein. Freshly isolated B220(-) CD11c+ cells were cultured with cytokines and assayed by phenotype analysis and mixed lymphocyte reaction (MLR). For adenoviral (Ad)-mediated gene transduction, cultured B220(-) CD11c+ cells were incubated with Ad-melanoma antigen gene-3. MIP-1 alpha-mobilized B220(-) CD11c+ cells pulsed MFC cells tumor lysate were used as positive control. The stimulated DC vaccination-induced T lymphocytes, and the killing effect of the T cells on gastric carcinoma cells were assayed by MTT. INF-gamma production was determined with the INF-gamma ELISA kit. To establish the solid tumor model, groups of 615 mice were injected with MFC cells subcutaneously into the abdominal wall. MIP-1 alpha-mobilized DC vaccines expressing MAGE-3 gene were used to immunize the mice after the challenge of MFC cells, then the tumor size and the survival of mice were examined to detect the therapeutic effect of DC vaccines.

RESULTSB220(-) CD11c+ cells increased obviously after MIP-1 alpha injection, and freshly isolated B220(-) CD11c+ cells cultured with mGM-CSF, IL-4, and mTNF-alpha were phenotypically identical to typical DC, gained the capacity to stimulate allogeneic T cells. These MIP-1 alpha-mobilized DCs were transduced with Ad-MAGE-3, which were prepared for DC vaccines expressing tumor antigen. T lymphocytes stimulated with DC-transduced with Ad-MAGE-3 showed specific killing effect on gastric carcinoma cells and produced high levels of INF-gamma [(1460.00 +/- 16.82) pg/ml]. Five days after the MFC cells challenge, the mice were subsequently injected with DC vaccines. The tumor size of the experimental group was significantly smaller than that in the positive control group and the negative control groups (P<0.01). Kaplan-Meier survival curves showed the survival of the experimental group mice was significantly longer than that of the control groups (P<0.01).

CONCLUSIONB220(-) CD11c+ DC precursors are rapidly accumulated in the peripheral blood after injection of MIP-1 alpha into mice, which can further differentiate into mature DCs. These MIP-1 alpha-mobilized DCs, when transduced with MAGE-3 gene, can induce specific CTL to gastric carcinoma cells ex vivo, and can generate anti-tumor therapeutic effects on MFC cells loading mice in vivo. The efficiency of anti-tumor therapeutic immunity induced by MIP-1 alpha-mobilized DCs expressing tumor antigen are much more potent than MIP-1 alpha mobilized DCs pulsed MFC cells tumor lysate.