OBJECTIVETo investigate the therapeutic and immunological effects of microwave ablation (MA) combined with CpG ODN in mice bearing transplanted colon carcinoma.

METHODSA mouse model bearing colon carcinoma was established by subcutaneously inoculating CT26 cells into the right flank of Balb/c mice. The tumor-bearing mice were randomized into control group with PBS injection in the peritumoral area, MA group, MA combinated with CpG ODN group, and CpG ODN group with CpG ODN injection in the peritumoral area. The tumor volume changes were observed, and serum CD3(+)CD4(+) and CD3(+)CD8(+) T lmyphocytes were analyzed by flow cytometry after the treatments. Serum levels of interleukin (IL)-2, IL-12 and IFN-gamma were detected by ELISA. The mice in the MA group and the combined treatment group showing tumor regression were rechallenged with CT26 cells.

RESULTSNo significant difference was found in the number of serum CD3(+), CD3(+)CD4(+), or CD3(+)CD8(+) T lymphocytes between the 4 groups. The ratio of CD3(+)CD4(+)/CD3(+)CD8(+) T lymphocytes in the combined treatment group and MA group were 1.58-/+0.10 and 1.53-/+0.13, respectively, significantly higher than that in PBS group and CpG ODN group (P<0.05). The serum concentration of IL-2, IL-12 and IFN-gamma in the combined treatment group were 64.6-/+7.4 pg/ml, 314.1-/+26.9 pg/ml and 61.9-/+7.3 pg/ml, respectively, significantly higher than those in the other 3 groups (P<0.05). The tumor formation rate in the combined treatment group was significantly lower than that in MA group (25.0% vs 75.0%, P<0.05).

CONCLUSIONCpG ODN can enhance the immunity and decrease the tumor formation rate following a rechallenge with CT26 cells in mice treated with MA.