Abstract: ObjectiveTo study the in vitro antitumor activity of dendritic cells (DCs) loading with antigen produced by radiofrequency ablation of tumor lysate in situ combined with cytokineinduced killer cells (CIK).MethodsCIK cells derived from BALB/C mouse spleen and DCs derived from bone marrow were prepared, and experimental model of murine colon carcinoma were established for radiofrequency ablation. The supernatant of tumor tissue in situ lysis after repeated freezing and thawing were tested by lowry protein quantitative statutory, amounting to a final concentration of 5 μg/ml, then load to the first 5 days of culture DCs (AgDC), 2 days later, cocultured with CIK cells after the first seven days of culture 48 h (AgDCCIK). Flow cytometry was used to analyze costimulatory molecules on the surface of the cells, and CCK8 assay to detect in vitro cytotoxic activity.ResultsThe DCs loading with antigen resulted in an increase in the proportion of CD86+CD11c+, MHCⅡ+CD11c+ and MHCⅡ+CD80+ cells .The main effector cells of CIK cells were CD3+ NK1.1+cells.The percentage of CD3+NK1.1+ cells was 1.45% on the first day of the culture；while when they had been cultured for 7 days, the percentage CD3+NK1.1+ significantly increased to 36.9%. The cytotoxicity of AgDCCIK cells toward C26 cells was much more efficient than that of DCCIK, CIK cells.The cytotoxic activity of the former was significantly lower than the latter and the same target ratio. When the ratios of effector cells to target cells were 5∶1, the cytotoxic activity of AgDCCIK cells against C26 cells was (74.9±3.5)%,; while the DCCIK was (71.2±2.1)% and the CIK cells was (68.7±2.9)%.The difference was statistically significant(F=7.007，P=0.007).When the ratios of effector cells to target cells were 10∶1, the cytotoxic activity of AgDCCIK cells against C26 cells was (82.3±4.5)%, while the DCCIK cells was (77.1±5.1)%, and the CIK cells was (72.7±2.8)%. The difference was statistically significant(F=7.727，P=0.005). When the ratios of effector cells to target cells were 20∶1, the cytotoxic activity of AgDCCIK cells against C26 cells was (83.2±1.9) %, while the DCCIK cells was (77.2±4.2)%, and the CIK cells was (73.0±2.6)%.The difference was statistically significant(F=16.594，P=0.000).ConclusionDCs loading with antigen produced by radiofrequency ablation of tumor in situ pyrolysis products can improve in vitro cytotoxic activity combined with CIK cells, which can provide a new comprehensive cancer treatment strategy.

Key words: Dendritic cells, Colonic neoplasms, Radiofrequency ablation