Anti-tumor Immune Response after Cryoablation in Renal Cell Carcinoma Murine Model

ABSTRACT

PURPOSE: Cryoablation has been used successfully for the local treatment of renal cell carcinoma. Besides local destruction, Cryoablation has an immunogenic nature. In this study, we evaluated the anti-tumor immune response induced by cryoablation in renal cell carcinoma murine model. MATERIALS AND METHODS: Renal cell carcinoma was produced in BALB/c mice by the subcutaneous inoculation of Renca cells in the thigh. After 7 days, the tumors were removed using liquid nitrogen in cryoablation group and bipolar electrocoagulation in electrocautery group. For twelve days after re-inoculation of Renca cells at contralateral thigh, tumor volumes were measured daily to assess the effect against the growth of tumor. The immunocyte levels (T4, T8, B and NK cell) were determined to evaluate immune activity by FACS (Fluorescence activated cell sorter) analysis. The effect of cryoablation to induce apoptosis of tumor was evaluated by TUNEL (Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end-labeling) assay. RESULTS: The tumor volume of cryoablation group was significantly smaller than that of electrocautery group and control (p<0.05). Comparing with control, T cell level was significantly increased after cryoablation (p<0.05), but no group had a significant difference in the levels of B cell and NK cell by FACS analysis. The apoptosis index % of cryoablation group was significantly increased than that of control group (p<0.05) by TUNEL. CONCLUSIONS: Cryoablation could result in the inhibition of re-inoculated tumor growth and induce T cell mediated immune response. The active immune response may be attributed to the apoptosis of tumor after cryoablation.