Abstract: Objective To investigate the effects of wet hyperthermia combined with microwave ablation on the proportion and function of CD4+CD25+ regulatory T cell in animal model of mouse mammary carcinoma and explore its significance. Methods An experimental animal model of mouse mammary carcinoma was established and then treated with microwave ablation on day 14. Local wet hyperthermia was also performed. The proportion of CD4+ CD25+ regulatory T cells (Tregs) in splenocytes were analyzed by FACS. The relative expression of Foxp3, as well as the expression of CTLA4 and GITR, on Tregs was determined by Real-time PCR assay and FACS respectively. Moreover, the secretion of TGF-? and IL-10 from Tregs also were detected by ELISA. In addition, the suppressive capacity of Tregs on CD4+CD25-T cell also was performed by MTT assay. Results The proportion of Tregs in wet hyperthermia combined with microwave ablation treated group decreased significantly compared with that in wet hyperthermia or microwave ablation treated alone group (p<0.05). Moreover, the expression level of Foxp3 on Tregs decreased significantly (p<0.05). Furthermore, the expression of CTLA4 and GITR, as well as the secretion of TGF-? and IL-10, on Tregs also decreased obviously (p<0.05). Finally, the suppressive capacity of Tregs on the proliferation of CD4+CD25-T cells were also impaired significantly (p<0.05). Conclusions Wet hyperthermia combined with microwave ablation were more effective than single wet hyperthermia or microwave ablation on the function of Tregs, which may be closely related to the enhanced suppression of tumor growth.

Key words: Breast cancer, Microwave ablation, Wet hyperthermia, CD4+CD25+ regulatory T cells