Abstract
Recent studies suggest that highly activated, polyfunctional CD4+ T cells are incredibly effective in strengthening and sustaining overall host antitumor immunity, promoting tumor-specific CD4+ T-cell responses and effectively enhancing antitumor immunity by immunotherapy. Previously, we developed a novel cryo-thermal therapy for local tumor ablation and achieved long-term survival rates in several tumor models. It was discovered that cryo-thermal therapy remodeled the tumor microenvironment and induced an antigen-specific CD4+ T-cell response, which mediated stronger antitumor immunity in vivo. In this study, the phenotype of bulk T cells in spleen was analyzed by flow cytometry after cryo-thermal therapy and both CD4+ Th1 and CD8+ CTL were activated. In addition, by using T-cell depletion, isolation, and adoptive T-cell therapy, it was found that cryo-thermal therapy induced Th1-dominant CD4+ T cells that directly inhibited the growth of tumor cells, promoted the maturation of MDSCs via CD4+ T-cell-derived IFN-γ and enhanced the cytotoxic effector function of NK cells and CD8+ T cells, and promoted the maturation of APCs via cell-cell contact and CD4+ T-cell-derived IFN-γ. Considering the multiple roles of cryo-thermal-induced Th1-dominant CD4+ T cells in augmenting antitumor immune memory, we suggest that local cryo-thermal therapy is an attractive thermo-immunotherapy strategy to harness host antitumor immunity and has great potential for clinical application.