Type 2 dendritic cells mediate control of cytotoxic T cell resistant tumors

Type-2 dendritic cells (DC2s) comprise the majority of conventional DCs within most tumors; however, little is known about their ability to initiate and sustain anti-tumor immunity as most studies have focused on antigen cross-presenting Type-1 DCs (DC1s). Here we report that DC2 infiltration identified by analysis of multiple human cancer data sets showed a significant correlation with survival across multiple human cancers, with the benefit being seen in tumors resistant to cytotoxic T cell control. Characterization of DC subtype infiltration into an immunotherapy-resistant model of breast cancer revealed that impairment of DC1s through two unique models resulted in enhanced DC2 functionality and improved tumor control. Batf3-deficiency depleted intratumoral DC1s led to increased DC2 lymph node migration and CD4+ T cell activation. Enhancing DC2 stimulatory potential by genetic deletion of Hsp90b1 (encoding molecular chaperon GP96) led to a similar enhancement of T cell immunity and improved survival in a spontaneous breast cancer model. This data highlights the therapeutic and prognostic potential of DC2s within checkpoint blockade-resistant tumors.