CD91 and its ligand gp96 confer cross-priming capabilities to multiple APCs during immune responses against nascent, emerging tumors

Expression of CD91 on DCs is essential in cross-priming of T cell responses in the context of nascent tumors. Multiple DC and macrophage subsets express CD91 and engage to initiate anti-tumor immune responses. The specific functions of CD91+ antigen presenting cells (APCs) that are required for T cell cross-priming during cancer immunosurveillance are still unknown. We used single cell RNA sequencing to analyze the the diversity and functions of various APCs in the tumor-draining lymph nodes at day 2 after tumor injection (D122 gp96EGFP+ tumor cells). APCs of CD91fl/fl x CD11cCre (KO) and wildtype littermates (WT) were isolated by fluorescence-activated cell sorting (FACS) according to the expression of CD11c and CD11b. Groups isolated for scRNAseq analysis are KO CD11c+ (SP) and CD11b+CD11c+ (DP), WT gp96-EGFP+ SP and DP and WT non-draining lymph node SP and DP.