Measuring in vitro induction of antigen-specific CD8⁺ T-cell responses by murine conventional dendritic cells

Type 1 conventional dendritic cells (cDC1s) play a central role in directing CD8⁺ T-cell responses. Mechanistic studies on cDC1-CD8⁺ T-cell communication are hindered by the scarcity of cDC1s and their inability to be propagated in vitro. Furthermore, dendritic cells derived from bone marrow or monocytes generally lack phenotypic and functional properties of ex vivo cDC1s. Here, we present a controlled in vitro CD8⁺ T-cell priming platform based on the isolation of ex vivo primary cDCs from spleens of B16-FLT3L tumor-bearing mice. This system enables read out of CD8⁺ T-cell proliferation and cytotoxic effector differentiation in response to debris from (tumor) cells that die by different modes of cell death. The set up can also be modified to include read outs for cDC status and phagocytic activity. Our approach establishes a reproducible and physiologically relevant method to study cDC-T-cell interactions in vitro, with broad applications in tumor immunology and vaccine development.