In Vitro Maturation of Bone Marrow-Derived Dendritic Cells via STING Activation for T Cell Priming

Dendritic cells (DCs) are the most potent antigen-presenting cells, serving as a bridge between innate and adaptive immunity. Activation of the stimulator of interferon genes (STING) pathway by pathogen-derived DNA induces type I interferon responses and promotes CD8⁺ cytotoxic T cell activity. This study aimed to establish a protocol for generating immature DCs from murine bone marrow, optimize their maturation in vitro with a STING agonist, and evaluate their ability to prime naïve T cells for potential use in cancer immunotherapy.

Bone marrow cells from C57BL/6 mice were differentiated into immature DCs under growth factor-supplemented conditions. Maturation was induced using a STING agonist and B16 tumor-derived DNA. Naïve CD4⁺ and CD8⁺ T cells were isolated via magnetic-activated cell sorting (MACS) and co-cultured with the stimulated DCs. Culture conditions were optimized to enhance DC maturation efficiency, and T cell proliferation was assessed following co-culture.

Optimization of the culture system markedly increased the yield of mature DCs. Importantly, co-culture of STING agonist-stimulated DCs with naïve T cells resulted in strong CD8⁺ T cell proliferation, indicating effective priming.

These findings demonstrate the feasibility of generating functional DCs in vitro and highlight their capacity to prime T cells through STING pathway activation. This proof-of-concept supports the development of DC-based platforms as a promising strategy for novel cancer immunotherapies.