Calcium nanoparticles target and activate T cells to enhance anti-tumor function

Calcium signaling plays a crucial role in the activation of T lymphocytes. However, modulating calcium levels to control T cell activation in vivo remains a challenge. In this study, we investigate T cell activation using 12-myristate 13-acetate (PMA)-encapsulated CaCO₃ nanoparticles. We find that anti-PD-1 antibody-conjugated CaCO₃ nanoparticles can be internalized by T cells via receptor-mediated endocytosis and then gradually release calcium. This results in an increase in cytosolic calcium, which triggers the activation of NFAT and NF-κB pathways, especially when the surface of the CaCO₃ nanoparticles is loaded with PMA. Animal studies demonstrate that the PMA-loaded calcium nanoparticles enhance the activation and proliferation of cytotoxic T cells, leading to improved tumor suppression without additional toxicity. When tested in metastatic tumor models, T cells loaded with the calcium nanoparticles prior to adoptive cell transfer control tumor growth better, resulting in prolonged animal survival. Our approach offers an alternative T cell activation strategy to potentiate immunotherapy by targeting a fundamental signaling pathway.