A study led by researchers at the Centro Nacional de Investigaciones Cardiovasculares (CNIC) has identified a mitochondrial “checkpoint” that enables dendritic cells to efficiently activate T lymphocytes against viruses and tumors. Dendritic cells are immune cells that detect threats and activate the body’s defenses, acting as “sentinels” that instruct T lymphocytes on what to attack.

The study, published in Science Immunology, shows that restoring the internal chemical imbalance caused by defective mitochondrial function in dendritic cells restores the capacity of immune cells to defend the body against infection. The findings could open new avenues for improving cancer immunotherapy.

The study reveals that the ability of dendritic cells to activate T lymphocytes depends on an unexpected mechanism: the proper functioning of mitochondrial complex I, a key mitochondrial component. Mitochondrial complex I acts as a “metabolic switch” that is essential for the ability of dendritic cells to convert viral or tumor-derived material into effective immune activation signals and trigger a strong T-cell response.