On May 4, 2026, a study conducted by the University of Geneva and the Lausanne University Hospital (CHUV) report making it possible to visualize how Cytotoxic T lymphocytes, the body’s specialized “killer” cells, precisely eliminate infected or cancerous cells. Published in Cell Reports, the study reveals how the molecular organization of cytotoxic T cells underpins their function, opening new perspectives in immuno-oncology.

Cytotoxic T lymphocytes are the body’s specialized “killer” cells, precisely eliminating infected or cancerous cells. Their action relies on a specialized exchange zone called the “immune synapse,” where they release active molecules to destroy the target cell without damaging neighboring ones. Until now, the fine organization of these structures remained difficult to observe.

During infection or cancer, cytotoxic T lymphocytes attach to their target and establish an exchange zone known as the immune synapse, then release toxic molecules that trigger the death of the targeted cell. This mechanism enables precise and controlled destruction, essential for protecting the body while avoiding damage to nearby healthy cells.

Although this process has been widely studied, its organization at the nanometer scale in intact human cells remained difficult to access. One of the main obstacles lies in sample preparation methods, which can alter fragile cellular structures. Existing imaging approaches often involve trade-offs between resolution, observable volume, and preservation of structures.

By providing a three-dimensional and near-native view of these processes, this work establishes a reference framework for analyzing how immune cells function. It could help improve therapeutic strategies, particularly in immuno-oncology, by enabling a better understanding of the mechanisms that determine the effectiveness – or limitations – of the immune response.