Cytotoxic T lymphocytes serve as the immune system’s specialized “killer” cells, targeting and eliminating infected or cancerous cells with remarkable accuracy. Their effectiveness depends on a tightly controlled contact point known as the “immune synapse,” where they release toxic molecules that destroy the target while leaving nearby healthy cells unharmed. Until recently, scientists could not clearly observe how these structures are organized.

Researchers at the University of Geneva (UNIGE) and the Lausanne University Hospital (CHUV) have now visualized these processes in three dimensions while preserving conditions close to their natural state. Their findings, published in Cell Reports, show how the internal organization of cytotoxic T cells supports their function and point to new possibilities in immuno-oncology.

How Killer T Cells Precisely Eliminate Threats
When the body encounters infection or cancer, cytotoxic T lymphocytes attach to the affected cell and form the immune synapse. Through this interface, they release toxic compounds that trigger the death of the target cell. This highly controlled process allows the immune system to remove harmful cells without damaging surrounding tissue.

Although the overall mechanism is well known, studying its fine structure at the nanometer scale inside intact human cells has been difficult. One major challenge comes from sample preparation, which can distort delicate cellular features. Traditional imaging methods often require compromises between resolution, the size of the area observed, and the preservation of natural structures.