Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells are key immune effectors that eradicate infected cells and tumor cells. To destroy these targets, CTL and NK cells mostly use the granule exocytosis pathway which releases perforin and granzymes from cytolytic granules into the immunological synapse formed with the target. Granzyme A and granzyme B, the most abundant granzymes, are delivered to the target cell cytosol through perforin and independently induce cell death. The tryptase granzyme A activates cell death through a caspase-independent mechanism. Granzyme A causes characteristic features of apoptosis, including membrane blebbing, loss of mitochondrial transmembrane potential, nuclear fragmentation and chromatin condensation...