Cytotoxic T lymphocytes (CTLs) eliminate virus-infected tumor cells or alloantigen through a lyric mechanism, which involves the secretion of a cytoplasmic granules containing cytotoxic proteins, perforin and granzymes, of which the two most important are granzyme A and granzyme B. Perforin interacts with cell membranes and allows the access of granzymes into the target cell, inducing cell death by apoptosis. (more...)