AP BIOLOGY

Detailed explanation-1: -Cytotoxic CD8 T cells carry out their killing function by releasing two types of preformed cytotoxic protein: the granzymes, which seem able to induce apoptosis in any type of target cell, and the pore-forming protein perforin, which punches holes in the target-cell membrane through which the granzymes can enter.

Detailed explanation-2: -The microtubule-organizing centre (MTOC) of the cytotoxic lymphocyte polarizes and secretory granules traffic towards the presynaptic membrane (part b). The secretory granules then fuse with the presynaptic membrane and release perforin and granzymes into the synaptic cleft (parts c and d).

Detailed explanation-3: -Killer lymphocytes use granulysin, perforin and granzymes to kill intracellular parasites. Nat Med. 2016 Feb; 22(2):210-6. doi: 10.1038/nm.

Detailed explanation-4: -Perforin/granzyme-induced apoptosis is the main pathway used by cytotoxic lymphocytes to eliminate virus-infected or transformed cells. Studies in gene-disrupted mice indicate that perforin is vital for cytotoxic effector function; it has an indispensable, but undefined, role in granzyme-mediated apoptosis.