How do cytotoxic T lymphocytes kill target cells?

How do cytotoxic T lymphocytes kill target cells?

• A. They produce granzymes that stimulate apoptosis.
• B. They stop protein synthesis in the target cell.
• C. They engulf the cell by phagocytosis.
• D. They produce antibodies that bind to the cell.

Answer: (A)

Cytotoxic T lymphocytes kill target cells through granule-mediated cytotoxicity. When a CTL recognizes a target, it releases granules containing perforin and granzymes. Perforin forms pores in the target cell membrane, allowing granzymes to enter. Once inside, granzymes activate the caspase cascade, triggering apoptosis and leading to controlled death of the infected or malignant cell. This mechanism is why producing granzymes that induce apoptosis is the correct description. The other options don’t fit: stopping protein synthesis isn’t how CTLs principally kill (that’s a toxin effect in some contexts), phagocytosis is done by phagocytes like macrophages, and antibodies are produced by B cells, not CTLs.

Cytotoxic T lymphocytes kill target cells through granule-mediated cytotoxicity. When a CTL recognizes a target, it releases granules containing perforin and granzymes. Perforin forms pores in the target cell membrane, allowing granzymes to enter. Once inside, granzymes activate the caspase cascade, triggering apoptosis and leading to controlled death of the infected or malignant cell.

This mechanism is why producing granzymes that induce apoptosis is the correct description. The other options don’t fit: stopping protein synthesis isn’t how CTLs principally kill (that’s a toxin effect in some contexts), phagocytosis is done by phagocytes like macrophages, and antibodies are produced by B cells, not CTLs.