Which cells kill virus-infected cells and tumor cells via perforin/granzyme pathways?

Which cells kill virus-infected cells and tumor cells via perforin/granzyme pathways?

• A. CD4+ helper T lymphocytes
• B. B lymphocytes
• C. Neutrophils
• D. CD8+ cytotoxic T lymphocytes (CTLs)

Answer: (D)

The main idea is how cytotoxic T lymphocytes kill abnormal cells directly. These CD8+ CTLs recognize small peptide antigens presented on MHC class I molecules on nearly all nucleated cells. When a CTL binds a cell displaying its specific antigen, it releases cytotoxic granules containing perforin and granzymes. Perforin forms pores in the target cell membrane, allowing granzymes to enter and activate caspases, which drive apoptosis of the infected or malignant cell. This targeted killing helps eliminate virus-infected cells and tumor cells while minimizing collateral damage to surrounding tissue. Other cell types listed don’t primarily kill via this perforin/granzyme mechanism: helper T cells coordinate responses, B cells produce antibodies, and neutrophils rely on phagocytosis and other antimicrobial methods.

The main idea is how cytotoxic T lymphocytes kill abnormal cells directly. These CD8+ CTLs recognize small peptide antigens presented on MHC class I molecules on nearly all nucleated cells. When a CTL binds a cell displaying its specific antigen, it releases cytotoxic granules containing perforin and granzymes. Perforin forms pores in the target cell membrane, allowing granzymes to enter and activate caspases, which drive apoptosis of the infected or malignant cell. This targeted killing helps eliminate virus-infected cells and tumor cells while minimizing collateral damage to surrounding tissue. Other cell types listed don’t primarily kill via this perforin/granzyme mechanism: helper T cells coordinate responses, B cells produce antibodies, and neutrophils rely on phagocytosis and other antimicrobial methods.