Which cell mediates cell-mediated immunity by attacking infected or cancerous cells?

Which cell mediates cell-mediated immunity by attacking infected or cancerous cells?

• A. T lymphocytes
• B. B lymphocytes
• C. Neutrophils
• D. Eosinophils

Answer: (A)

Cell-mediated immunity is carried out primarily by T lymphocytes. These cells recognize antigens presented by infected or transformed cells on MHC molecules and can directly kill those cells or coordinate other immune responses through cytokines. The cytotoxic subset (CD8+ T cells) binds target cells and releases perforin and granzymes to induce apoptosis in the infected or cancerous cell. Helper T cells (CD4+ T cells) assist by activating macrophages and supporting the overall cytotoxic response. In contrast, B lymphocytes produce antibodies and drive humoral immunity against extracellular pathogens, while neutrophils and eosinophils are more involved in innate defense and allergic/parasitic responses rather than specific cell-mediated killing. Thus, the cell type that mediates cell-mediated immunity by attacking infected or cancerous cells is T lymphocytes.

Cell-mediated immunity is carried out primarily by T lymphocytes. These cells recognize antigens presented by infected or transformed cells on MHC molecules and can directly kill those cells or coordinate other immune responses through cytokines. The cytotoxic subset (CD8+ T cells) binds target cells and releases perforin and granzymes to induce apoptosis in the infected or cancerous cell. Helper T cells (CD4+ T cells) assist by activating macrophages and supporting the overall cytotoxic response. In contrast, B lymphocytes produce antibodies and drive humoral immunity against extracellular pathogens, while neutrophils and eosinophils are more involved in innate defense and allergic/parasitic responses rather than specific cell-mediated killing. Thus, the cell type that mediates cell-mediated immunity by attacking infected or cancerous cells is T lymphocytes.