Reduced levels of ______ cytotoxicity have been found in people who are highly stressed:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Natural Killer Cell
Natural killer cells are white blood cells that are involved in the fight against both viruses and tumours. Stress affects natural killer cell cytotoxicity, which is of major importance in the defence against infections and cancer, and reduced levels of natural killer cell cytotoxicity have been found in people who are highly stressed: students facing important examinations, bereaved persons and those who are severely depressed.
Option (1) T-Cells — Incorrect. T cells are white blood cells that destroy invaders; the finding about reduced cytotoxicity under stress is reported for natural killer cells, not for T cells.
Option (2) B-Cells — Incorrect. B cells are the white blood cells that produce antibodies; their work is not described as cytotoxicity.
Option (4) Antibodies — Incorrect. Antibodies are not cells at all; they are produced by B cells to fight foreign bodies.
NCERT (2025-26): “Stress and the Immune System … There are several kinds of white blood cells or leucocytes within the immune system, including T cells, B cells and natural killer cells. T cells destroy invaders, and T-helper cells increase immunological activity. It is these T-helper cells that are attacked by the Human Immuno Deficiency Virus (HIV), the virus causing Acquired Immuno Deficiency Syndrome (AIDS). B cells produce antibodies. Natural killer cells are involved in the fight against both viruses and tumours. Stress can affect natural killer cell cytotoxicity, which is of major importance in the defence against various infections and cancer. Reduced levels of natural killer cell cytotoxicity have been found in people who are highly stressed, including students facing important examinations, bereaved persons, and those who are severely depressed.…” |