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natural killer cellsZoomA-Z

Subject - Immunology

Natural killer cells (NK cells) are cells of the immune system that are able to kill other cells without first being sensitized. They are thus considered to be part of the innate immunological defence. The attribute of "natural" is used to differentiate them from other killer cells of the immune system, which require an antibody-induced specific activation, like the cytotoxic T lymphocytes. Natural killer cells make up about 10-15% of all lymphocytes in blood. They can recognize changes in the surface structure of the body’s cells, like those that occur with viral infections and neoplastic changes that precede tumor formation. Their function is to recognize and eliminate such altered cells. The activity of natural killer cells is partially regulated by receptors that recognize molecules of the major histocompatibility complex (MHC).