Killer cell, natural null cells

Null cells are also known as large granular lymphocytes , but are best known as natural killer (NK) cells. These represent a third lymphocyte subgroup. They are capable of directly lysing cancer cells and virally infected cells. 

Null cells are a separate subset of lymphocytes that lack surface markers of B or T origin. These cells, also referred to as large granular lymphocytes, are thought to perform functions such as direct cytotoxicity to foreign entities, and they act either alone (natural killer cells) or in concert with immunoglobulin (antibody-dependent cellular cytotoxicity). (Further details regarding lymphocytes are found in Chap. 84, on the immune system.)... 

Natural killer cell (NK-cell/ Null cell/LGL) ... 

Null cells Undifferentiated cells that cannot be identified as either B cells or T cells include the natural killer (NK) cells. 

Whitman, S. C., Rateri, D. L., Szilvassy, S. J., Yokoyama, W., and Daugherty, A. (2004). Depletion of natural killer cell function decreases atherosclerosis in low-density lipoprotein receptor null mice. Arterioscler Thromb. Vase. Biol. 24, 1049-1054. 

Responsible for MK (natural killer) cell activity in peripheral blood null cells... 

Natural killer (NK) cells are a subpopulation of lymphocytes that can lyse a wide variety of tumor cells and some normal cells. They are classified as null cells, being neither B or T cells. The assay usually is an in vitro one in which target cells, labeled with 51Cr are exposed to the NK cell population, and the amount of radioactive 51Cr released is measured. NK cell activity is highest in young animals (mice 5-8 weeks of age), and is present in very low levels, if at all, in older animals. However, when older rats were exposed to C. parvum or BCG, there was an increase in the cytotoxicity of the lymphocyte population. 

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