natural killer (NK) cells

nat·u·ral kill·er (NK) cells

(na'chŭr-ăl kil'ĕr selz)

Large granular lymphocytes that do not express markers of either T- or B-cell lineage. These cells kill target cells using antibody-dependent cell-mediated cytotoxicity. NK cells can also use perforin to kill cells in the absence of antibody. Killing may occur without previous sensitization.
Synonym(s): NK cells.