Natural killer (NK) cells are lymphocytes that can mediate the lysis of certain tumor cells and virus infected cells without being previously activated. They can also regulate specific humoral and cell mediated immunity. NK cells preferentially express several calcium dependent (C type) lectins, which have been implicated in the regulation of NK cell function. The group, designated KLRC (NKG2) are expressed primarily in natural killer (NK) cells and encodes a family of transmembrane proteins