Natural Cytotoxicity Triggering Receptor 3, NCR3, also known as NKp30, or CD337, is a natural cytotoxicity receptor. NKp30 is expressed on both resting and activated NK cells of the CD56dim, CD16+ subset that account for more that 85% of NK cells found in peripheral blood and spleen. NKp30 is absent from the CD56bright, CD16- subset that constitutes the majority of NK cells in lymph node and tonsil, however, its expression is up-regulated in these cells upon IL-2 activation .NKp30 is a member of the immunoglobulin superfamily and one of three existing natural cytotoxicity-triggering receptors. NKp30 is a glycosylated protein and is thought to be selectively expressed in resting and activated natural killer cells. NKp30 is a stimulatory receptor on human NK cells implicated in tumor immunity, and is capable of promoting or terminating dendritic cell maturation. NCR3 may play a role in inflammatory and infectious diseases.