Abstract
It has long been suspected that natural killer (NK) cells are involved in immune surveillance. Now comes new work, described by Pardoll in his Perspective, showing that gd T cells expressing an NK cell receptor called NKG2d are important for detecting precancerous skin epithelial cells in mice ( Girardi et al.). Engagement of NKG2d with its ligands Rae-1 or H60 expressed on mouse epidermal cells treated with carcinogens results in activation of gd T cells, which eliminate the precancerous epidermal cells before they become established as tumors.