Figure 1.

NK cell receptors, their function, and ligands. Schematic illustration showing how NK cell activity and cytotoxicity are controlled by signals from cell surface receptors. Cytokines and corresponding cytokine receptors on the NK cell are shown at the lower part of the NK cell. Inhibitory signals triggered by receptors (red) upon engagement of their ligands (in brackets) are shown on the left side of the NK cell. Activating signals triggered by receptors (green) upon engagement of their ligands (in brackets) are shown on the right side. Binding of LFA-1 (blue) on NK cells to ICAM-1 on target cells direct the granulae release toward the target cell, which is needed for efficient target cell lysis.