Natural killer cells can discriminate between normal cells and cells that do not express
adequate amounts of major histocompatibility complex (MHC) class I molecules. The
discovery, both in mouse and in human, of MHC-specific inhibitory receptors clarified the
molecular basis of this important NK cell function. However, the triggering receptors
responsible for positive NK cell stimulation remained elusive until recently. Some of these
receptors have now been identified in humans, thus shedding some light on the molecular …