RECOGNITION EVENTS THAT INHIBIT AND ACTIVATE NATURAL-KILLER-CELLS

Natural killer (NK) cells exhibit specificity for MHC class I molecule s in their interactions with target cells. Instead of activating the c ells, the recognition of class I molecules on target cells inhibits NK -cell lytic activity, suggesting that surveillance of normal class I e xpression by body cells represents a key NK-cell function. Recent adva nces have been made in identification of the class I specific receptor s expressed by NK cells, and in the characterization of their detailed specificity and expression patterns. Other studies are beginning to u nravel recognition events that activate NK cells.