Distinct integrin-dependent signals define requirements for lytic granule convergence and polarization in natural killer cells.

Lytic granules in natural killer (NK) cells represent a dangerous cargo that is targeted for secretion to destroy diseased cells. The appropriate management of these organelles enables the mounting of a precise and valuable host defense. The process of NK cell adhesion to a target cell through engagement of the integrin LFA-1 (lymphocyte function-associated antigen 1) promotes lytic granule organization through complex cellular mechanics and a signaling pathway characterized by Zhang et al. in this issue of Science Signaling. A set of signaling molecules was defined for their ability to promote the polarization of NK cell lytic granules and the microtubule organizing center (MTOC) toward the interface with a target cell. A subset of these signaling molecules was also required for the convergence of lytic granules on the MTOC.