Figure 3.

NK cell cytolytic activation. (A) Stages of NK cell cytolytic activity including: (i) tethering of effector to target cell and receptor binding, (ii) lytic granule and actin polarization at the immune synapse and release of lytic granules into target cells, and (iii) target cell death and release of the NK cell. NK cells can go on to serially kill or become exhausted. (B) NK cell activation relies upon a balance of activating and inhibitory signals. MHC, major histocompatibility complex.