Three distinct types of NK-cell immunologic synapses. Differences between the three types of NK-cell immunologic synapses are depicted schematically with key details noted above each. These include the cell targeted, resulting NK-cell function, synaptic accumulation of actin filaments, polarization of the MTOC and lytic granules, clustering of KIR and MHC ligands, clustering of activation receptors, and the timeframe of formation. With regard to actin accumulation, it is required by the lytic synapse in the NK cell, the regulatory synapse in the DCs, and not at all by the inhibitory synapse. See symbol key in top left corner. Professional illustration by Marie Dauenheimer.