Natural killer cell biology: An update and future directions Kerry S. Campbell, PhD, Jun Hasegawa, PhD  Journal of Allergy and Clinical Immunology  Volume 132, Issue 3, Pages 536-544 (September 2013) DOI: 10.1016/j.jaci.2013.07.006 Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 1 Models of NK cell education. During NK cell development, only some of the stochastically expressed inhibitory receptors (KIR in human subjects and Ly49 in mice) recognize self MHC-I ligand (SRIR). SRIR interactions promote NK cell education to mediate cytotoxicity toward an abnormal cell that has lost MHC-I expression, whereas a mature NK cell expressing only unliganded inhibitory receptors becomes hyporesponsive. Models of NK cell education are indicated as follows: (1) Rheostat, expression of more than 1 SRIR promotes more robust education; (2) Cis Interaction, interactions between SRIRs and MHC-I on the NK cell surface restrict SRIR from the immune synapse; (3) Arming, inhibitory signaling blocks chronic activation signals that would otherwise anergize (Disarming); and (4) Licensing, an ITIM-mediated signal drives education. Journal of Allergy and Clinical Immunology 2013 132, 536-544DOI: (10.1016/j.jaci.2013.07.006) Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions