X-linked lymphoproliferative disease: the dark side of 2b4 function
A series of different receptor/ligand interactions are responsible for HLA class I-independent NK cell activation in humans. In this context, three NKspecific triggering receptors termed NKp46 (1,2), NKp44 (3,4) and NKp30 (5) have been identified, and termed Natural Cytotoxicity Receptors (NCR)(6). These receptors play a predominant role in NK cell activation in the process of natural cytotoxicity. Importantly, heterogeneity exists among different NK cells in their surface density of NCR. Thus, NCRbngntand NCRbngnt and NCRd;“ NK cells were shown to display sharp differences in the ability to kill a panel of NK susceptible target cells. In particular, the strong cytolytic activity correlates with the expression of the NCRL tphenotype whereas the expression of the NCR”’ phenotype is invariably associated with a low cytolytic activity of NK cells (7).
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