HCMV infection drives the expansion of a CD56dimCD57+NKG2C+ subset of NK cells (11, 16, 17, 45), which display a highly differentiated phenotype, including reduced responsiveness to exogenous cytokine stimulation (8, 9) and epigenetic changes at the IFNG locus (46). This evidence concerns the gene KLRC2 and cytomegalovirus infection.