Overall, these results support previous studies describing the HCMV-related expansion of adaptive NK cells displaying the NKG2C(+), FcRγ(–), and PLZF(–) markers in CD56dim NK cells; however, a lack of PLZF expression associated to HCMV seropositivity was also perceived in the CD56bright NK cell subset, in both controls and MS patients, in addition to an influence of HCMV-independent factors in PLZF downregulation in CD56dim NK cells found in MS cases. This evidence concerns the gene ZBTB16 and myeloid sarcoma.