B3GAT1 and infection: At contrast with the NKG2A−KIR+CD57+ fully mature PD-1pos NK cell population recently described in CMV-seropositive healthy controls [40], we found a similar proportion of PD-1pos and PD-1neg NK cells expressing CD57, a marker of CD56dim late differentiation suggested to mark memory-like NK cells that have been expanded in response to infection [48].