KLRB1 and cytomegalovirus infection: This was also specific to the NKG2C+ subset of NK cells since no statistically significant differences in the frequencies of granzyme B+ cells in NKR‐P1A+ and NKR‐P1A‒ subsets of NKG2C‒ NK cells were observed in HSCT patients with active CMV infection (Figure 2H).